bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of the Active Sites of the Mesoporous Molecular Sieve MCM-41 and Related Zeolitic Materials by Using Fourier-Transform I.R., Continuous-Wave E.S.R. and Pulsed E.S.R. Spectroscopic Probes
Authors: Lim Yau-Yan , MacLachlan Dugald J. , Smith Thomas D. , Jamis Jim , Pilbrow John R. , Song Ruitian
Published: August 2004

Infrared spectroscopic measurements have been made on hydrocarbons and
hydrogen cyanide adsorbed, separately and competitively, on mesoporous
molecular sieves MCM-41 of all-silica composition and with various
aluminium(III) , titanium(IV) or vanadium(V) contents. Similar i.r.
spectroscopic measurements were made on the porous aluminium phosphates
AlPO4-5 and VPI. Characterization of the cationic
binding sites of MCM-41 has been achieved by comparison of the e.s.r. spectra
of the cationic copper(II) chelate acetylacetonatocopper(II)
tetramethylethylenediamine, adsorbed by MCM-41, and by the sodium ion forms of
zeolite-Y, mordenite, ultrastable and chromatographic grade silica. Both sets
of results show that for mesoporous MCM-41 Brønsted acidity and
possibly cation-exchange sites arise from ill-defined structural defects and
from the silanol groups which are not greatly influenced by the presence of
metal cations within the thick-walled honeycomb structure.
Stable Imido Amido Complexes of Tungsten(VI).
Authors: Nielson Alastair J. , Clark George R. , Rickard Clifton E. F.
Published: August 2004

Reaction of
Me3SiNHC3H3Pri2-2,6
with
[WC13(NC6H3Pri-2,6)]
in thf gives
[WCl3(NC6H3Pri2-

2,6)(NHC6H3Pri2-2,6)(thf)]
(1), and reaction in CH2Cl2 in the
presence of py gives
[WCl3(NC6H3Pr
i2-2,6)(NHC6H3Pri2-2,6)(py)]
(2). Addition of 1 equiv. of
NH2C6H3Pri2-2,6
to
[WCl4(NC6H3Pri2-2,6)]
in CH2Cl2 gives the 1 : 1 adduct
[WCl4(NC6H3Pri2-2,6)(NH2C6H3Pri2-2,6)]
(3) which when reacted with 1 equiv. of
Me3SiNHC6H3Pri2-2,6
gives rise to
[WCl3(NC6H3Pri2-2,6)(NHC6H3Pri2-2,6)(NH2C6H3Pri2-2,6)]
(4) and also the tris amido complex
[WCl3(NHC6H3Pri2-2,6)3]
(5). Complex (4) converts into complex (5), and after long reaction periods
only complex (5) is isolated. Addition of 1 equiv. of
Me3SiNHC6H3Pri2-2,6
to
[WCl5(NC6H3Pri2-2,6)NEt4
in CH2Cl2 gives rise to
[WCl4(NC6H3Pri2-2,6)(NHC6H3Pri2-2,6)]
NEt4 (6), and if
Me3SiNHC6H3Me2-2,6
is used, instead,
[WCl4(NC6H3Pri2-2,6)(NHC6H3Me2-2,6)]
NEt4 (7) results.
Me3SiNHC6H5
gives unidentified mixtures of products. Reaction of
NH2C6H3Pri2-2,6
with [WCl4(O)] leads to the complex
[WCl4(NC6H3Pri2-2,6)(NHC6H3Pri2-2,6)]
NH3C6H3Pri2-2,6
(8) which was characterized by X-ray crystallography. The structure shows an
octahedral array with cis-oriented imido and amido ligands. For the imido
ligand the W-N bond length is 1·67(2) Å and W-N-C bond angle
174(2)°; for the amido ligand, the corresponding values are 1·87(2)
Å and 144(2)°. The amido ligand orientates so that any NH contacts
with nearby chlorine ligands are minimized. Complexes (1)-(8) give insight
into an intramolecular NH proton transfer process leading to an organoimido
ligand.
The Metabolites of Trichoderma longibrachiatum. III. Two New Tetronic Acids: 5-Hydroxyvertinolide and Bislongiquinolide
Authors: Andrade Romano , Ayer William A. , Trifonov Latchezar S.
Published: August 2004

