Method of treating or prevention of fibrillation of the heart

A method for the treatment and prevention of fibrillation using one or more potassium channel activators. Also, disclosed is a process for the preparation of compounds of the formula ##STR1## and the tautomeric forms ##STR2## wherein R''and R" are as defined herein.

FIELD OF THE INVENTION 
The present invention relates to novel compounds having potassium channel 
activating activity which are therefore, useful in the treatment of 
hypertension, and is additionally concerned with a method for preparing 
these and other compounds and a method of using potassium channel 
activators as antifibrillatory agents. 
BACKGROUND OF THE INVENTION 
Ischemia of the heart is the reduction of blood flow to cardiac tissue 
which can result in dysrhythmic conditions, e.g. ventricular arrhythmia 
and ventricular fibrillation, and cell death. Such dysrhythmic conditions 
are the result of the asynchronous excitability states created between 
normal and ischemic-injured cardiac cells which, in turn, caused a 
disruption of the normal ion transport channels within the cardiac tissue. 
Ventricular fibrillation is generally considered to be a severe extension 
of less harmful ventricular arrhythmias. Arrhythmia rises to the level of 
fibrillation when this disruption results in action potential and 
conduction inhomogeneities that critically desynchronize normal excitation 
and contraction coupling over a sufficient portion of the heart (Bacaner 
et al., "Potassium Channel Blockade: A Mechanism for Suppressing 
Ventricular Fibrillation", Proc. Nat'l. Acad. Sci. U.S.A., Vol. 
83:2223-2227, April 1986:Medical Sciences). 
However, despite the apparent link between arrhythmia and fibrillation, it 
has been found that lidocaine and procainamide, Class I antiarrhythmic 
agents, do not have antifibrillatory activity. These agents prevent 
ventricular arrhythmias but are unable to suppress ventricular 
fibrillation as disclosed by N. Cook, "The Pharmacology of Potassium 
Channels and Their Therapeutic Potential", TIPS, January 1988; Vol. 9: p. 
21-28. 
It is also interesting to note that similar results have been observed with 
certain anti-ischemic agents. For example, certain calcium channel 
blockers and thromboxane receptor antagonists have been identified as 
capable of significantly reducing infarct size and thus are potentially 
useful as anti-ischemic agents. Surprisingly, reduction of infarct size, 
accomplished via reperfusion (restoration of blood flow to previously 
injured cardiac tissue), does not dictate suppression of fibrillation. 
Likewise, reperfusion can be provided to an ischemic heart by various new 
surgical (bypass), mechanical (angioplasty) and thrombolytic means in a 
sufficiently timely fashion so as to save much of the ischemia-injured 
tissue. 
The Bacaner et al. report further discloses that bretylium and bethanidine 
have been found useful in decreasing conduction inhomogeneities in the 
ischemic-injured heart resulting in an increase in action potential 
duration and decreased fibrillation. This antifibrillatory action is 
attributed to blockade of one or more of the potassium channels in the 
cells of the heart. Thus, potassium channel blockers are expected as a 
class to be useful as antifibrillatory agents. In fact, P. Siegl, et al., 
"Effects of ATP-Sensitive Potassium Channel Modulators, Glyburide and BRL 
4915, on Ischemia-Induced Fibrillation in Isolated Rat Hearts", FASEB 
Journal, Vol. 3, #3, A3607 (1989), have observed profibrillatory activity 
for potassium channel activators such as pinacidil and BRL 34915 
(cromakalim). 
Petersen, in U.S. Pat. No. 4,057,636, discloses compounds of the formula 
##STR3## 
wherein R.sub.2 can be hydrogen, halogen, hydroxy, lower alkyl or lower 
alkoxy. These compounds are stated to be useful as antihypertensive 
agents. 
Petersen et al., in "Synthesis and Hypotensive Activity of 
N-Alkyl-N"-Cyano-N'-Pyridylguanidines", Journal of Medicinal Chemistry, 
1978, Vol. 21, No. 8, disclose compounds as above in U.S. Pat. No. 
4,057,636 but wherein the pyridyl group has been replaced by a phenyl 
ring. Petersen et al. further disclose that such phenyl compounds are 
either inactive or only weakly active as antihypertensive agents. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there is disclosed a method for 
the treatment and prevention of fibrillation using one or more potassium 
channel activators. Also, there is disclosed a process for the preparation 
of compounds of the formula 
##STR4## 
and the tautomeric forms 
##STR5## 
wherein R' is selected from hydrogen, alkyl, aryl, arylalkyl, pyridyl, 
alkenyl, alkynyl, haloalkyl, cycloalkyl, arylalkyl, cycloalkylalkyl, 
##STR6## 
heterocyclo, heterocycloalkyl or substituted alkyl wherein the 
substituents are selected from alkoxy, alkylthio and substituted amino; 
R" is selected from alkyl, aryl, pyridyl, alkenyl, alkynyl, haloalkyl, 
cycloalkyl, arylalkyl, cycloalkylalkyl, or 
##STR7## 
R.sub.1 is alkyl, alkenyl, alkynyl, haloalkyl, cycloalkyl, aryl, arylalkyl 
or cycloalkylalkyl; 
R.sub.2 is --C.tbd.N, --NO.sub.2, 
##STR8## 
R.sub.3 and R.sub.4 are each independently selected from -R.sub.2, 
hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, halo, alkoxy, --NHalkyl, 
--N--(alkyl).sub.2, --S--alkyl, --O--arylalkyl, --S--arylalkyl or 
--S--aryl, --O--aryl, --NHarylalkyl, or R.sub.2 and R.sub.3 taken together 
are a group which forms a ring with the two carbon atoms to which they are 
attached, which group is selected from 
##STR9## 
wherein m=1 or 2, 
n=1-3, 
p=0-2, 
X is O, NR.sub.5, CH.sub.2 ; 
R.sub.5 is hydrogen or R.sub.1 ; 
a, b, and c are all carbons or one of a, b and c can be nitrogen or --NO-- 
and the others are carbons; 
X is selected from a single bond, --O--, --S--, --SO--, --SO.sub.2 --, 
--CH.sub.2 -- or --NX.sub.7 where X.sub.7 is H or C.sub.1-4 alkyl; 
X.sub.2 is hydrogen, hydroxy, 
##STR10## 
X.sub.3 and X.sub.4 are each independently hydrogen, alkyl or arylalkyl, 
or, X.sub.3 and X.sub.4 taken together with the carbon atom to which they 
are attached form a 5- to 7-membered carbocyclic ring; 
X.sub.5 is selected from H, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, 
arylalkyl, cycloalkylalkyl, --CN, --NO.sub.2, --COR, --COOR, --CONHR, 
--CONR.sub.2, --CF.sub.3, S--alkyl, --SOalkyl, --SO.sub.2 alkyl, 
##STR11## 
X.sub.5 ', halogen, amino, substituted amino, O--alkyl, OCF.sub.3, 
OCH.sub.2 CF.sub.3, --OCOalkyl, --OCONX.sub.5 'alkyl, --NX.sub.5 'COalkyl 
and NX.sub.5 'COOalkyl, NX.sub.5 'CONX.sub.2 wherein X.sub.5 ' in each of 
the above groups can be hydrogen, alkyl, aryl, arylalkyl, cycloalkyl, or 
(cycloalkyl)alkyl; 
X.sub.6 is selected from H, alkyl, OH, O-alkyl, amino, substituted amino, 
CN, and NO.sub.2 ; 
which process comprises 
a) reacting a compound of the formula 
EQU R'--N.dbd.C.dbd.S 
with a compound of the formula 
EQU M.sup.+ HN--C.tbd.N 
(wherein M.sup.+ is an alkali metal) in a solvent; and either 
b) thereafter providing treatment with a carbodiimide of the formula 
##STR12## 
wherein R.sub.6, R.sub.7 and R.sub.8 are alkyl, cycloalkyl, phenyl, 
phenylalkyl, cycloalkylalkyl or R.sub.6 and R.sub.7 taken together with 
the nitrogen atom to which they are attached are 1-pyrrolidinyl, 
1-piperidinyl, 4-morpholinyl, 4-thiomorpholinyl, 4-alkyl-1-piperazinyl, 
4-phenylalkyl-1-piperazinyl; and x is halo; and an amine of formula 
R"NH.sub.2 in the presence of a polar solvent to provide the desired 
product; or, 
c) isolating a compound formed by step (a) having the formula 
##STR13## 
and thereafter following step (b) to provide the desired product.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
It has been found that compounds of the present invention, and potassium 
channel activators in general, are useful as antifibrillatory agents. 
