Abstract:
The invention relates to compounds of the formula 1  
                         
 
     and to pharmaceutically acceptable salts, solvates and prodrugs thereof, wherein R, R 1 , R 2 , R 3 , R 4 , R 5 , R 6  and R 7  are as defined herein. The invention also relates to pharmaceutical compositions containing the compounds of formula 1, methods of treating infections by administering the compounds of formula 1, and methods of preparing the compounds of formula 1.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to novel tricyclic erythromycin derivatives. The compounds of this invention are useful as antibiotic agents in mammals, including man, as well as in fish and birds. The compounds of the present invention are broad-spectrum macrolide antibiotics that are effective against infections caused by certain gram-positive and gram-negative bacteria as well as protozoa. Various derivatives of erythromycin A that are useful as antibiotic agents are referred to in U.S. patent application Ser. No. 60/049,349, filed Jun. 11, 1997; U.S. application Ser. No. 60/046,150, filed May 9, 1997; U.S. patent application Ser. No. 60/063,676, filed Oct. 29, 1997; U.S. patent application Ser. No. 60/087,798, filed Jun. 3, 1998; U.S. application Ser. No. 60/054,866, filed Aug. 6, 1997; and U.S. patent application Ser. No. 60/063,161, filed Oct. 29, 1997; each of the foregoing U.S. patent applications is incorporated herein by reference in its entirety.  
         SUMMARY OF THE INVENTION  
         [0002]    The present invention relates to compounds of the formula 1  
                         
 
           [0003]    and to pharmaceutically acceptable salts, solvates and prodrugs thereof, wherein:  
           [0004]    R is C 1 -C 10  alkyl, C 3 -C 10  alkenyl, or C 3 -C 10  alkynyl, wherein one or two carbons of said alkyl, alkenyl, and alkynyl groups are optionally replaced by a heteroatom selected from O, S and —N(R 12 )—, and are optionally substituted by 1 to 5 R 13  substituents, with the proviso that R is not ethyl when R 7  is H;  
           [0005]    each R 1 , R 2 , R 3 , and R 4  is independently selected from H, C 1 -C 12  alkyl, C 3 -C 10  alkenyl, C 3 -C 10  alkynyl, —(CR 8 R 9 ) m Z, wherein m is an integer from 0 to 6, one or two carbons of said alkyl, alkenyl, and alkynyl groups are optionally replaced by a heteroatom independently selected from O, S and —N(R 12 )—, and the foregoing groups, except H, are optionally substituted by 1 to 5 R 13  substituents;  
           [0006]    R 2  and R 3  together with the carbon to which they are attached form a 3 to 10 membered carbocyclic ring in which one or two carbons are optionally replaced by a heteroatom selected from O, S and —N(R 12 )—;  
           [0007]    R 5  is selected from C 1 -C 10  alkyl, C 3 -C 10  alkenyl, C 3 -C 10  alkynyl, —CH 2 —CH═CH—Z, or —(CR 9 R 10 ) n Z, wherein n is an integer from 1 to 6; and the foregoing R 5  groups are optionally substituted by 1 to 5 R 13  substituents;  
           [0008]    R 6  is H, —C(O)O(C 1 -C 18  alkyl) or —C(O)(C 1 -C 18  alkyl), wherein one or two carbon atoms of the alkyl moieties of the foregoing groups are optionally replaced by a heteroatom selected from O, S and —N(R 12 )—;  
           [0009]    R 7 is H, C 1 -C 6  alkyl, —OR 10 , —NR 10 R 11 , or halo;  
           [0010]    each R 8  and R 9  is independently selected from H, halo, and C 1 -C 6  alkyl;  
           [0011]    or R 8  and R 9  together with the carbon to which they are attached form a 3 to 10 membered carbocyclic or 4 to 10 membered heterocyclic ring;  
           [0012]    each R 10  and R 11  is H, C 1 -C 12  alkyl, —(C 1 -C 12  alkyl)(C 6 -C 10  aryl), C 6 -C 10  aryl, or —(C 1 -C 12  alkyl)(4 to 10 membered heterocyclic), wherein one or two carbons of the alkyl moieties of the foregoing groups are optionally replaced by a heteroatom selected from O, S and —N(R 12 )—;  
           [0013]    each R 12  is independently H or C 1 -C 6  alkyl optionally substituted by 1 to 3 fluoro moieties;  
           [0014]    each R 13  is independently selected from the group consisting of halo, trifluoromethyl, difluoromethoxy, trifluoromethoxy, nitro, N 3 , cyano, —OR 10 , C 1 -C 10  alkyl, C 2 -C 10  alkenyl, C 2 -C 10  alkynyl, C 6 -C 10  aryl, 4 to 10 membered heterocyclic, —(C 1 -C 10  alkyl)(C 6 -C 10  aryl), —(C 1 -C 10  alkyl)(4 to 10 membered heterocyclic), —C(O)R 10 , —C(O)OR 10 , —NR 10 R 11 , —NHC(O)OR 10 , —OC(O)R 10 , —NHSO 2 R 10 , —C(O)NR 10 R 11 , —NHC(O)R 10 , —NHC(O)NR 10 R 11 , —SO 2 NR 10 R 11 , —S(O) j (CH 2 ) m (C 6 -C 10  aryl), and —S(O) j (C 1 -C 6  alkyl), wherein j is an integer from 0 to 2 and m is integer from 0 to 4;  
           [0015]    each Z is independently a 4 to 10 membered heterocyclic group or C 6 -C 10  aryl, wherein said heterocyclic and aryl groups are optionally substituted by 1 to 5 R 13  substituents.  
           [0016]    More specific embodiments of this invention include compounds of formula 1 wherein R 5  is methyl, ethyl, n-propyl, or —CH 2 —CH═CH—Z.  