Two new tetronic acid derivatives, 5-hydroxyvertinolide (1) and
bislongiquinolide (2), have been isolated from the fungus
Trichoderma longibrachiatum Rifai aggr., which is
antagonistic to the fungus Mycena citricolor, the
causative agent of the American leaf spot disease of coffee. The structures
were determined by a combination of spectroscopic techniques, including
1H and 13C n.m.r., i.r., u.v.,
c.d., and mass spectrometry.
Synthetic Approaches to the Angucycline Antibiotics: A Synthesis of (±)-Hatomarubigin B and C.
Authors: Caygill Graham B. , Larsen David S. , McFarlane Brett S.
Published: August 2004

The synthesis of the angucycline natural products hatomarubigin B and C in
racemic form is described. The key step in the construction of the
benz[a]anthraquinone skeleton of these
molecules was the Diels–Alder reaction of the acetate of
(E,1R*,5R*)-3-(2′-methoxyvinyl)-5-methylcyclohex-2-en-1-ol
and 5-acetoxy-8-hydroxy-1,4-naphthoquinone. Methylation of the C11 phenolic
group of the resulting cycloadduct, followed by aromatization of the B ring
with subsequent deacylation gave (±)-hatomarubigin C. Oxidation of the
latter compound with Dess-Martin periodinane,
1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one,
gave (±)-hatomarubigin B.
New Isoflavonoids from Root Bark of Kowhai Sophora microphylla)
Authors: Horticultural Graeme B. Russell
Published: August 2004

Two new isoflavanones, phyllanone A (1) and phyllanone B (2), together with
the known isoflavonoids isosophoranone (3), maackiain (4), medicagol (5) and
lupalbigenin (6), have been isolated from the root bark
ofSophora microphylla. The structures and chirality of
the new compounds have been determined from spectroscopic analysis.
Synthesis of New 9,15-Cyclogibberellins from Developing Apple Seeds: Confirmation of Structure for GA105 and GA108
Authors: Pour Milan , Kraft-Klaunzer Petra , Furber Mark , Mander Lewis N. , Twitchin Bruce , Oyama Naomi , Murofushi, Noboru , Yamane Hisakazu , Yamauchi Tadayuki
Published: August 2004

The structures of two new gibberellins (GA105 and
GA108) from developing apple seeds were confirmed as
2β- and 11β-hydroxy-9,15-cyclo-GA9,
respectively, by synthesis of their methyl esters (7) and (8); the analogous
1α-, 2α- and 11α-isomers were also prepared, the last two
being identified as metabolites of 9,15-cyclo-GA9 (2)
formed in feeding experiments with fern prothallia of
Lygodium circinnatum. The route to (7) began with the
Birch reduction of gibberellic acid (GA3) methyl ester
3,13-dimesylate, thereby removing the oxygen substituents from C3 and C13. A
series of iodolactonizations and elimination processes followed by ozonolysis
of the 17-methylene group furnished (19) which, on treatment with potassium
hydride, underwent intramolecular alkylation to afford the cyclogibberellin
(20). Further functional group manipulation then led to (7) via its
2α-epimer (23). The previously prepared 11β-bromocyclogibberellin
(28) was also subjected to a series of functional group manipulations and
deletions to afford the 11α-hydroxy analogue (33), and thence the
11β-epimer (8) by means of an oxidation/reduction cycle;
1α-hydroxycyclo-GA9 methyl ester (26) was
similarly prepared from the methyl ester of the known 1β-epimer (3).
Imidazo[1,2-b]pyridazines. XXII. Syntheses of Some 2-Aryl-3-methoxy-6-(pyridinylmethylthio and pyridinylmethylamino)imidazo[1,2-b]pyridazines and Their Interaction with Central and Mitochondrial (Peripheral-Type) Benzodiazepine Receptors
Authors: Barlin Gordon B. , Davies Les P. , Ireland Stephen J. , Ngu-Schwemlein Maria M. L.
Published: August 2004