The present invention also provides a novel process for preparing compounds 
of the formula 
##STR14## 
and its tautomers. 
The term lower alkyl used in defining various symbols refers to straight or 
branched chain saturated hydrocarbon radicals having up to eight carbons, 
preferably from one to five carbons. Similarly, the terms lower alkoxy and 
lower alkylthio refer to such lower alkyl groups attached to an oxygen or 
sulfur. 
The term lower alkenyl refers to straight or branched chain hydrocarbon 
radicals having from two to eight carbons and one double bond, preferably 
three to five carbons. The term lower alkynyl refers to straight or 
branched chain hydrocarbon radicals having from two to eight carbons and 
one triple bond, preferably three to five carbons. 
The term cycloalkyl refers to saturated carbocyclic rings of 4 to 7 carbon 
atoms with cyclopentyl and cyclohexyl being most preferred. 
The term halo refers to chloro, bromo and fluoro. 
The term halo substituted lower alkyl refers to such lower alkyl groups 
described above in which one or more hydrogens have been replaced by 
chloro, bromo or fluoro groups such as trifluoromethyl, which is 
preferred, pentafluoroethyl, 2,2,2-trichloroethyl, chloromethyl, 
bromomethyl, etc. 
The term aryl refers to phenyl or mono substituted phenyl, wherein said 
substituent is lower alkyl of 1 to 4 carbons, lower alkylthio of 1 to 4 
carbons, lower alkoxy of 1 to 4 carbons, halo, nitro, cyano, hydroxy, 
amino, --NH--alkyl wherein alkyl is of 1 to 4 carbons, --N(alkyl).sub.2 
wherein alkyl is of 1 to 4 carbons, --CF.sub.3, --OCHF.sub.2, 
##STR15## 
(wherein R.sub.6 is hydrogen, lower alkyl of 1 to 4 carbons, lower alkoxy 
of 1 to 4 carbons, lower alkylthio of 1 to 4 carbons, halo, hydroxy or 
CF.sub.3), --O--CH.sub.2 --cycloalkyl, or --S--CH.sub.2 --cycloalkyl, and 
di-substituted phenyl, wherein said substituents are selected from methyl, 
methoxy, methylthio, halo, CF.sub.3, nitro, amino, and OCHF.sub.2. 
The term "substituted amino" refers to a group of the formula --NZ.sub.1 
Z.sub.2 wherein Z.sub.1 is hydrogen, alkyl, cycloalkyl, aryl, arylalkyl, 
cycloalkylalkyl and Z.sub.2 is alkyl, cycloalkyl, aryl, arylalkyl, 
cycloalkylalkyl or Z.sub.1 and Z.sub.2 taken together with the nitrogen 
atom to which they are attached are 1-pyrrolidinyl, 1-piperidinyl, 
1-azepinyl, 4-morpholinyl, 4-thiamorpholinyl, 1-piperazinyl, 
4-alkyl-1-piperazinyl, 4-arylalkyl-1-piperazinyl, 
4-diarylalkyl-1-piperazinyl, 1-pyrrolidinyl, 1-piperidinyl, or 1-azepinyl 
substituted with alkyl, alkoxy, alkylthio, halo, trifluoromethyl or 
hydroxy. 
To prepare the compounds of formula A in accordance with the present 
process, a compound of the formula 
EQU R'--N.dbd.C.dbd.S 
is reacted with a cyanamide of the formula 
EQU M.sup.+ NH--C.tbd.N 
(where M is an alkali metal, e.g, sodium or potassium) in the presence of a 
solvent, e.g. ethanol, or with cyanamide (e.g., H.sub.2 --C.tbd.N) and an 
organic base such as triethylamine, to provide a compound of the formula 
##STR16## 
The present process utilizes a carbodiimide of the formula 
##STR17## 
wherein R.sub.6, R.sub.7 and R.sub.8 are alkyl, cycloalkyl, phenyl, 
phenylalkyl, cycloalkylalkyl and R.sub.6 and R.sub.7 taken together with 
the nitrogen atom to which they are attached are 1-pyrrolidinyl, 
1-piperidinyl, 4-morpholinyl, 4-thiomorpholinyl, 4-alkyl-1-piperazinyl, 
4-phenylalkyl-1-piperazinyl and x is halo. 
Reaction of compound D with a compound of formula E and an amine of formula 
R"NH.sub.2, in a polar solvent, such as dimethylformamide, provides the 
corresponding compounds of formula A. 
Compounds of formula A can also be prepared without isolating the 
intermediates of formula D by reacting a compound of formula B with a 
compound of formula C in a solvent, such as ethanol, followed by treatment 
with compound E and an amine of formula R"NH.sub.2, as described above. 
Preparation of cyanoguanidine analogs of compound A is known using 
dicyclohexylcarbodiimide but this reaction takes 6-7 days to complete. 
(See "Synthesis of N-Alkyl-N-Cyano-4-Pyridylguanidines From 
4-Pyridylthiocarbamic Acid via N-Alkyl-N'-4-Pyridylthioureas, or via 
4-Pyridylcyaniminothiocarbamic Acid", E. T. Hansen and H. J. Peterson, 
Synthetic Communications, 14(13), 1275-1283 (1984)). While compounds of 
the present invention have been made using the prior art process, it took 
7 days to achieve yields of less than 5%. Alternate prior art processes 
offer some improvement, but still take 1-2 days to provide yields in the 
20% range. The novel process of the present invention provides a dramatic 
enhancement in the rate of the reaction and gives high yields of compounds 
of formula A as will be more clearly illustrated in the examples. 
If any of R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 or X.sub.1 
-X.sub.6 in the above reactions are aryl or arylalkyl wherein aryl is 
phenyl substituted with one hydroxy or one or more amino groups, or a 
substituted alkyl such as hydroxylalkyl, aminoalkyl or mercaptoalkyl, then 
the hydroxyl, amino, or mercaptan function should be protected during the 
reaction. Suitable protecting groups include benzyloxycarbonyl, 
t-butoxycarbonyl, benzyl, benzhydryl, etc. The protecting group is removed 
by hydrogenation, treatment with acid, or by other known means following 
completion of the reaction. 