           [0017]    More specific embodiments of this invention include compounds of formula 1 wherein R is methyl, ethyl, n-propyl, cyclopropyl, cyclobutyl, or cyclopentyl.  
           [0018]    More specific embodiments of this invention include compounds of formula 1 wherein R 7  is OH, F, Cl, or Br.  
           [0019]    More specific embodiments of this invention include compounds of formula 1 wherein R 6  is H.  
           [0020]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each independently H, methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl or cyclopropyl.  
           [0021]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each H.  
           [0022]    More specific embodiments of this invention include compounds of formula 1 wherein R 1 , R 2 , R 3  and R 4  are each independently —(CH 2 ) m Z, m is an integer ranging from 0 to 6 and Z is as defined for the compound of formula 1.  
           [0023]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each H, R 1  is —(CH 2 ) m Z, m is an integer ranging from 0 to 6 and Z is as defined for the compound of formula 1.  
           [0024]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R 1  is —(CH 2 ) m Z, m is an integer ranging from 0 to 6 and Z is as defined for the compound of formula 1.  
           [0025]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R is ethyl or methyl, R 1  is —(CH 2 ) m Z, m is an integer ranging from 0 to 6 and Z is as defined for the compound of formula 1.  
           [0026]    More specific embodiments of this invention include compounds of formula 1 wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R 7  is F, R is ethyl or methyl, R 1  is —(CH 2 ) m Z, m is an integer ranging from 0 to 6 and Z is as defined for the compound of formula 1.  
           [0027]    More specific embodiments of the compounds of formula 1 include those wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R 7  is F, R is ethyl or methyl, R 1  is —(CH 2 ) m Z, m is an integer from 0 to 6, and Z is selected from quinolin-4-yl, 4-phenyl-1-imidazol-1-yl, imidazo(4,5-b)pyridin-3-yl, and 4-pyridin-3-yl-imidazol-1-yl.  
           [0028]    More specific embodiments of the compounds of formula 1 include those wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R 7  is F, R is ethyl or methyl, R 1  is —(CH 2 ) 3 Z, Z is as defined for the compound of formula 1.  
           [0029]    More specific embodiments of the compounds of formula 1 include those wherein R 2 , R 3  and R 4  are each H, R 5  is methyl, R 7  is F, R is ethyl or methyl, R 1  is —(CH 2 ) 3 Z, and Z is quinolin-4-yl, 4-phenyl-1-imidazol-1-yl, imidazo(4,5-b)pyridin-3-yl, or 4-pyridin-3-yl-imidazol-1-yl.  
           [0030]    Examples of preferred compounds of this invention include the compounds of formula 1 selected from the group consisting of:  
           [0031]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-quinolin-4-yl-propyl;  
           [0032]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-quinolin-5-yl-propyl;  
           [0033]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H. R 5  is methyl, R 7  is F, and R 1  is 3-quinolin-8-yl-propyl;  
           [0034]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H. R 5  is methyl, R 7  is F, and R 1  is 3-(7-methoxy-quinolin-4-yl)-propyl;  
           [0035]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-(4-phenyl-imidazol-1-yl)-propyl;  
           [0036]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-pyridin-4-yl-propyl;  
           [0037]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-pyridin-3-yl-propyl;  
           [0038]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 5  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-pyridin-2-yl-propyl;  
           [0039]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-(4-pyridin-3-yl-imidazol-1-yl)-propyl or 3-phenyl-propyl;  
           [0040]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-(3-fluoro)-phenyl-propyl;  
           [0041]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 5  are each H, R 5  is methyl, R 7  is F, and R 1  is 3-(imidazo(4,5-b)pyridin-3-yl)-propyl or 3-(2-phenyl-thiazol-5-yl)-propyl;  
           [0042]    the compound of formula 1 wherein R is methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 5  is methyl, R 7  is F, R 1  is 3-(2-pyridin-3-yl-thiazol-4-yl)-propyl or 3-benzoimidazol-1-yl-propyl;  
           [0043]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH═CH 2 —(4-pyridyl) or —CH 2 CH 2 CH 2 —(4-pyridyl);  
           [0044]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH 2 CH 2 —(4-quinolinyl);  
           [0045]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH═CH—(4-quinolinyl);  
           [0046]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH 2 CH 2 —(5-quinolinyl);  
           [0047]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH═CH—(5-quinolinyl);  
           [0048]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH 2 CH 2 —(4-benzimidazolyl);  
           [0049]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH═CH—(4-benzimidazolyl) or —CH 2 CH 2 CH 2 —(8-quinolinyl);  
           [0050]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH═CH—(8-quinolinyl) or —CH 2 CH 2 NHCH 2 —(4-pyridyl);  
           [0051]    the compound of formula 1 wherein R 1  is H, methyl or ethyl; R 2 , R 3 , R 4  and R 6  are each H, R 7  is F, and R 5  is —CH 2 CH 2 NHCH 2 —(4-quinolinyl);  
           [0052]    the pharmaceutically acceptable salts, solvates and prodrugs of the foregoing compounds.  
           [0053]    The invention also relates to a pharmaceutical composition for the treatment of a bacterial infection or protozoa infection in a mammal, fish, or bird which comprises a therapeutically effective amount of a compound of formula 1, or a pharmaceutically acceptable salt, solvate or prodrug thereof, and a pharmaceutically acceptable carrier.  
           [0054]    The invention also relates to a method of treating a bacterial infection or a protozoa infection in a mammal, fish, or bird which comprises administering to said mammal, fish or bird a therapeutically effective amount of a compound of formula 1 or a pharmaceutically acceptable salt, solvate or prodrug thereof.  