2-Aryl-3-methoxy-6-(pyridinylmethylthio and
pyridinylmethylamino)imidazo[1,2-b]pyridazines
have been prepared and examined as ligands for benzodiazepine receptors. Most
were highly effective in displacing
[3H]diazepam from central benzodiazepine
receptors present in rat brain membranes but showed little capacity for its
displacement from mitochondrial (peripheral-type) benzodiazepine receptors
present in rat kidney membranes. For example,
3-methoxy-2-(3′,4′-methylenedioxyphenyl)-6-(pyridin-2′′-ylmethylthio)imidazo[1,2-b]pyridazine
had an IC50 value of 1 · 7 nM for central
receptors but gave only 39% displacement at 1000 nM for mitochondrial
receptors.
Of all the compounds described in this series of papers,
3-methoxy-6-(2′-methoxybenzylamino)-2-(3′′,4′′-methylenedioxyphenyl)imidazo[1,2-b]pyridazine
was the most active in displacing [3H]diazepam
from central receptors (IC50 0·3 nM), and it had
a low affinity for mitochondrial receptors (40% displacement of
[3H]diazepam at 1000 nM).
Some Organoperoxo Complexes of Tin(IV)
Authors: Tarafder M. Tofazzal H. , Yunus Wan M. Z. W. , Silong Sidik
Published: August 2004

Some novel organoperoxo complexes of tin were prepared by the oxidative
addition of dioxygen with Sn 2+. These are the first
reported examples of this kind. The complexes isolated have the compositions
[Sn(O2)2.2L],
[Sn(O2)2L′],
[Sn(O2)L′′2],
[Sn(O2)C5H3N(COO)2H2O]
and
[Sn(O2)2L′′′]
(L = pyridine, pyridine N-oxide,
triphenylphosphine oxide, aniline; L′ = ethylenediamine,
2-aminopyridine, o-phenylenediamine; L′′
= pyridine-2-carboxylato, 2-aminophenolato, quinolin-8-olato,
glycinato; L′′′ = diethylenetriamine and
triethylenetetramine). The complexes were characterized by elemental analysis,
conductivity measurements and infrared spectroscopic studies. None of these
complexes showed oxygen transfer reactions. The
ν1(O-O) stretching frequencies appear at 805-820
cm-1 , and are significantly insensitive to the choice
of the coligands used. Extensive pp-dp bonding in the complexes renders
absolute kinetic stability to the complexes.
The Synthesis of 1,8-Cineoles. The Origin of the Oxygen Atom
Authors: Brecknell Douglas J. , Carman Raymond M. , Garner A. Christopher
Published: August 2004

1,8-Cineoles can be synthesized by ring closure of
p-menthane precursors carrying the potential ether
oxygen atom on either C1 or C8. Comparisons are made between these two routes.
Some Coordination Chemistry of the Bidentate Nitrogen-Donor Ligand 2-(2-Aminophenyl)pyridine
Authors: Thompson Alexander M. W. Cargill , Batten Stuart R. , Jeffery John C. , Rees Leigh H. , Ward Michael D.
Published: August 2004