The thioureas of formula B can be prepared by heating an isothiocyanate of 
the formula 
EQU R'--N.dbd.C.dbd.S 
with either monosodium cyanamide or with cyanamide in the presence of an 
organic base, such as triethyl amine, or can be prepared by standard 
methods described in the literature, such as by C. R. Rasmussen, F. J. 
Villani, Jr., L. E. Weaner, B. E. Reynolds, A. R. Hood, L. R. Hecker, S. 
O. Nortey, A. Hanslin, M. J. Costanzo, E. T. Powell, A. J. Molinari, 
Synthesis, 1988, p. 456, and V. V. Mozolis and S. P. Locubaitite, Russian 
Chemical Reviews, 1973, 42, 587. 
Compounds of the formula R"NH.sub.2 where R" is 
##STR18## 
can be prepared by methods described in the literature, such as by J. M. 
Evans, C. S. Fake, T. C. Hamilton, R. H. Poyser, E. A. Watts, J. Med. 
Chem. 1983, 26, 1582 and J. Med. Chem. 1986, 29, 2194; R. W. Lang, P. F. 
Wenk, Helvetica Chimica Acta, 1988, 71, 596; EP 0205292 A2 (1986), and WO 
87/07607. 
Compounds of the formula R"NH.sub.2 where R" is 
##STR19## 
can be prepared from a ketone of the formula 
##STR20## 
by standard methodology. The above ketone can be obtained by literature 
procedures, such as disclosed by P. Sebok and T. Timar, Heterocycles, 
1988, 27, 2595; P. Teixidor et al., Heterocycles, 1988, 27, 2459; A. 
Benerji and N. C. Goomer, Tetrahedron Letters, 1979, 3685; G. Ariamala and 
K K Subramanian, Tetrahedron Letters, Vol. 29, No. 28, p. 3487-3488 
(1988). 
Compounds of the formula R"NH.sub.2 where R" is 
##STR21## 
and X.sub.1 is --NH-- are described in PCT Patent Application WO 85/00602. 
Compounds of the formula R"NH.sub.2 where R" is 
##STR22## 
and X.sub.1 is --S--, --SO-- or --SO.sub.2 are described in European 
Patent Application EP 322 251 A. 
Compounds of the formula R"NH.sub.2 where R" is 
##STR23## 
and X.sub.1 is --CH.sub.2 -- can be prepared as described in European 
Patent Application EP 168 619 A. 
Compounds of the formula R"NH.sub.2 where R" is 
##STR24## 
and X.sub.1 is a single bond can be prepared as described in European 
Patent Application EP 321 175 A. 
In preferred embodiments the present process is used to prepare compounds 
such as 
##STR25## 
where R" can be t-butyl, t-pentyl or sec-3,3-dimethylbutyl; or 
##STR26## 
As mentioned above, the present invention further encompasses the use of 
potassium channel activators as antifibrillatory agents. This is 
unexpected since the prior art, as described above, predicts that 
potassium channel blockers are antifibrillatory and, in fact, that certain 
potassium channel activators have pro-fibrillatory tendencies. 
Surprisingly, it has been found that potassium channel activators are 
useful as antifibrillatory agents. Therefore the present method comprises 
preventing or treating fibrillation of the heart in a mammaliam species by 
the administration of a therapeutically effective amount of one or more 
potassium channel activators. In a preferred embodiment this novel method 
comprises administering potassium channel activators prior to or during 
reperfusion, it being understood that such reperfusion can be the result 
of occlusion removal (e.g., by surgical, angioplasty or thrombolytic 
means) and/or from treatment with anti-ischemic agents. 
Further, since it is now known that potassium channel activators are also 
useful as anti-ischemic agents, as has been disclosed in U.S. Ser. No. 
220,866 (HA474), concurrent ischemia and fibrillation can be treated by 
the administration of potassium channel activators. 
Any potassium channel activator may be used in accordance with the present 
invention. Suitable potassium channel activators include those disclosed 
in U.S. Pat. No. 4,057,636, especially the compound 
##STR27## 
known as pinacidil; those disclosed in European Patent Application 0 274 
821, especially the compound 
##STR28## 
known as cromakalim; nicorandil; minoxidil; compounds in copending 
application U.S. Ser. No. 506,632 filed Apr. 9, 1990 having the formula 
##STR29## 
wherein a, b, and c are all carbons or one of a, b and c can be nitrogen 
or --NO-- and the others are carbons; 
R.sub.1 is 
##STR30## 
R.sub.2 is hydrogen, hydroxy, 
##STR31## 
R.sub.3 and R.sub.4 are each independently hydrogen, alkyl or arylalkyl, 
or, R.sub.3 and R.sub.4 taken together with the carbon atom to which they 
are attached form a 5- to 7-membered carbocyclic ring; 
R.sub.5 is selected from H, alkyl, haloalkyl, alkenyl, alkynyl, cyoloalkyl, 
arylalkyl, cycloalkylalkyl, --CN, --NO.sub.2, --COR, --COOR, --CONHR, 
--CONR.sub.2, --CF.sub.3, S--alkyl, --SOalkyl, --SO.sub.2 alkyl, 
##STR32## 
halogen, amino, substituted amino, O--alkyl, OCF.sub.3, OCH.sub.2 
CF.sub.3, --OCOalkyl, --OCONRalkyl, --NRCOalkyl and NRCOOalkyl, 
NRCONR.sub.2 wherein R in each of the above groups can be hydrogen, alkyl, 
aryl, arylalkyl, cycloalkyl, or (cycloalkyl)alkyl; 
R.sub.6 is selected from H, alkyl, OH, O--alkyl, amino, substituted amino, 
CN, and NO.sub.2 ; 
R.sub.7 and R.sub.8 are each independently selected from hydrogen, alkyl, 
alkenyl, aryl, (heterocyclo)alkyl, heterocyclo, arylalkyl, cycloalkyl and 
(cycloalkyl)alkyl, substituted alkyl wherein the substituents include 
alkoxy, alkylthio and substituted amino, or R.sub.7 and R.sub.8 taken 
together with the nitrogen atom to which they are attached form 
1-pyrrolidinyl, 1-piperidinyl, 1-azepinyl, 4-morpholinyl, 
4-thiamorphilinyl, 1-piperazinyl, 4-alkyl-1-piperazinyl or 
4-arylalkyl-1-piperazinyl, wherein each of the so-formed groups can be 
substituted with alkyl, alkoxy, alkylthio, halogen or trifluoromethyl; 
R.sub.9 and R.sub.10 are selected from hydrogen, alkyl, alkenyl, aryl, 
arylalkyl, cycloalkyl or cycloalkylalkyl; and 
n is 1, 2 or 3; 
with the compound 
##STR33## 
being preferred; compounds in copending application U.S. Ser. No. 349,021 
filed May 8, 1989 having the formula 
##STR34## 
and its possible tautomers 
##STR35## 
wherein R.sub.1 is alkyl, alkenyl, alkynyl, haloalkyl, cycloalkyl, aryl, 
arylalkyl or cycloalkylalkyl; 
R.sub.2 is --C.tbd.N, --NO.sub.2, 
##STR36## 
R.sub.3 and R.sub.4 are each independently selected from -R.sub.2, 
hydrogen, alkyl, alkenyl, alkynyl, haloalkyl, halo, alkoxy, --NHalkyl, 