           [0055]    The present invention also relates to a method of preparing a compound of formula 1, as described above, which comprises treating a compound of the formula 2  
                         
 
           [0056]    wherein R, R 1 , R 2 , R 3 , R 4  and R 5  are as defined above for the compound of formula 1, P is a protecting group for a hydroxyl group as described in T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 2 nd  Ed., John Wiley &amp; Sons, Inc., pp10-142, with a base followed by a halogenating agent or an appropriate electrophile that includes the R 7  moiety. Examples of suitable bases include sodium hydride, potassium hydride, sodium or potassium, DBU (1,8-diazabicyclo[5,4,0]undec-7-ene), lithium or sodium or potassium diisopropylamide, and potassium or sodium hydroxide. Examples of suitable halogenating agents include (ArSO 2 ) 2 N-halogen, wherein Ar is C 6 -C 10  aryl, and (1-(chloromethyl)4-fluoro-1,4-diazonibicyclo(2.2.2)octane bis(tetrafluoroborate)). The preparation of the compound of formula 2, wherein R is ethyl, R 5  is methyl, is described in PCT international patent application number PCT/IB98/01559 (filed Oct. 8, 1998), and the preparation of the compound of formula 2 wherein R is not ethyl and R 5  is a methyl group is described in U.S. provisional patent application No. 60/070358 (filed Jan. 2, 1998).  
           [0057]    The present invention also relates to a method of preparing a compound of formula 1, as described above, which comprises treating a compound of formula 3  
                         
 
           [0058]    with a compound of the formula R 2 R 3 C(═O), wherein R 2  and R 3  are as defined above, in the presence of an acid in a solvent. The preferred acids are formic acid, acetic acid, and p-toluenesulfonic acid, and the preferred solvents are THF (tetrahydrofuran), dichloromethane, chloroform, and mixtures of two or more of the foregoing solvents. The preparation of the compound of formula 3 is described in PCT international patent application number PCT/IB98/01578 (filed Oct. 9, 1998).  
           [0059]    As used herein, unless otherwise indicated, the term “infection” refers to “bacterial infection(s)” and “protozoa infection(s)”; including bacterial infections and protozoa infections that occur in mammals, fish and birds as well as disorders related to bacterial infections and protozoa infections that may be treated or prevented by administering antibiotics such as the compounds of the present invention. Such bacterial infections and protozoa infections and disorders related to such infections include the following: pneumonia, otitis media, sinusitus, bronchitis, tonsillitis, and mastoiditis related to infection by  Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus,  or Peptostreptococcus spp.; pharynigitis, rheumatic fever, and glomerulonephritis related to infection by  Streptococcus pyogenes,  Groups C and G streptococci,  Clostridium diptheriae,  or  Actinobacillus haemolyticum;  respiratory tract infections related to infection by  Mycoplasma pneumoniae, Legionella pneumophila, Streptococcus pneumoniae, Haemophilus influenzae,  or  Chlamydia pneumoniae;  uncomplicated skin and soft tissue infections, abscesses and osteomyelitis, and puerperal fever related to infection by  Staphylococcus aureus,  coagulase-positive staphylococci (i.e.,  S. epidermidis, S. hemolyticus,  etc.),  Streptococcus pyogenes, Streptococcus agalactiae,  Streptococcal groups C-F (minute-colony streptococci), viridans streptococci,  Corynebacterium minutissimum,  Clostridium spp., or  Bartonella henselae;  uncomplicated acute urinary tract infections related to infection by  Staphylococcus saprophyticus  or Enterococcus spp.; urethritis and cervicitis; and sexually transmitted diseases related to infection by  Chlamydia trachomatis, Haemophilus ducreyi, Treponema pallidum, Ureaplasma urealyticum,  or  Neiserria gonorrheae;  toxin diseases related to infection by  S. aureus  (food poisoning and Toxic shock syndrome), or Groups A, B, and C streptococci; ulcers related to infection by  Helicobacter pylori;  systemic febrile syndromes related to infection by  Borrelia recurrentis;  Lyme disease related to infection by  Borrelia burgdorferi;  conjunctivitis, keratitis, and dacrocystitis related to infection by  Chlamydia trachomatis, Neisseria gonorrhoeae, S. aureus, S. pneumoniae, S. pyogenes, H. influenzae,  or Listeria spp.; disseminated  Mycobacterium avium  complex (MAC) disease related to infection by  Mycobacterium avium,  or  Mycobacterium intracellulare;  gastroenteritis related to infection by  Campylobacter jejuni;  intestinal protozoa related to infection by Cryptosporidium spp.; odontogenic infection related to infection by viridans streptococci; persistent cough related to infection by  Bordetella pertussis;  gas gangrene related to infection by  Clostridium perfringens  or Bacteroides spp.; and atherosclerosis related to infection by  Helicobacter pylori  or  Chlamydia pneumoniae.  Bacterial infections and protozoa infections and disorders related to such infections that may be treated or prevented in animals include the following: bovine respiratory disease related to infection by  P. haem., P. multocida, Mycoplasma bovis,  or Bordetella spp.; cow enteric disease related to infection by  E. coli  or protozoa (i.e., coccidia, cryptosporidia, etc.); dairy cow mastitis related to infection by  Staph. aureus, Strep. uberis, Strep. agalactiae, Strep. dysgalactiae,  Klebsiella spp., Corynebacterium, or Enterococcus spp.; swine respiratory disease related to infection by  A. pleuro., P. multocida,  or Mycoplasma spp.; swine enteric disease related to infection by  E. coli, Lawsonia intracellularis,  Salmonella, or  Serpulina hyodyisinteriae;  cow footrot related to infection by Fusobacterium spp.; cow metritis related to infection by  E. coli;  cow hairy warts related to infection by  Fusobacterium necrophorum  or  Bacteroides nodosus;  cow pink-eye related to infection by  Moraxella bovis;  cow premature abortion related to infection by protozoa (i.e. neosporium); urinary tract infection in dogs and cats related to infection by  E. coli;  skin and soft tissue infections in dogs and cats related to infection by  Staph. epidermidis, Staph. intermedius,  coagulase neg. Staph. or  P. multocida;  and dental or mouth infections in dogs and cats related to infection by Alcaligenes spp., Bacteroides spp., Clostridium spp., Enterobacter spp., Eubacterium, Peptostreptococcus, Porphyromonas, or Prevotella. Other bacterial infections and protozoa infections and disorders related to such infections that may be treated or prevented in accord with the method of the present invention are referred to in J. P. Sanford et al., “The Sanford Guide To Antimicrobial Therapy,” 26 th  Edition, (Antimicrobial Therapy, Inc., 1996).  