Complexes of the chelating bidentate nitrogen-donor ligand
2-(2-aminophenyl)pyridine (L) are described.
[PdL2]
[PF6]2 (1) forms two
types of crystal (1a,b) of which (1a) was crystallographically characterized
[space group P
21/c a
10·974(6), b 14·757(4),
c 8·223(2) Å; β 104·66(5)°;
V 1288·3(8) Å3;
Z 2]. It has a square-planar donor set about the
metal, with the ligands mutually trans and with a twist
of 35° between the pyridyl and phenyl rings. 1 H
n.m.r. spectroscopy shows that pure (1a) and (1b) equilibrate in solution; it
is likely that (1b) is thecis form of the complex.
Electrochemical measurements on [Ru(bipy)2L]
[PF6]2 (2) show that the
RuII /RuIIIcouple is
cathodically shifted by 0·34 V with respect to
[Ru(bipy)3]2+ ,
indicating that replacing a pyridyl donor by an amine results in a significant
increase of electron density on the metal centre: this effect is much larger
with a primary amine ligand than with tertiary amines. The e.p.r. spectrum of
[CuL2]
[PF6]2 (3) shows that a
small extent of association into a dinuclear complex occurs, a reaction which
is solvent-dependent: addition of pyridine breaks up the dimer by coordination
to the axial sites of the monomer, whose spectrum is characteristic of a
tetragonal geometry (i.e. a planar array of two ligands L, and axial solvent
molecules). Attempted recrystallization of other complexes of L from acetone
afforded
[C14H15N2]
[PF6] (4), in which the free ligand L has
condensed with acetone and then undergone an intramolecular cyclization by
attack of the pyridyl nitrogen atom on the electrophilic carbon atom of the
imine bond; this compound was also crystallographically characterized
[space group P
21/n; a
8·258(2), b 10·036(4),
c 17·976(7) Å; β 100·12(3)°;
V 1466·8(10) Å3 ;
Z 4]
Synthesis and Substitution Reactions of N-Protected 2-(Phenylselenonylmethyl)pyrrolidines
Authors: Cooper Matthew A. , Ward A . David
Published: August 2004

Alkyl phenyl selenides derived from the benzeneselenenyl chloride induced
cyclization of N-protected pent-4-enylamines can be
converted in good yield into the corresponding 2-hydroxymethyl- or 2-
alkoxymethyl-substituted pyrrolidines by oxidation to the corresponding
selenone, followed by reaction with water (or hydroxide) or with the
corresponding alcohol. Details of the reactions and possible mechanisms for
the substitution are discussed.
β-Acarbose. IV. Model Studies on the Alkylation of Cyclohexylamine with a Carbohydrate Epoxide
Authors: McAuliffe Joseph C. , Skelton Brian W. , Stick Robert V. , White Allan H.
Published: August 2004

1,6:3,4-Dianhydro-2-O-benzyl-β-D-galactose has been
treated with cyclohexylamine to give an amino alcohol, convertible into
2,3-di-O-acetyl-1,6-anhydro-4-cyclohexylamino-4-deoxy-β-D-glucose
by reduction and acetylation. The anhydro bridge of this diacetate has been
successfully opened under acetolysis conditions. The original amino alcohol
has also been converted into a cyclic carbamate, a carbamate and an aziridine,
by utilizing a variety of reagents and conditions. The 1,6-anhydro bridge of
the cyclic carbamate, also containing a 2-O-benzyl
ether, could be opened under acetolysis conditions but a comparable reaction
was best done on the derived 2-O-acetyl compound. The
resulting mixture of D-glucosyl acetates, still containing a cyclic carbamate,
was convered into a methyl β-D-glucoside. The cyclic carbamate could be
removed by hydrolysis with aqueous base to give a model glycoside for a
synthesis of β-acarbose. Single-crystal X-ray structure determinations are
reported for
2,3-di-O-acetyl-4-[acetyl(cyclohexyl)amino]-1,6-anhydro-4-deoxy-β-D-glucose,
1,6-anhydro-2-O-benzyl-3,4-[N-(cyclohexyl)epimino]-3,4-dideoxy-β-D-allose
and methyl
2,6-di-O-acetyl-3,4-O,N-carbonyl-4-cyclohexylamino-4-deoxy-β-D-glucoside.
The Constituents of Marine Sponges. IX New Norditerpenoids from Aplysilla pallida
Authors: Hambley Trevor W. , Taylor Walter C. , Toth Stephen
Published: August 2004