--N--(alkyl).sub.2, --S--alkyl, --O--arylalkyl, --S--arylalkyl or 
--S--aryl, --O--aryl, --NHarylalkyl, or R.sub.2 and R.sub.3 taken together 
are a group which forms a ring with the two carbon atoms to which they are 
attached, which group is selected from 
##STR37## 
wherein m=1 or 2, 
n=1-3, 
p=0-2, 
X is O, NR.sub.5, CH.sub.2 ; and 
R.sub.5 is hydrogen or R.sub.1 ; 
and compounds of the formula 
##STR38## 
wherein A can be --CH.sub.2 --, --O--, --NR.sub.9 --, --S--, --SO-- or 
--SO.sub.2 --, where R.sub.9 is hydrogen or lower alkyl of 1 to 4 carbons; 
wherein 
X is oxygen or sulfur; 
Y is --NR.sub.8, --O--, --S-- or 
##STR39## 
R.sub.1 is aryl, arylalkyl, heterocyclo or (heterocyclo)alkyl; R.sub.2 is 
hydrogen, hydroxy, 
##STR40## 
R.sub.3 and R.sub.4 are each independently hydrogen, alkyl or arylalkyl, 
or, R.sub.3 and R.sub.4 taken together with the carbon atom to which they 
are attached form a 5- to 7-membered carbocyclic ring; 
R.sub.5 is selected from H, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, 
arylalkyl, cycloalkylalkyl, --CN, --NO.sub.2, --COR, --COOR, --CONHR, 
--CONR.sub.2, --CF.sub.3, S--alkyl, --SOalkyl, --SO.sub.2 alkyl, 
##STR41## 
halogen, amino, substituted amino, O-alkyl, OCF.sub.3, OCH.sub.2 
CF.sub.3, --OCOalkyl, --OCONRalkyl, --NRCOalkyl and NRCOOalkyl, 
NRCONR.sub.2 wherein R in each of the above groups can be hydrogen, alkyl, 
aryl, arylalkyl, cycloalkyl, or (cycloalkyl)alkyl; 
R.sub.6 is selected from H, alkyl, halo, OH, O--alkyl, amino and 
substituted amino; 
R.sub.7 and R.sub.8 are each independently selected from hydrogen, alkyl, 
arylalkyl; 
n is 1, 2 or 3; and, 
R.sub.10 is hydrogen, hydroxy, alkyl or O--alkyl. 
In carrying out the method of the present invention, the potassium channel 
activator may be administered to mammalian species, such as monkeys, dogs, 
cats, rats, humans, etc., during the period of fibrillation and/or prior 
to or during the period of reperfusion and/or shortly after termination of 
an ischemic attack, for example, within 1 to 2 hours after the ischemia. 
Although the potassium channel activator may be administered systemically, 
such as orally or parenterally, it is preferred that the potassium channel 
activator be administered locally to the coronary arteries by catheter 
such as by arterial angiography or intracoronary injection. 
With regard to dosage of potassium channel activator, where the drug is 
administered by arterial angiography or intracoronary injection, from 
about 0.001 to about 30 mg/kg/treatment and preferably from about 0.5 to 
about 25 mg/kg/treatment will be employed. The number of treatments will 
depend upon the severity of the fibrillation and the progress of 
reperfusion to achieve normal heart rhythm. Usually, from 1 to 5 
treatments per day will be required for as long as fibrillation continues. 
Where the potassium channel activator is to be administered by angiography 
or intracoronary injection, it will be formulated in a conventional 
vehicle, such as distilled water, saline, Ringer's solution, or other 
conventional carriers. 
The potassium channel activator may also be incorporated in a conventional 
dosage form, such as a tablet, capsule, elixir or injectable. The above 
dosage forms will also include the necessary carrier material, excipient, 
lubricant, buffer, antibacterial, bulking agent (such as mannitol), 
anti-oxidants (ascrobic acid of sodium bisulfite) or the like. Oral dosage 
forms are preferred, although parenterial forms are quite satisfactory as 
well. 
With regiard to such systemic formulations, single or divided doses of from 
about 5 to about 2500 mg, preferably from about 10 to 2000 mg/one to four 
times daily, may be administered in systemic dosage forms as described 
above for a period sufficient to restore normal heart function. 
The present invention will be further illustrated by the following examples 
but should not be limited to the details described therein. 
EXAMPLE 1 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)aminomethyl]amino]benzonitrile 
A. N-Cyano-N'-(4-cyanophenyl)thiourea 
A suspension of 4-cyanophenyl isothiocyanate (10.75 g, 67.2 mmol) and 
monosodium cyanamide (4.30 g, 67.2 mmol) in absolute ethanol (35 ml) was 
heated at 90.degree. C. (oil bath) for 3.0 hours under argon. The reaction 
was then cooled (ice bath) and filtered to give the title A compound as a 
gray-white solid (9.92 g), m.p. &gt;230.degree. C. TLC (10% MeOH/CH.sub.2 
Cl.sub.2) single spot, R.sub.f =0.08. 
B. N-Cyano-N'-(4-cyanophenyl)carbamidothioic acid methyl ester, 
methylsulfate 
A suspension of thiourea of the title A compound (9.00 g, 44.5 mmol) in 
tetrahydrofuran/dimethylformamide (44 ml each) was treated with dimethyl 
sulfate (4.43 ml, 46.7 mmol) dropwise over five minutes under argon. 
Within a few minutes the suspension became a clear solution. After 
stirring overnight, the reaction was partially evaporated and diluted with 
ether. The solids which precipitated were filtered to give the title B 
compound as a white solid (11.45 g), m.p. 194.degree.-202.degree. C. TLC 
(10% MeOH/CH.sub.2 Cl.sub.2) single spot, R.sub.f =0.41. 
C. 4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile 
A mixture of the title B compound (11.40 g, 40.8 mmol) and 
2-amino-3,3-dimethyl butane (13.7 ml, 102 mmol) in isopropanol (82 ml) was 
heated at 90.degree. C. (oil bath) under argon overnight. The reaction was 
then cooled and evaporated. The residue was partitioned between ethyl 
acetate and 10% citric acid solution. The organic phase was washed with 
water, saturated sodium chloride, dried over anhydrous magnesium sulfate, 
and evaporated. Flash chromatography of the residue (9.32 g) over Merck 
silica (1000 ml) eluting with 30% acetone/hexane gave a white solid (3 g). 
Crystallization from isopropanol (twice) gave the title compound as 
free-flowing, white crystals (1.15 g), m.p. 191.degree.-192.degree. C. TLC 
(40% Acetone/Hexane) single spot, R.sub.f =0.41. TLC (15% EtOAc/CH.sub.2 
Cl.sub.2) single spot, R.sub.f =0.15. 
Microanalysis for C.sub.15 H.sub.19 N.sub.5 : Calc'd: C, 66.88; H, 7.11; N, 
26.01; Found: C, 66.86; H, 7.30; N, 25.90. 