           [0060]    The term “treatment”, as used herein, unless otherwise indicated, includes the treatment or prevention of a bacterial infection or protozoa infection as provided in the method of the present invention.  
           [0061]    The term “halo”, as used herein, unless otherwise indicated, means fluoro, chloro, bromo or iodo. Preferred halo groups are fluoro, chloro and bromo.  
           [0062]    The term “alkyl”, as used herein, unless otherwise indicated, includes saturated monovalent hydrocarbon radicals having straight, cyclic or branched moieties, or a combination of the foregoing moieties. Said alkyl group may include one or two double or triple bonds. It is understood that for cyclic moieties at least three carbon atoms are required in said alkyl group.  
           [0063]    The term “alkanoyl”, as used herein, unless otherwise indicated, includes —C(O)—alkyl groups wherein “alkyl” is as defined above.  
           [0064]    The term “aryl”, as used herein, unless otherwise indicated, includes an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, such as phenyl or naphthyl.  
           [0065]    As used herein, unless otherwise indicated, “Ac” indicates an acetyl group.  
           [0066]    As used herein, unless otherwise indicated, “Me” indicates a methyl group.  
           [0067]    As used herein, unless otherwise indicated, “Et” indicates an ethyl group.  
           [0068]    The term “4 to 10 membered heterocyclic”, as used herein, unless otherwise indicated, includes aromatic and non-aromatic heterocyclic groups containing one or more heteroatoms each selected from O, S and N, wherein each heterocyclic group has from 4-10 atoms in its ring system. Non-aromatic heterocyclic groups include groups having only 4 atoms in their ring system, but aromatic heterocyclic groups must have at least 5 atoms in their ring system. The heterocyclic groups include benzo-fused ring systems and ring systems substituted with one or more oxo moieties. An example of a 4 membered heterocyclic group is azetidinyl (derived from azetidine). An example of a 5 membered heterocyclic group is thiazolyl and an example of a 10 membered heterocyclic group is quinolinyl. Examples of non-aromatic heterocyclic groups are pyrrolidinyl, tetrahydrofuranyl, tetrahydrothienyl, tetrahydropyranyl, tetrahydrothiopyranyl, piperidino, morpholino, thiomorpholino, thioxanyl, piperazinyl, azetidinyl, oxetanyl, thietanyl, homopiperidinyl, oxepanyl, thiepanyl, oxazepinyl, diazepinyl, thiazepinyl, 1,2,3,6-tetrahydropyridinyl, 2-pyrrolinyl, 3-pyrrolinyl, indolinyl, 2H-pyranyl, 4H-pyranyl, dioxanyl, 1,3-dioxolanyl, pyrazolinyl, dithianyl, dithiolanyl, dihydropyranyl, dihydrothienyl, dihydrofuranyl, pyrazolidinyl, imidazolinyl, imidazolidinyl, 3-azabicyclo[3.1.0]hexanyl, 3-azabicyclo[4.1.0]heptanyl, 3H-indolyl and quinolizinyl. Examples of aromatic heterocyclic groups are pyridinyl, imidazolyl, pyrimidinyl, pyrazolyl, triazolyl, pyrazinyl, tetrazolyl, furyl, thienyl, isoxazolyl, thiazolyl, oxazolyl, isothiazolyl, pyrrolyl, quinolinyl, isoquinolinyl, indolyl, benzimidazolyl, benzofuranyl, cinnolinyl, indazolyl, indolizinyl, phthalazinyl, pyridazinyl, triazinyl, isoindolyl, pteridinyl, purinyl, oxadiazolyl, thiadiazolyl, furazanyl, benzofurazanyl, benzothiophenyl, benzothiazolyl, benzoxazolyl, quinazolinyl, quinoxalinyl, naphthyridinyl, and furopyridinyl. The foregoing groups, as derived from the compounds listed above, may be C-attached or N-attached where such is possible. For instance, a group derived from pyrrole may be pyrrol-1-yl (N-attached) or pyrrol-3-yl (C-attached).  
           [0069]    The phrase “pharmaceutically acceptable salt(s)”, as used herein, unless otherwise indicated, includes salts of acidic or basic groups which may be present in the compounds of the present invention. The compounds of the present invention that are basic in nature are capable of forming a wide variety of salts with various inorganic and organic acids. The acids that may be used to prepare pharmaceutically acceptable acid addition salts of such basic compounds of are those that form non-toxic acid addition salts, i.e., salts containing pharmacologically acceptable anions, such as the hydrochloride, hydrobromide, hydroiodide, nitrate, sulfate, bisulfate, phosphate, acid phosphate, isonicotinate, acetate, lactate, salicylate, citrate, acid citrate, tartrate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucuronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate and pamoate [1,1′-methylene-bis-(2-hydroxy-3-naphthoate)] salts. The compounds of the present invention that include a basic moiety, such as an amino group, may form pharmaceutically acceptable salts with various amino acids, in addition to the acids mentioned above.  
           [0070]    Those compounds of the present invention that are acidic in nature are capable of forming base salts with various pharmacologically acceptable cations. Examples of such salts include the alkali metal or alkaline earth metal salts and, particularly, the calcium, magnesium, sodium and potassium salts of the compounds of the present invention.  