Four novel norditerpenoids were isolated from a new encrusting sponge,
conveniently labelled Aplysilla pallida. The structures
of aplypallidenone (1), aplypallidoxone (2), aplypallidione (3) and
aplypallidioxone (4) were elucidated by spectroscopic studies and the crystal
structures of aplypallidenone and aplypallidoxone have been determined by
X-ray diffraction methods. The structure of (1) was refined to a residual of
0·040 for 1665 independent observed reflections and the structure of
(2) was refined to a residual of 0·031 for 1699 independent observed
reflections. The crystals of (1) are orthorhombic, space group
P212121,
a 7·728(2), b
10·838(4), c 24·880(5) Å,
Z 4. Those of (2) are monoclinic, space group
C 2, a 23·927(7),
b 6·674(2), c
14·033(3) Å, Z 4.
Binding Studies on Modified Vancomycin
Authors: Ang Siau-Gek , Peh Yoke-Keow
Published: August 2004

Binding studies were carried out on a vancomycin derivative to examine its
potential bactericidal activity. Of particular interest was the effect of
dimethylation of the amino group at the N-terminus of vancomycin on the
binding ability of the antibiotic to bacterial cell-wall peptide analogues,
namely Ac-D-Ala-D-Ala and Ac2-L-Lys-D-Ala-D-Ala.
Reductive methylation was carried out with sodium cyanoborohydride and
formaldehyde, and the binding constants of the vancomycin derivative with the
peptides were measured by ultraviolet difference spectroscopy.
Functionalization of 5,15-Diphenylporphyrin: Preparation and X-Ray Crystal Structures of meso Nitro, Bromo, and Trimethylsilylethynyl Derivatives
Authors: Arnold Dennis P. , Bott Raymond C. , Eldridge Helen , Elms Fiona M. , Smith Graham , Zojaji Mike
Published: August 2004

Substitutions on 5,15-diphenylporphyrin led to the isolation of mono- and
di-bromo and mono- and di-nitro derivatives, which were converted into their
respective nickel(II) complexes. Reaction of the bromoporphyrins with
iodine/silver nitrite resulted in nitrodebromination as well as
conventional nitration. The nickel(II) complex of
5-nitro-10,20-diphenylporphyrin was reduced to the 5-amino derivative. The
nickel(II) complexes of the bromoporphyrins were converted into the respective
mono- and bis-(trimethylsilylethynyl) species. The crystal structures of
5-nitro-10,20-diphenylporphyrin, 5-bromo-
10,20-diphenylporphyrinatonickel(II), and
10,20-diphenyl-5-(trimethylsilylethynyl)porphyrinatonickel(II) were
determined.
Potential GABA B Receptor Antagonists. IX The Synthesis of 3-Amino-3-(4-chlorophenyl)propanoic Acid, 2-Amino-2-(4-chlorophenyl)ethylphosphonic Acid and 2-Amino-2-(4-chlorophenyl)ethanesulfonic Acid
Authors: Abbenante Giovanni , Hughes Robert , Prager Rolf H.
Published: August 2004

This paper describes the synthesis of 3-amino-3-(4-chlorophenyl)propanoic acid
and the corresponding phosphonic and sulfonic acids, lower homologues of
baclofen, phaclofen and saclofen respectively. The chlorinated acids were all
weak specific antagonists of GABA at the GABAB receptor,
with the sulfonic acid (pA2 4·0) being stronger
than the phosphonic acid (pA2 3·8) and carboxylic
acid (pA2 3·5).
Studies on Lanthanide Complexes of the Tripodal Ligand Tris(benzimidazol-2-ylmethyl)amine (ntb). Crystal Structures of [Ln(ntb)(NO3)3].H2O (Ln = Ce, Er)
Authors: Su Cheng-Yong , Kang Bei-Sheng , Mu Xiao-Qin , Sun Jie , Tong Ye-Xiang , Chen Zhong-Ning
Published: August 2004