N"-Cyano-N-(4-nitrophenyl)-N'-(1,2,2-tri-methylpropyl)guanidine 
A. N-Cyano-N'-(4-nitrophenyl)thiourea 
A suspension of 4-nitrophenyl isothiocyanate (10.0 g, 55.5 mmol) and 
monosodium cyanamide (3.55 g, 55.5 mmol) in absolute ethanol (30 ml) was 
heated at 90.degree. C. (oil bath) for 3.0 hours under argon. The reaction 
was then cooled (ice bath) and filtered to give a yellow solid (7.4 g), 
m.p.&gt;230.degree. C. TLC (10% MeOH/CH.sub.2 Cl.sub.2) single spot, R.sub.f 
=0.08. 
B. N-Cyano-N'-(4-nitrophenyl)carbamidothioic acid, methyl ester, methyl 
sulfate 
A suspension of thiourea of the title A compound (6.3 g, 28.35 mmol) in 
dimethylformamide (15 ml) was treated with dimethyl sulfate (2.8 ml, 29.8 
mmol) dropwise over five minutes under argon. Within a few minutes the 
suspension became a clear solution. After stirring overnight, the reaction 
was diluted with ether. The solids which precipitated were filtered to 
give the title B compound (8.68 g) as a white-solid, m.p. 
165.degree.-167.degree. C. TLC (40% acetone/hexanes) single spot, R.sub.f 
=0.25. 
C. N"-Cyano-N-(4-nitrophenyl)-N'-(1,2,2-trimethylpropyl)guanidine 
A mixture of title B compound (8.5 g, 25.8 mmol) and 2-amino-3,3-dimethyl 
butane (10.4 ml, 77.4 mmol) in isopropanol (80 ml) was heated at 
90.degree. C. (oil bath) under argon overnight. The reaction was then 
cooled and evaporated. The residue was partitioned between ethyl acetate 
and 10% citric acid solution. The organic phase was washed with water, 
saturated sodium chloride, dried over anhydrous magnesium sulfate, and 
evaporated. Flash chromatography of the residue (9.32 g) over Merck silica 
gel eluting with 20% acetone/hexane gave a yellow solid. Crystallization 
from isopropanol gave the desired product as a yellow solid (1.12 g), m.p. 
211.degree.-212.degree. C. TLC (40% Acetone/Hexane) single spot, R.sub.f 
=0.4. 
Microanalysis for C.sub.14 H.sub.19 N.sub.5 O.sub.2 : Calc'd: C, 58.11; H, 
6.62; N, 24.21; Found: C, 58.01; H, 6.60; N, 24.04. 
EXAMPLE 3 
N"-Cyano-N-(3-nitrophenyl)-N'-(1,2,2-tri-methylpropyl)guanidine 
A. N-Cyano-N'-(3-nitrophenyl)thiourea 
A suspension of 4-nitrophenyl isothiocyanate (10.0 g, 55.5 mmol) and 
monosodium cyanamide (3.55 g, 55.5 mmol) in absolute ethanol (30 ml) was 
heated at 90.degree. C. (oil bath) for 3.0 hours under argon. The reaction 
was then cooled (ice bath) and &gt;210.degree. C. 
B. N-Cyano-N'-(3-nitrophenyl)carbamidothioic acid, methyl ester, methyl 
sulfate 
A suspension of thiourea of the title A compound (9.6 g, 43.2 mmol) in 
dimethylformamide (25 ml) was treated with dimethyl sulfate (4.3 ml, 45.3 
mmol) dropwise over five minutes under argon. Within a few minutes the 
suspension became a clear solution. After stirring overnight, the reaction 
was diluted with ether. The solids which precipitated were filtered to 
give the title B compound (16.07 g) as a white solid, m.p. &gt;210.degree. C. 
(softens at 152.degree. C.). TLC (40% acetone/hexanes) single spot, 
R.sub.f =0.1. 
C. N"-Cyano-N-(3-nitrophenyl)-N'-(1,2,2-trimethylpropyl)guanidine 
A mixture of the title B compound (16.0 g, 43.2 mmol) and 
2-amino-3,3-dimethyl butane (17.4 ml, 129.6 mmol) in isopropanol (45 ml) 
was heated for 6 hours at 90.degree. C. (oil bath) under argon. The 
reaction was then cooled and evaporated. The residue was partitioned 
between ethyl acetate and 10% citric acid solution. The organic phase was 
washed with water, saturated sodium chloride, dried over anhydrous 
magnesium sulfate, and evaporated. The residue was purified by flash 
chromatography (5-25% ethyl acetate in dichloromethane) to yield a yellow 
solid. It was crystallized from isopropanol to give the desired product as 
a colorless solid (0.98 g), m.p. 183.degree.-184.degree. C. TLC (35% 
Acetone/Hexane) single spot, R.sub.f =0.25. 
Microanalysis for C.sub.14 H.sub.19 N.sub.5 O.sub.2 : Calc'd: C, 58.11; H, 
6.62; N, 24.21; Found: C, 58.05; H, 6.72; N, 24.19. 
The following examples illustrate the novel process of the present 
invention. 
EXAMPLE 4 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile 
A mixture of the title A compound from Example 1 (404 mg, 2.0 mmol), 
diisopropylethylamine (0.4 mL) and 2-amino-3,3-dimethyl butane (0.35 ml, 
2.4 mmol) in dimethylformamide (3 ml) at room temperature was treated with 
1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (400 mg, 2.3 
mmol) and allowed to stir for 15 minutes. The reaction was then 
partitioned between 1N hydrochloric acid and ethyl acetate. The organic 
phase was washed with water and saturated sodium chloride solution, and 
dried over anhydrous magnesium sulfate. Evaporation and crystallization of 
the product from isopropanol gave a colorless solid (400 mg), m.p. 
188.degree.-190.degree. C. TLC (40% Acetone/Hexane) single spot, R.sub.f 
=0.42. 
Microanalysis for C.sub.15 H.sub.19 N.sub.5 : Calc'd: C, 66.88; H, 7.11; N, 
26.01; Found: C, 66.52; H, 7.10; N, 25.90. 
EXAMPLE 5 
N"-Cyano-N-(2-nitrophenyl)-N'-(1,2,2-trimethylpropyl)guanidine 
A mixture of 2-nitrophenyl isothiocyanate (6.00 g, 33 mmol) and monosodium 
cyanamide (1.92 g, 30 mmol) in dioxane (15 ml) was heated at 85.degree. C. 
(oil bath) overnight under argon. The reaction was then diluted with 
dimethylformamide (15 ml). Diisopropylethylamine (2.76 ml, 33 mmol) and 
2-amino-3,3-dimethyl butane (2.36 ml, 33 mmol) were added, and the 
resulting mixture was treated with 
1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (7.68 g, 44 
mmol). After stirring for 1 hour, the reaction was partitioned between 
ethyl acetate and 1N hydrochloric acid. The organic phase was washed with 
water (four times) and saturated sodium chloride solution, dried over 
anhydrous magnesium sulfate, and evaporated. The crude product was flash 
chromatographed (4% EtOAc/CH.sub.2 Cl.sub.2) over Merck silica (650 g). 