           [0071]    In the chemical structures depicted herein, a wavy line indicates that the stereochemistry at the chiral center to which the wavy line is connected is either an R or S configuration where the wavy line is connected to a carbon atom.  
           [0072]    The compounds of the present invention have asymmetric centers and therefore exist in different enantiomeric and diastereomeric forms. This invention relates to the use of all optical isomers and stereoisomers of the compounds of the present invention, and mixtures thereof, and to all pharmaceutical compositions and methods of treatment that may employ or contain them. In particular, the invention includes both the R and S configurations of C-2 of the macrolide ring of formula 1. The compounds of formula 1 may also exist as tautomers. This invention relates to the use of all such tautomers and mixtures thereof.  
           [0073]    The subject invention also includes isotopically-labelled compounds, and the pharmaceutically acceptable salts thereof, which are identical to those recited in formula 1, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into compounds of the invention include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, fluorine and chlorine, such as  2 H,  3 H,  13 C,  14 C,  15 N,  18 O,  17 O,  35 S,  18 F, and  36 Cl, respectively. Compounds of the present invention, prodrugs thereof, and pharmaceutically acceptable salts of said compounds or of said prodrugs which contain the aforementioned isotopes and/or other isotopes of other atoms are within the scope of this invention. Certain isotopically-labelled compounds of the present invention, for example those into which radioactive isotopes such as  3 H and  14 C are incorporated, are useful in drug and/or substrate tissue distribution assays. Tritiated, i.e.,  3 H, and carbon-14, i.e.,  14 C, isotopes are particularly preferred for their ease of preparation and detectability. Further, substitution with heavier isotopes such as deuterium, i.e.,  2 H, can afford certain therapeutic advantages resulting from greater metabolic stability, for example increased in vivo half-life or reduced dosage requirements and, hence, may be preferred in some circumstances. Isotopically labelled compounds of formula 1 of this invention and prodrugs thereof can generally be prepared by carrying out the procedures disclosed in the Schemes and/or in the Examples and Preparations below, by substituting a readily available isotopically labelled reagent for a non-isotopically labelled reagent.  
           [0074]    This invention also encompasses pharmaceutical compositions containing and methods of treating bacterial infections through administering prodrugs of compounds of the formula 1. Compounds of formula 1 having free amino, amido, hydroxy or carboxylic groups can be converted into prodrugs. Prodrugs include compounds wherein an amino acid residue, or a polypeptide chain of two or more (e.g., two, three or four) amino acid residues is covalently joined through an amide or ester bond to a free amino, hydroxy or carboxylic acid group of compounds of formula 1. The amino acid residues include but are not limited to the 20 naturally occurring amino acids commonly designated by three letter symbols and also includes 4-hydroxyproline, hydroxylysine, demosine, isodemosine, 3-methylhistidine, norvalin, beta-alanine, gamma-aminobutyric acid, citrulline homocysteine, homoserine, ornithine and methionine sulfone.  
           [0075]    Additional types of prodrugs are also encompassed. For instance, free carboxyl groups can be derivatized as amides or alkyl esters. The amide and ester moieties may incorporate groups including but not limited to ether, amine and carboxylic acid functionalities. Free hydroxy groups may be derivatized using groups including but not limited to hemisuccinates, phosphate esters, dimethylaminoacetates, and phosphoryloxymethyloxycarbonyls, as outlined in D. Fleisher, R. Bong, B. H. Stewart, Advanced Drug Delivery Reviews (1996) 19, 115. Carbamate prodrugs of hydroxy and amino groups are also included, as are carbonate prodrugs and sulfate esters of hydroxy groups. Derivatization of hydroxy groups as (acyloxy)methyl and (acyloxy)ethyl ethers wherein the acyl group may be an alkyl ester, optionally substituted with groups including but not limited to ether, amine and carboxylic acid functionalities, or where the acyl group is an amino acid ester as described above, are also encompassed. Prodrugs of this type are described in R. P. Robinson et al., J. Medicinal Chemistry (1996) 39, 10.  
         DETAILED DESCRIPTION OF THE INVENTION  
         [0076]    The preparation of the compounds of the present invention is illustrated in the following Schemes 1 to 2.  
                         
 
           [0077]    Scheme 1 illustrates the general synthesis of compounds of formula 1 where in R 6  is hydrogen. The starting compound of formula 4 wherein R 5  is methyl group can be made following the procedures described in PCT international patent application number PCT/IB98/01559, filed Oct. 8, 1998, and in U.S. provisional patent application No. 60/070358, filed Jan. 2, 1998. The preparation of the compound of formula 4 wherein R 5  is a group other than a methyl group, in accord with the definition of R 5  provided above with respect to the compound of formula 1, can be accomplished by following substantially the same procedures described in PCT international patent application number PCT/IB98/01559, referred to above. The C-2′ hydroxyl group of the compound of formula 4 may be protected as shown in step  1  of Scheme 1 by using the methods described in T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 2 nd  Ed., John Wiley &amp; Sons, Inc., pp. 10-142, referred to above. The preferred protecting groups are silyl ethers, for example, trimethylsilyl ether, or esters, for example, acetate, benzoate. The compound of formula 2 can be converted to the compound of formula 5 (step  2  of Scheme 1) by treating the compound of formula 2 with a base followed by treatment with a halogenating agent or an appropriate electrophile containing an appropriate R 7  moiety. Examples of suitable bases include sodium hydride, potassium hydride, sodium or potassium, DBU (1,8-diazabicyclo[5,4,0]undec-7-ene), lithium or sodium or potassium diisopropylamide, and potassium or sodium hydroxide. An example of a suitable halogenating agent is (ArSO 2 ) 2 N-halogen, wherein Ar is C 6 -C 10  aryl.  