The tripodal ligand tris(benzimidazol-2-ylmethyl)amine (ntb) reacts with
lanthanide nitrates in methanol to give the mononuclear complexes
[Ln(ntb)(NO3)3].H2O
(Ln = La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er) which have been characterized
by elemental analyses, infrared, electronic and 1H
n.m.r. spectroscopies, X-ray diffraction patterns, and conductivity
measurements. The crystal and molecular structures of two complexes
[Ln(ntb)(NO3)3].H2O
(Ln = Ce, Er) have been determined. The cerium complex crystallizes in
the monoclinic system, space group
C2/c with
a 26·79(1), b
14·497(8), c 17·20(1) Å, β
99·06(4)°, V 6596(6)
Å3 , Z 8, while the erbium
complex crystallizes in the cubic system, space group
Pa-3 with a
18·2504(1) Å, V 6078·79(6)
Å3, Z 8. In both cases the
central metal ions are coordinated to the four nitrogen atoms of ntb and six
oxygen atoms of three chelating nitrate groups. The total coordination number
of the metal ion is 10. Spectroscopic analyses suggest that other complexes
show a similar coordination mode. The fluorescence properties of the
samarium(III), europium(III), terbium(III), and dysprosium(III) complexes were
investigated.
Potential GABAB Receptor Antagonists. X The Synthesis of Further Analogues of Baclofen, Phaclofen and Saclofen
Authors: Prager Rolf H. , Schafer Karl
Published: August 2004

In an attempt to obtain new compounds with binding activity at the
GABAB receptor site, we report the synthesis of
3-amino-2-arylpropanoic acids, and the sulfonic, phosphonic and hydroxamic
acid analogues. In addition, we report the synthesis of the isomer of
phaclofen, 3-amino-1-(4-chlorophenyl)-propylphosphonic acid, and the higher
homologue of baclofen, 5-amino-2-(4-chlorophenyl)pentanoic acid.
Synthetic, Structural and Vibrational Spectroscopic Studies in Bismuth(III) Halide/N,N ′-Aromatic Bidentate Base Systems. III Some Novel Bismuth(III) Halide/N,N ′-Bidentate Ligand (1 : 1)
Authors: Bowmaker Graham A. , Junk Peter C. , Lee Aaron M. , Skelton Brian W. , White Allan H.
Published: August 2004

Syntheses and single-crystal room-temperature X-ray structure determinations
are recorded for a number of adducts obtained by the crystallization of
bismuth(III) halides with 2,2′-bipyridine (bpy) or 1,10- phenanthroline
(phen) from dimethyl sulfoxide (dmso) solution.
[(phen)BiX3(O-dmso)2].dmso,
X = Cl, Br, are triclinic,
P-1,a ≈
14·6, b ≈ 9·7, c
≈ 9·5 Å, α ≈ 96, β ≈ 96, γ ≈ 98°,
Z = 2; conventional R on
| F| were 0·057, 0·037 for
No 5775, 4847 independent
‘observed’ (I >
3σ(I)) reflections respectively. The metal atom
coordination environments are seven-coordinate pentagonal bipyramidal with
axial halides and the two O-dmso ligands
cis in the equatorial plane.
BiI3/phen/dmso (1 : 1 : 1 ) is orthorhombic,
Pmc21, a
12·745(3), b 9·697(3),
c 18·335(5) Å, Z
= 4, R 0·049 for
No 2012. The complex is ionic
[(phen)BiI2(O-dmso)3]+[(phen)BiI4]-,
the halide atoms being axial in a pentagonal bipyramidal array about the metal
in the cation, with a quasi-octahedral coordination environment in the anion.
With bpy, by contrast, BiI3/bpy/dmso (1 : 1 : 1)
is obtained, orthorhombic, Pnma, a
17·86(2), b 12·87(1),
c 8·47(1) Å, Z
= 4, R 0·058 for
No 1194, a neutral mononuclear
complex
[(bpy)BiI3(O-dmso)] with
a six-coordinate array about the metal, O-dmso
trans to an iodine atom. Bands in the far-infrared and
Raman spectra due to the vibrations of the
O2N2BiX3
cores in
[(phen)BiX3(O-dmso)2]
(X = Cl, Br) are assigned, and discussed in relation to the structures
of the complexes.
Structural Systematics of Metal Acetylide Complexes: X-Ray Studies of Some 'Extended-Chain' Gold σ-Acetylide Complexes
Authors: Whittall Ian R. , Humphrey Mark G. , Hockless David C. R.
Published: August 2004