The fractions containing the desired product were combined and evaporated 
to give the title compound as a yellow oil (4.96 g) which was crystallized 
to give free-flowing yellow crystals (2.31 g), m.p. 
116.degree.-118.degree. C. TLC (40% Acetone/Hexane) single spot, R.sub.f 
=0.33. TLC (10% EtOAc/CH.sub.2 Cl.sub.2) single spot, R.sub.f =0.49. 
Microanalysis for C.sub.14 H.sub.19 N.sub.5 O.sub.2 : Calc'd: C, 58.11; H, 
6.62; N, 24.21; Found: C, 58.10; H, 6.55; N, 24.10. 
EXAMPLE 6 
3-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]benzonitrile 
A suspension of 3-cyanophenyl isothiocyanate (2.0 g, 12.48 mmol) and 
monosodium cyanamide (726 mg, 11.35 mmol) in absolute ethanol (10 ml) was 
heated at 100.degree. C. (oil bath) overnight under argon. The reaction 
was then cooled to room temperature, diluted with dimethylformamide (11 
mL) and treated with 2-amino-3,3-dimethylbutane (1.7 mL, 12.5 mmol) 
followed by 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride 
(4.35 g, 22.7 mmol). The reaction was stirred at room temperature for 1 
hour and partitioned between 1N hydrochloric acid and ethyl acetate. The 
organic phase was washed with water, saturated sodium chloride, dried over 
anhydrous magnesium sulfate, and evaporated. The residue, after 
evaporation of the solvent, was purified by flash chromatography over 
Merck silica gel (20% acetone in hexane) to give a colorless solid (890 
mg). Crystallization from chloroformisopropyl ether gave the title 
compound as a colorless solid, m.p. 172.degree.-173.degree. C. TLC (40% 
Acetone/Hexane) single spot, R.sub.f =0.45. 
Microanalysis for C.sub.15 H.sub.19 N.sub.5 : Calc'd: C. 66.88; H, 7.11; N, 
26.01; Found: C, 66.54; H, 7.04; N, 25.75. 
EXAMPLE 7 
N"-Cyano-N-(4-cyanophenyl)-N'-(1,1-dimethylethyl)guanidine 
A solution of the title A compound from Example 1 (2.02 g, 10.0 mmol) and 
1,1-dimethylethyl amine (1.26 mL, 12.0 mmol) in dimethylformamide (5 mL) 
was treated with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide 
hydrochloride (2.52 g, 13.0 mmol) at room temperature under argon. After 2 
hours, the reaction was partitioned between ethyl acetate and water. The 
aqueous layer was reextracted with ethyl acetate, and combined extracts 
were washed with 1N HCl, water and brine. After drying over anhydrous 
magnesium sulfate, the solvent was evaporated and the residue was purified 
by flash chromatography on silica gel (30% acetone in hexanes) to yield a 
colorless solid (1.12). The product was recrystallized from acetonitrile 
to provide the title compound as a colorless solid, m.p. 
184.degree.-185.degree. C. 
Analysis calc'd for C.sub.13 H.sub.15 N.sub.5 : C, 64.71; H, 6.27; N, 
29.02; Found: C, 64.41; H, 6.21; N, 28.80. 
EXAMPLE 8 
N"-Cyano-N-(4-cyanophenyl)-N'-(1,1-dimethylpropyl)guanidine 
A solution of the title A compound from Example 1 (3.0 g, 14.8 mmol) and 
t-amyl amine (1.9 mL, 16.3 mmol) in dimethylformamide (15 mL) was treated 
with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (3.4 g, 
16.3 mmol) at room temperature under argon. After 45 minutes, the reaction 
was partitioned between ethyl acetate and water. The aqueous layer was 
reextracted with ethyl acetate, and combined extracts were washed with 1N 
HCl, water and brine. After drying over anhydrous magnesium sulfate, the 
solvent was evaporated and the residue was purified by flash 
chromatography on silica gel (5% ethyl acetate in dichloromethane). The 
resulting colorless solid (1.4 g) was recrystallized from 
isopropanolisopropyl ether to provide the title compound, m.p. 
137.degree.-138.degree. C. 
Analysis calc'd for C.sub.14 H.sub.17 N.sub.5 : C, 65.85; H, 6.71; N, 
27.44; Found: C, 65.68; H, 6.67; N, 27.12. 
EXAMPLES 9-32 
Employing the procedures of Examples 2 to 6 above, the following compounds 
within the scope of the present invention can be prepared. 
EXAMPLE 9 
N-Cyano-N'-(4-cyanophenyl)-N"-cyclohexylguanidine. 
EXAMPLE 10 
N-Cyano-N'-(4-cyanophenyl)-N"-(1-cyclohexylethyl)guanidine. 
EXAMPLE 11 
N-Cyano-N'-(4-cyanophenyl)-N"-(1-phenylethyl)guanidine. 
EXAMPLE 12 
N-Cyano-N'-(4-cyanophenyl)-N"-(phenylmethyl)guanidine. 
EXAMPLE 13 
N-Cyano-N'-[4-(trifluoromethyl)phenyl]-N"-(1,2,2-trimethylpropyl)guanidine. 
EXAMPLE 14 
N-(4-Acetylphenyl)-N'-cyano-N"-(1,2,2-trimethylpropyl)guanidine. 
EXAMPLE 15 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methylamino]benzoic acid, 
ethyl ester. 
EXAMPLE 16 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]-N-methylbenzami 
de. 
EXAMPLE 17 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)amino]methyl]amino]-N-(phenylmethyl 
)benzamide. 
EXAMPLE 18 
4-[[(Cyanoimino)[(1,2,2-trimethylpropyl)aminomethyl]amino]-N,N-dimethylbenz 
amide. 
EXAMPLE 19 
N-Cyano-N'-[4-(1-piperidinylcarbonyl)phenyl]-N"-(1,2,2-trimethylpropyl)guan 
idine. 
EXAMPLE 20 
N-Cyano-N'-[4-(4-morpholinylcarbonyl)phenyl]-N"-(1,2,2-trimethylpropyl)guan 
idine. 
EXAMPLE 21 
N-Cyano-N'-[4-(4-thiomorpholinylcarbonyl)phenyl-N"-(1,2,2-trimethylpropyl)g 
uanidine. 
EXAMPLE 22 
N-Cyano-N'-[4-[[4-(phenylmethyl)-1-piperazinyl]carbonyl]phenyl]-N"-(1,2,2-t 
rimethyl-propyl)guanidine. 
EXAMPLE 23 
N-Cyano-N'-(5,6,7,8-tetrahydro-5-oxo-2-naphthalenyl)-N"-(1,2,2-trimethylpro 
pyl)guanidine. 
EXAMPLE 24 
N-Cyano-N'-(1,1-dimethylethyl)-N"-(1,2,3,4-tetrahydro-2-methyl-1-oxo-6-isoq 
uinolinyl)guanidine. 
EXAMPLE 25 
N-Cyano-N'-(1,1-dimethylpropyl)-N"-[3-(methylsulfonyl)phenyl]guanidine. 
EXAMPLE 26 
N-Cyano-N'-(1,1-dimethylpropyl)-N"-[3-(methylsulfinyl)phenyl]guanidine. 
EXAMPLE 27 
N-(3-Chloro-4-nitrophenyl)-N'-cyano-N"-(1,1-dimethylethyl)guanidine. 