           [0078]    Step  3  of Scheme 1 describes the removal of the C-2′ protecting group which may be done by a variety of methods as summarized in T. W. Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 2 nd  Ed., John Wiley &amp; Sons, Inc., pp. 10-142, referred to above.  
                         
 
           [0079]    Scheme 2 outlines another method for the general synthesis of compounds of formula 6 which correspond to compounds of formula 1 wherein R 6  is hydrogen. The preparation of compound  3  has been described in PCT international patent application number PCT/IB98/01578, filed Oct. 9, 1998. Treatment of the compound of formula 3 with a compound of formula R 2 R 3 C(═O), wherein R 2  and R 3  are as defined above, in the presence of an acid in a solvent yields the compound of formula 6. The preferred acids are formic acid, acetic acid, p-toluenesulfonic acid and the preferred solvents are THF (tetrahydrofuran), dichloromethane, and chloroform, and mixtures of two or more of the foregoing solvents.  
           [0080]    The compounds of the present invention may have asymmetric carbon atoms. Such diasteromeric mixtures can be separated into their individual diastereomers on the basis of their physical chemical differences by methods known to those skilled in the art, for example, by chromatography or fractional crystallization. Enantiomers can be separated by converting the enantiomeric mixtures into a diastereomric mixture by reaction with an appropriate optically active compound (e.g., alcohol), separating the diastereomers and converting (e.g., hydrolyzing) the individual diastereomers to the corresponding pure enantiomers. All such isomers, including diastereomer mixtures and pure enantiomers are considered as part of the invention.  
           [0081]    The compounds of formula 1 that are basic in nature are capable of forming a wide variety of different salts with various inorganic and organic acids. Although such salts must be pharmaceutically acceptable for administration to animals, it is often desirable in practice to initially isolate the compound of formula 1 from the reaction mixture as a pharmaceutically unacceptable salt and then simply convert the latter back to the free base compound by treatment with an alkaline reagent and subsequently convert the latter free base to a pharmaceutically acceptable acid addition salt. The acid addition salts of the base compounds of this invention are readily prepared by treating the base compound with a substantially equivalent amount of the chosen mineral or organic acid in an aqueous solvent medium or in a suitable organic solvent, such as methanol or ethanol. Upon careful evaporation of the solvent, the desired solid salt is readily obtained. The desired acid salt can also be precipitated from a solution of the free base in an organic solvent by adding to the solution an appropriate mineral or organic acid.  
           [0082]    Those compounds of formula 1 that are acidic in nature are capable of forming base salts with various pharmacologically acceptable cations. Examples of such salts include the alkali metal or alkaline-earth metal salts and particularly, the sodium and potassium salts. These salts may be prepared by conventional techniques. The chemical bases which are used as reagents to prepare the pharmaceutically acceptable base salts of this invention are those which form non-toxic base salts with the acidic compounds of formula 1. Such non-toxic base salts include those derived from such pharmacologically acceptable cations as sodium, potassium calcium and magnesium, etc. These salts can be prepared by treating the corresponding acidic compounds with an aqueous solution containing the desired pharmacologically acceptable cations, and then evaporating the resulting solution to dryness, preferably under reduced pressure. Alternatively, they may also be prepared by mixing lower alkanolic solutions of the acidic compounds and the desired alkali metal alkoxide together, and then evaporating the resulting solution to dryness in the same manner as before. In either case, stoichiometric quantities of reagents are preferably employed in order to ensure completeness of reaction and maximum yields of the desired final product.  
           [0083]    The activity of the compounds of the present invention against bacterial and protozoa pathogens is demonstrated by the compound′s ability to inhibit growth of defined strains of human (Assay I) or animal (Assays II and III) pathogens.  
           [0084]    Assay I  
           [0085]    Assay I, described below, employs conventional methodology and interpretation criteria and is designed to provide direction for chemical modifications that may lead to compounds that circumvent defined mechanisms of macrolide resistance. In Assay I, a panel of bacterial strains is assembled to include a variety of target pathogenic species, including representatives of macrolide resistance mechanisms that have been characterized. Use of this panel enables the chemical structure/activity relationship to be determined with respect to potency, spectrum of activity, and structural elements or modifications that may be necessary to obviate resistance mechanisms. Bacterial pathogens that comprise the screening panel are shown in the table below. In many cases, both the macrolide-susceptible parent strain and the macrolide-resistant strain derived from it are available to provide a more accurate assessment of the compound&#39;s ability to circumvent the resistance mechanism. Strains that contain the gene with the designation of ermA/ermB/ermC are resistant to macrolides, lincosamides, and streptogramin B antibiotics due to modifications (methylation) of 23S rRNA molecules by an Erm methylase, thereby generally prevent the binding of all three structural classes. Two types of macrolide efflux have been described; msrA encodes a component of an efflux system in staphylococci that prevents the entry of macrolides and streptogramins while mefA/E encodes a transmembrane protein that appears to efflux only macrolides. Inactivation of macrolide antibiotics can occur and can be mediated by either a phosphorylation of the 2′-hydroxyl (mph) or by cleavage of the macrocyclic lactone (esterase). The strains may be characterized using conventional polymerase chain reaction (PCR) technology and/or by sequencing the resistance determinant. The use of PCR technology in this application is described in J. Sutcliffe et al., “Detection Of Erythromycin-Resistant Determinants By PCR”, Antimicrobial Agents and Chemotherapy, 40(11), 2562-2566 (1996). The antibacterial assay is performed in microtiter trays and interpreted according to  Performance Standards for Antimicrobial Disk Susceptibility Tests - Sixth Edition; Approved Standard,  published by The National Committee for Clinical Laboratory Standards (NCCLS) guidelines; the minimum inhibitory concentration (MIC) is used to compare strains. acr AB or acr AB-like indicates that an intrinsia multidrug efflux pump exists in the strain. Compounds are initially dissolved in dimethylsulfoxide (DMSO) as 40 mg/ml stock solutions.  