The structures of
Au(4-C≡CC6H4XYC6H4-4′-NO2)(PPh3)
(XY = (E )-CH=CH
(1), (Z)-CH=CH (2), C≡C (3), N=CH
(4)) have been determined by single-crystal X-ray diffraction analyses,
refining by full-matrix least-squares analysis. For (1), crystals are
triclinic, space group P-1, with
a8·847(1), b
17·870(4), c 19·705(3) Å,
α116·25(1), β 93·33(1), γ 92·64(2)˚,
Z 4, 6747 unique reflections (703 parameters),
converging at R 0·025 and
Rw 0·029. For (2), crystals
are monoclinic, space group P
21/a, with
a 10·718(6), b
19·398(5), c14·469(3) Å, β
108·96(2)˚, Z 4, 3295 unique reflections
(352 parameters), converging atR 0·040 and
Rw 0·034. For (3), crystals
are triclinic, space group P-1,
with a 10·671(4), b
17·599(7), c 18·220(8) Å, α
116·31(3), β 105·00(4), γ 95·08(4)˚,
Z 4, 4828 unique reflections (703 parameters),
converging at R 0·043 and
Rw 0·030. For (4), crystals
are triclinic, space group P-1,
with a 8·8314(6), b
17·834(2), c 20·001(2) Å, α
115·249(7), β 90·930(7), γ 94·082(7)˚,
Z 4, 4724 unique reflections (703 parameters),
converging at R 0·035 and
Rw 0·034. Despite the
[ligated metal donor]-bridge-[nitro acceptor] composition
of these complexes, Au–C and C≡C distances are normal and
consistent with minimal allenylidene contribution to the ground-state
geometry. Within the 3σ confidence limits, the structural data do not
provide evidence for π*-back-bonding in these complexes
An Unusual Combination of Peptides from the Skin Glands of Ewing's Tree Frog, Litoria ewingi. Sequence Determination and Antimicrobial Activity
Authors: Steinborner Simon T. , Bowie John H. , Tyler Michael J. , Wallace John C.
Published: August 2004

The dorsal glandular skin extract of the brown tree frog
Litoria ewingi contains six major peptides. The amino
acid sequences of the peptides were determined by using a combination of mass
spectrometry and automated Edman sequencing. One of the peptides, caerin 1.1
[Gly Leu Leu Ser Val Leu Gly Ser Val Ala Lys His Val Leu Pro His Val Val
Pro Val Ile Ala Glu His Leu (NH2)], has been
isolated previously from Australian tree frogs of the genus
Litoria, and is a wide-spectrum antimicrobial agent. The
roles of the other five peptides in the amphibian skin have not, as yet, been
determined. The most abundant peptide, uperin 7.1 [Gly Trp Phe Asp Val
Val Lys His Ile Ala Ser Ala Val (NH2)], shows
structural similarity to the uperin group of antimicrobial peptides isolated
from toadlets of the genus Uperoleia (except that uperin
7.1 lacks the final four amino acid residues of uperins from the genus
Uperoleia). The significance of this finding hinges upon
the distant evolutionary relationship of Litoria and
Uperoleia. If the structural similarity implies a single
evolutionary origin, it also implies a conservation of structural origin for
at least 100 million years. Evolutionary convergence is a more likely
explanation for the structural similarity of the peptides from the two genera.
A related peptide, uperin 7.1.1, lacks the first two amino acid residues from
the N-terminal end of uperin 7.1. Uperin 7.1 exhibits minor antimicrobial
activity while uperin 7.1.1. is inactive. The three other peptides are
caeridin 7.1 [Gly Leu Leu Asp Met Val Thr Gly Leu Leu Gly Asn Leu
(NH2)] and two modified peptides of the
tryptophyllin group which we have named tryptophyllin 6.1 [Leu Phe Phe
Trp Gly (NH2)] and 7.1 [Ile Phe Phe Phe Pro
(NH2)]. Tryptophyllins 6.1 and 7.1 are related to
similar peptides isolated from the Australian red tree frog
Litoria rubella: such peptides may be neurotransmitters
or neuromodulators.
Stereoselective Oxidation of Alkyl Azaheterocyclic Sulfides
Authors: Baker, Robert W. , Thomas, George K. , Rea Simon O. , Sargent Melvyn V.
Published: August 2004