EXAMPLE 28 
N-Cyano-N'-(4-fluoro-3-nitrophenyl)-N"-(1,1-dimethylethyl)guanidine. 
EXAMPLE 29 
N-Cyano-N'-(4-cyano-3-methoxyphenyl)-N"-(1,2,2-trimethylpropyl)guanidine. 
EXAMPLE 30 
N-(3-Chloro-4-cyanophenyl)-N'-cyano-N"-(1,1-dimethylethyl)guanidine. 
EXAMPLE 31 
N-Cyano-N'-(1-cyclohexylethyl)-N"-[2-(trifluoromethyl)phenyl]guanidine. 
EXAMPLE 32 
N-Cyano-N'-(4-cyanophenyl)-N"-(2-cyclohexyl-1-methylethyl)guanidine. 
EXAMPLE 33 
Mongrel dogs of either sex (10-17 kg) were anesthetized with intravenous 
sodium pentobarbital (30 mg/kg) and a catheter was placed into the right 
femoral artery for collection of blood samples. A Millar Mikrotip catheter 
pressure transducer was placed into the left femoral artery and was 
advanced into the aortic arch for the measurement of arterial blood 
pressure. An endotracheal tube was placed into the trachea and the animals 
were artificially respired such that eucapnia was maintained. 
A left thoracotomy was performed at the fifth intercostal space and the 
heart was exposed. The LCX was isolated proximal to its first branch and a 
silk suture was placed around it for later occlusion. In all animals a 
bent 27 gauge needle with an attached catheter was inserted into the LCX 
distal to the occluder for intracoronary (i.c.) infusions of drug. A 
catheter was placed into the left atrial appendage for dye and radioactive 
microsphere injection. 
The animals were allowed to stabilize for 5-10 minutes at which time an 
arterial blood sample was removed anaerobically for measurement of blood 
gases using a Radiometer (ABL3, Copenhagen) blood gas analyzer. Arterial 
blood pressure, heart rate and ECG were measure. All animals were 
subjected to LCX occlusion for 90 minutes. Before occlusion, the animals 
were divided into 3 groups: 1) Animals given pinacidil (0.9 .mu.g/kg/min., 
i.c., n=6) starting 10 minutes before LCX occlusion. 2) Animals given 
cromakalim (0.1 .mu.g/kg/min., i.c., n=6) starting 10 minutes before LCX 
occlusion. 3) Vehicle control animals for groups 1 and 2 (n=9). At 90 
minutes after the initiation of occlusion, the LCX was reperfused. The 
reperfusion was continued for a total of 5 hours at which time the LCX was 
cannulated and perfused at the animals' existing pressure with Ringer's 
lactate for determination of the area at risk. Patent blue violet dye (1 
mg/kg of a 10 mg/ml solution) was injected into the left atrial catheter 
and the heart was quickly excised. 
The atria were trimmed away leaving only the ventricles. The ventricles 
were then cut transversely into 0.5 cm slices. The borders of the area at 
risk (no dye) were delineated and separated and the slices were incubated 
at 37.degree. C. for 30 minutes in a 1% solution of 2,3,5-triphenyl 
tetrazolium chloride in phosphate buffered saline. The ventricular slices 
were then dried and both sides were carefully traced onto clear 
transparencies. The area at risk and the infarcted region were demarcated 
on the transparencies. These tracings were transferred to paper and the 
areas of interest were measured using planimetric techniques. The infarct 
size was expressed as a percent of the left ventricular (LV) area at risk. 
The number of animals which fibrillated during reperfusion were enumerated 
in each group. No animals fibrillated during LCX occlusion. Ectopic beats 
were counted when the P wave was dissociated from the QRS complex. 
Changes in hemodynamic, blood flow, and infarct size variables were 
analyzed using an analysis of variance. Multiple comparisons were done 
using the Newman-Keuls test. For the determination of differences in the 
frequency of animals fibrillating during reperfusion, the Fisher exact 
test was used. All values are expressed as mean.+-.SE. 
As can be seen in Table 1 of FIG. 1, none of the drug treatments had a 
major effect on arterial blood pressure or heart rate. Despite the lack of 
hemodynamic effects, both pinacidil and cromakalim were observed to 
significantly reduce infarct size expressed as a percent of the area at 
risk (FIG. 2). The number of ectopic beats (number/minute) at various 
times during the reperfusion period are also shown on Table 1. At several 
times during the reperfusion, both cromakalim and pinacidil significantly 
reduced the frequency of ectopy. The frequency of reperfusion fibrillation 
in each respective treatment group is shown in Table 2 of FIG. 3. Seventy 
eight percent of vehicle treated animals fibrillated compared with 
seventeen percent in each of the drug treated groups. These differences 
were significant using the Fisher exact test. 
EXAMPLE 34 
(trans)-N"-Cyano-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopy 
ran-4-yl)-N'-phenyl guanidine 
A. N-cyano-N'-phenylthiourea 
To a suspension of monosodium cyanamide (6.4 g, 100 mmol) in absolute 
ethanol (170 mL), phenylisothiocyanate (12.5 mL, 104.5 mmol) was added 
slowly with stirring at room temperature. The reaction was allowed to stir 
at room temperature for 1 hour and then heated at 75.degree. C. for 4 
hours. The reaction was cooled to room temperature and the colorless solid 
was filtered and washed with ethanol to give the title A compound (13.6 
g), m.p. &gt;250.degree. C. 
B. 
(trans)-N"-Cyano-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzop 
yran-4-yl)-N'-phenyl guanidine 
To a solution of the title A compound (1.06 g, 5.96 mmol) and 
(trans)-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbo 
nitrile (prepared according to Evans et al., J. Med. Chem., 1983, 26, 1582 
and J. Med. Chem., 1986, 29, 2194). (1.0 g, 4.59 mmol) in 
dimethylformamide (5 mL) under argon, 
1-(3-dimethylaminopropyl)-2-ethylcarbodiimide hydrochloride (1.17 g, 5.96 
mmol) was added at room temperature. The reaction mixture was stirred at 
room temperature for 2 hours and then partitioned between 1N HCl and ethyl 
acetate. The organic phase was separated and the aqueous phase was 
reextracted with ethyl acetate and the combined organic phase was washed 
with water, aqueous sodium bicarbonate and brine. After drying over 
anhydrous magnesium sulfate, the solvent was evaporated and the colorless 
residue was triturated with ether to yield the title compound (1.3 g), 
m.p. 247.degree.-249.degree. C. (with effervescence). 
Analysis calc'd for C.sub.20 H.sub.19 N.sub.5 O.sub.2 : C, 66.46; H, 5.30; 
N, 19.38; Found: C, 66.09; H, 5.30; N, 19.35. 
EXAMPLE 35 
(3S-trans)-N"-Cyano-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benz 
opyran-4-yl)-N'-phenylguanidine 
A. 