                                   Strain Designation   Macrolide Resistance Mechanism(s)                     Staphylococcus aureus  1116   susceptible parent         Staphylococcus aureus  1117   ermB         Staphylococcus aureus  0052   susceptible parent         Staphylococcus aureus  1120   ermC         Staphylococcus aureus  1032   msrA, mph, esterase         Staphylococcus hemolyticus  1006   msrA, mph         Streptococcus pyogenes  0203   susceptible parent         Streptococcus pyogenes  1079   ermB         Streptococcus pyogenes  1062   susceptible parent         Streptococcus pyogenes  1061   ermB         Streptococcus pyogenes  1064   mefA         Streptococcus agalactiae  1024   susceptible parent         Streptococcus agalactiae  1023   ermB         Streptococcus pneumoniae  1016   susceptible         Streptococcus pneumoniae  1046   ermB         Streptococcus pneumoniae  1095   ermB         Streptococcus pneumoniae  1175   mefE         Haemophilus influenzae  0085   susceptible; acr AB-like         Haemophilus influenzae  0131   susceptible; acr AB-like         Moraxella catarrhalis  0040   susceptible         Moraxella catarrhalis  1055   erythromycin intermediate resistance         Escherichia coli  0266   susceptible; acr AB         Haemophilus influenzae  1100   susceptible; acr AB-like                  
 
           [0086]    Assay II is utilized to test for activity against  Pasteurella multocida  and Assay III is utilized to test for activity against  Pasteurella haemolytica.    
           [0087]    Assay II  
           [0088]    This assay is based on the liquid dilution method in microliter format. A single colony of  P. multocida  (strain 59A067) is inoculated into 5 ml of brain heart infusion (BHI) broth. The test compounds are prepared by solubilizing 1 mg of the compound in 125 μl of dimethylsulfoxide (DMSO). Dilutions of the test compound are prepared using uninoculated BHI broth. The concentrations of the test compound used range from 200 μg/ml to 0.098 μg/ml by two-fold serial dilutions. The  P. multocida  inoculated BHI is diluted with uninoculated BHI broth to make a 10 4  cell suspension per 200 μl. The BHI cell suspensions are mixed with respective serial dilutions of the test compound, and incubated at 37° C. for 18 hours. The minimum inhibitory concentration (MIC) is equal to the concentration of the compound exhibiting 100% inhibition of growth of  P. multocida  as determined by comparison with an uninoculated control.  
           [0089]    Assay III  
           [0090]    This assay is based on the agar dilution method using a Steers Replicator. Two to five colonies isolated from an agar plate are inoculated into BHI broth and incubated overnight at 37° C. with shaking (200 rpm). The next morning, 300 μl of the fully grown  P. haemolytica  preculture is inoculated into 3 ml of fresh BHI broth and is incubated at 37° C. with shaking (200 rpm). The appropriate amounts of the test compounds are dissolved in ethanol and a series of two-fold serial dilutions are prepared. Two ml of the respective serial dilution is mixed with 18 ml of molten BHI agar and solidified. When the inoculated  P. haemolytica  culture reaches 0.5 McFarland standard density, about 5 μl of the  P. haemolytica  culture is inoculated onto BHI agar plates containing the various concentrations of the test compound using a Steers Replicator and incubated for 18 hours at 37° C. Initial concentrations of the test compound range from 100-200 μg/ml. The MIC is equal to the concentration of the test compound exhibiting 100% inhibition of growth of  P. haemolytica  as determined by comparison with an uninoculated control.  
           [0091]    The in vivo activity of the compounds of formula 1 can be determined by conventional animal protection studies well known to those skilled in the art, usually carried out in mice.  
           [0092]    Mice are allotted to cages (10 per cage) upon their arrival, and allowed to acclimate for a minimum of 48 hours before being used. Animals are inoculated with 0.5 ml of a 3×10 3  CFU/ml bacterial suspension ( P. multocida  strain 59A006) intraperitoneally. Each experiment has at least 3 non-medicated control groups including one infected with 0.1X challenge dose and two infected with 1X challenge dose; a 10X challenge data group may also be used. Generally, all mice in a given study can be challenged within 30-90 minutes, especially if a repeating syringe (such as a Cornwall® syringe) is used to administer the challenge. Thirty minutes after challenging has begun, the first compound treatment is given. It may be necessary for a second person to begin compound dosing if all of the animals have not been challenged at the end of 30 minutes. The routes of administration are subcutaneous or oral doses. Subcutaneous doses are administered into the loose skin in the back of the neck whereas oral doses are given by means of a feeding needle. In both cases, a volume of 0.2 ml is used per mouse. Compounds are administered 30 minutes, 4 hours, and 24 hours after challenge. A control compound of known efficacy administered by the same route is included in each test. Animals are observed daily, and the number of survivors in each group is recorded. The  P. multocida  model monitoring continues for 96 hours (four days) post challenge.  
           [0093]    The PD 50  is a calculated dose at which the compound tested protects 50% of a group of mice from mortality due to the bacterial infection which would be lethal in the absence of drug treatment.  