[3S-[3.alpha.,4.beta.(S*)]]-N-(6-Cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl- 
2H-1-benzopyran-4-yl)-.alpha.-hydroxybenzeneacetamide and 
[3R-[3.alpha.,4.beta.(R*)]]-N-(6-Cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl- 
2H-1-benzopyran-4-yl)-.alpha.-hydroxybenzeneacetamide 
To a solution of 
(trans)-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-carbo 
nitrile (prepared according to Evans et al., J. Med. Chem., 1983, 26, 1582 
and J. Med. Chem., 1986, 29, 2194) (1.64 g, 7.5 mmol), R(-)-mandelic acid 
(1.14 g, 7.5 mmol), hydroxybenzotriazole hydrate (1.0 g, 7.5 mmol) in 
dimethylformamide (15 ml) at 0.degree. C. was added 
dicyclohexylcarbodiimide (1.55 g, 7.5 mmol) at room temperature. The 
reaction mixture was allowed to stir at room temperature for 20 hours and 
then cooled in an ice bath. The solid was removed by filtration and the 
filtrate was concentrated in vacuo. The residue was dissolved in 5% 
methanol in chloroform and washed with 1N sodium hydroxide, 1N 
hydrochloric acid, brine followed by drying over anhydrous magnesium 
sulfate. After removing drying agent the solvent was removed in vacuo. The 
residue was crystallized from ethanol to give 
[3S-[3.alpha.,4.beta.(S*)]]-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl- 
2H-1-benzopyran-4-yl)-.alpha.-hydroxybenzeneacetamide (0.85 g) as a white 
solid, m.p. 235.degree.-237.degree. C.: [.alpha..sub.D ].sup.25 
=-94.9.degree. (c=1, MeOH); .sup.1 H NMR (DMSO-d.sub.6) .delta. 8.45 (d, 
J=8.0 Hz, 1 H), 7.5 (m, 4 H), 7.3 (m, 2 H), 7.0 (s, 1 H), 6.88 (d, J=8.0 
Hz, 1 H), 6.2 (s, 1 H), 5.57 (d, J=5.0 Hz, 1 H), 5.0 (s, 1 H), 4.76 (t, 
J=9.0 Hz, 1 H), 3.75 (dd, J=5.0 % 5.0 Hz, 1 H), 1.40 (s, 3 H), 1.15 (s, 3 
H). 
Analysis calc'd for C.sub.20 H.sub.20 N.sub.2 O.sub.4 : C, 68.17; H, 5.72; 
N, 7.95; Found: C, 68.00; H, 5.52; N, 7.95. 
The residual material recovered from the mother liquor was purified by 
flash chromatography on silica gel eluting with hexane-ethyl acetate (3:7) 
and the product was crystallized from dichloromethane-isopropyl ether to 
give 
[3R-[3.alpha.,4.beta.-(R*)]]-N-(6-Cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl 
-2H-1-benzopyran-4-yl)-.alpha.-hydroxybenzeneacetamide as a white solid, 
m.p. 100.degree.-102.degree. C. (foaming): [.alpha..sub.D ].sup.26 
=+25.6.degree. (c=1, MeOH): .sup.1 H NMR (CDCl.sub.3) .delta. 7.4 (m, 5 
H), 7.26 (t, J=1.0 Hz, 1 H), 6.97 (d, J=9.0 Hz, 1 H), 6.83 (d, J=9.0 Hz, 1 
H), 5.16 (s, 1 H), 4.98 (t, J=9.0 Hz, 1 H), 3.8 (d, J=5.0 Hz, 1 H), 3.55 
(dd, J=4.0 and 5.0 Hz, 1 H), 1.45 (s, 3 H), 1.2 (s, 3 H). 
Analysis calc'd for C.sub.20 H.sub.20 N.sub.2 O.sub.4.0.25 H.sub.2 O: C, 
67.30; H, 5.78; N, 7.84; Found: C, 67.17; H, 5.87; N, 7.44. 
B. 
(3S-trans)-4-Amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-ca 
rbonitrile 
To a solution of 
[3S-[3.alpha.,4.beta.(S*)]]-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl- 
2H-1-benzopyran-4-yl)-.alpha.-hydroxybenzeneacetamide, title A compound 
(6.09 g, 17.0 mmol) in dioxane (60 ml) was added a solution of sulfuric 
acid (6.0 g) in water (30 ml) at room temperature and the reaction mixture 
was heated at reflux temperature for 24 hours. It was then concentrated in 
vacuo and the residue was dissolved in ethyl acetate. The organic layer 
was washed with 1N sodium hydroxide followed by water and dried over 
anhydrous magnesium sulfate. The solvent was evaporated to give the title 
B compound as an oil: .sup.1 H NMR (CDCl.sub.3) .delta. 7.74 (s, 1 H), 
7.42 (dd, J=2.0 and 6.0 Hz, 1 H), 6.82 (d, J=8.0 Hz, 1 H), 3.65 (d, J=10.0 
Hz, 1 H), 3.36 (d, J=10.0 Hz, 1 H), 1.53 (s, 3 H), 1.23 (s, 3 H). 
C. 
(3S-trans)-N"-Cyano-N-(6-cyano-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-ben 
zopyran-4-yl)-N'-phenylguanidine 
To a solution of N-cyano-N'-phenylthiourea (2.11 g, 11.9 mmol) and 
(3S-trans)-4-amino-3,4-dihydro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-6-ca 
rbonitrile (2.0 g, 9.1 mmol), title B compound, in dimethylformamide (20 
mL) under argon was added 1-(3-dimethylaminopropyl)-2-ethylcarbodiimide 
hydrochloride (2.23 g, 11.9 mmol) at room temperature. The reaction 
mixture was stirred at room temperature for 2 hours and then partitioned 
between 1N hydrochloric acid and ethyl acetate. The organic phase was 
separated and the aqueous phase was reextracted with ethyl acetate. The 
combined organic extracts were washed with water, sodium bicarbonate and 
brine. After drying over anhydrous magnesium sulfate, the solvent was 
evaporated and the crude product was purified by flash chromatography on 
silica gel eluting with ethyl acetate/hexanes (7:3) to give a colorless 
solid which was triturated with ether to yield the title compound (0.35 
g), m.p. 215.degree.-216.degree. C.: [.alpha.].sub.D.sup.25 -33.5.degree. 
(c=1, MeOH); .sup.1 H NMR (DMSO-d.sub. 6) .delta. 9.28 (s, 1 H), 7.58 (d, 
J=8.0 Hz, 3 H), 7.35 (m, 4 H), 7.15 (m, 1 H), 6.90 (d, J=8.2 Hz, 1 H), 
5.92 (br s, 1 H), 4.92 (t, J=9.0 Hz, 1 H), 3.72 (br d, J=5.9 Hz, 1 H), 
1.4I, 1.18 (s, 3 H each); .sup.13 C NMR (DMSO-d.sub.6) 159.2, 156.3, 
137.5, 132.6, 132.5, 129.0 124.8, 124.7, 123.6, 119.0, 117.8, 117.0, 
102.6, 80.4, 70.9, 51.9, 26.6, 18.6; IR (KBr) 2226, 2179, 1609, 1582, 
1491, 1267 cm.sup.-1. 
Analysis calc'd for C.sub.20 H.sub.19 N.sub.5 O.sub.2.0.24 H.sub.2 O: 
C. 65.26; H, 5.40; N, 19.02; Found: C, 65.62; H, 5.36; N, 18.57. 
HPLC: 99.5% by Chiracel OD column/hexanes (80%), isopropanol (20%), formic 
acid (0.1%).