           [0094]    The compounds of formula 1 and their pharmaceutically acceptable salts (hereinafter referred to, collectively, as “the active compounds of this invention”) may be administered alone or in combination with pharmaceutically acceptable carriers, in either single or multiple doses. Suitable pharmaceutical carriers include inert solid diluents or fillers, sterile aqueous solutions and various organic solvents. The pharmaceutical compositions formed by combining the active compounds of this invention can then be readily administered in a variety of dosage forms such as tablets, powders, lozenges, syrups, injectable solutions and the like. These pharmaceutical compositions can, if desired, contain additional ingredients such as flavorings, binders, excipients and the like. Thus, for purposes of oral administration, tablets containing various excipeints such as sodium citrate, calcium carbonate and calcium phosphate may be employed along with various disintegrants such as starch, methylcellulose, alginic acid and certain complex silicates, together with binding agents such as polyvinylpyrrolidone, sucrose, gelatin and acacia. Additionally, lubricating agents such as magnesium stearate, sodium lauryl sulfate and talc are often useful for tabletting purposes. Solid compositions of a similar type may also be employed as fillers in soft and hard filled gelatin capsules. Preferred materials for this include lactose or milk sugar and high molecular weight polyethylene glycols. When aqueous suspensions or elixirs are desired for oral administration, the essential active ingredient therein may be combined with various sweetening or flavoring agents, coloring matter or dyes and, if desired, emulsifying or suspending agents, together with diluents such as water, ethanol, propylene glycol, glycerin and combinations thereof.  
           [0095]    For parenteral administration, solutions containing an active compound of this invention or a pharmaceutically acceptable salt thereof in sesame or peanut oil, aqueous propylene glycol, or in sterile aqueous solution may be employed. Such aqueous solutions should be suitably buffered if necessary and the liquid diluent first rendered isotonic with sufficient saline or glucose. These particular aqueous solutions are especially suitable for intravenous, intramuscular, subcutaneous and intraperitoneal administration. The sterile aqueous media employed are all readily available by standard techniques known to those skilled in the art.  
           [0096]    To implement the methods of this invention, an effective dose of an active compound of this invention is administered to a susceptible or infected animal (including mammals, fish and birds) by parenteral (i.v., i.m. or s.c.), oral, or rectal routes, or locally as a topical application to the skin and/or mucous membranes. The route of administration will depend on the mammal, fish or bird that is being treated. The effective dose will vary with the severity of the disease, and the age, weight and condition of the animal. However, the daily dose will usually range from about 0.25 to about 150 mg/kg body weight of the patient to be treated, preferably from about 0.25 to about 25 mg/kg.  
           [0097]    The Examples provided below illustrate specific embodiments of the invention, but the invention is not limited in scope to the Examples specifically exemplified.  
       
    
    
     EXAMPLE 1  
       [0098]    Compound of formula 1 wherein R is ethyl; R 2 , R 3 , and R 4  are each H, R 5  is methyl, R 6  is acetyl, R 7  is H, and R 1  is —(CH 2 ) 3- (4-pyridin-3-yl-imidazol-1-yl)  
         [0099]    To a compound of formula 1, wherein, R 2 =R 3 =R 4 =H, R 5 =methyl, R 6 =H, R 7 =H, and R 1 =—(CH 2 ) 3- (4-pyridin-3-yl-imidazol-1-yl), (575 mg, 0.69 mmol) in CH 2 Cl 2  (6.9 mL) at room temperature (about 20°-25° C.) was added Ac 2 O (72 μL, 0.76 mmol) and the resulting solution was stirred at room temperature for 2 hours. Saturated NaHCO 3  was added, the two layers were separated, the aqueous layer was extracted with CH 2 Cl 2 , and the combined organic layers were washed with brine, dried over anhydrous Na2SO4, and concentrated in vacuo to give the title compound as a white solid. MS m/z 868 (m+H) +   
       EXAMPLE 2  
       [0100]    Compound of formula 1 wherein R is ethyl; R 2 , R 3 , and R 4  are each H, R 5  is methyl, R 6  is acetyl, R 7  is F, and R 1  is —(CH 2 ) 3- (4-pyridin-3-yl-imidazol-1-yl)  
         [0101]    To a compound of formula 1, wherein, R 2 =R 3 =R 4 =H, R 5 =Me, R 6 =Ac, R 7 =H, R 1 =—(CH 2 ) 3- (4-pyridin-3-yl-1-imidazol-1-yl), prepared as described in Example 1, (72 mg, 0.08 mmol) in DMF (N,N-dimethylformamide) (1.7 mL) at −78° C. was added KHMDS (0.25 mL 0.50 M solution in toluene) and the resulting solution was stirred at −78° C. for 20 minutes. SELECT FLURO (Aldrich, 23 mg) was added and the resulting solution was stirred at −78° C. for 30 minutes. Water was added, the reaction was warmed to room temperature, and EtOAc was added. The two layers were separated, the aqueous layer was extracted with EtOAc, the combined organic layer was washed with brine, dried over anhydrous Na 2 SO 4 , and evaporated in vacuo to give the title compound as a white solid. MS m/z 886 (m+H) +   
       EXAMPLE 3  
       [0102]    Compound of formula 1 wherein R is ethyl, R 2 , R 3 , and R 4  are each H, R 5  is methyl, R 6  is H, R 7  is F, and R 1  is —(CH 2 ) 3- (4-pyridin-3-yl-imidazol-1-yl)  
         [0103]    To a compound of formula 1, wherein, R 2 =R 3 =R 4 =H, R 5 =Me, R 6 =Ac, R 7 =F, R 1 =—(CH 2 ) 3- (4-pyridin-3-yl-imidazol-1-yl), (80 mg) prepared as described in Example 2, was added methanol (1.0 mL), and the resulting solution was heated at 70° C. for 1 hour. MeOH was evaporated in vacuo, and the crude product was purified by preparative TLC (thin layer chromatography) (89% CH 2 Cl 2 /10% MeOH/1% NH 3 H 2 O) to give the title compound as a white solid.  
         [0104]    MS m/z 844 (m+H) +   
         [0105]    [0105] 13 C NMR (CDCl 3 , 100 MHz) δ 202.80 (d, J=27.2 Hz), 166.93 (d, J=23.0 Hz), 24.74 (d, J=21.5 Hz).  
         [0106]    [0106] 13 H NMR (CDCl 3 , 400 MHz) δ 1.77 (3H, d, J=J=21.6 Hz).