The asymmetric oxidation of prochiral sulfides in the presence of
(4R,5R)-2,2-dimethyl-α,α,α′
,α′-tetraphenyl-1,3-dioxolan-4,5-dimethanol (1) has been
investigated. The best results were obtained with 1-t-butylthioisoquinoline
(4) as substrate and reasons for this observation are advanced. Circular
dichroism spectroscopy allowed the absolute configurations of a number of
alkyl azaheterocyclic sulfoxides to be proposed.
Molecular Cocrystals of Carboxylic Acids. XXVI Adducts of the Amino-Substituted Benzoic Acids with Nitroaromatic Lewis Bases: the Influence of Associative Polyfunctional Substituents on Self-Assembly of Molecules in Cocrystallization Processes
Authors: Lynch Daniel E. , Smith Graham , Byriel Karl A. , Kennard Colin H. L.
Published: August 2004

A series of molecular adducts of the isomeric aminobenzoic acids with the
nitro-substituted Lewis bases 2-chloro-5-nitropyridine, 5-nitroquinoline and
5-nitroisoquinoline has been prepared and characterized by using infrared
spectroscopy and X-ray powder diffraction, and in four cases by single-crystal
X-ray diffraction methods. These four compounds are the adducts of
3-aminobenzoic acid with 5-nitroquinoline
[(C7H7NO2)(C9H6N2O2)],
4-aminobenzoic acid with 5-nitroquinoline
[(C7H7NO2)2(C9H6N2O2)],
2-aminobenzoic acid with 5-nitroisoquinoline
[(C7H7NO2)(C9H6N2O2)]
and 4-aminobenzoic acid with 5-nitroisoquinoline
[(C7H7N2O2)(C9H6N2O2)].
Other compounds described are the (1 : 1) adducts of 4-aminobenzoic acid with
2-chloro-5-nitropyridine, and 2-aminobenzoic acid with 5-nitroquinoline. All
adducts involve hydrogen-bonding network associations while in none of the
examples is any proton transfer involved.
Enantiomerization of Pendant-Arm Triaza Macrocyclic Lithium(I) and Sodium(I) Complex Ions
Authors: Whitbread Sonya L. , Weeks Jennifer M. , Valente Peter , Buntine Mark A. , Lincoln Stephen F. , Wainwright Kevin P.
Published: August 2004

The first reported enantiomerization of six-coordinate alkali metal complex
ions, represented by
1,4,7-tris(2-hydroxyethyl)-1,4,7-triazacyclononanelithium(I) and its sodium(I)
analogue in methanol, has been characterized by variable-temperature
13C{1H} n.m.r.
spectroscopy. The respective kinetic parameters are: k
= (1·11 ± 0·05) × 106
and (2·27 ± 0·09) × 105
s-1 at 298·2 K,
ΔH = 27·2
± 0·3 and 21·7±0·2 kJ
mol-1, and
ΔS =
–36·3 ± 1·3 and
–69·6±1·2 J K-1
mol-1. Molecular orbital calculations show that these
enantiomers have distorted trigonal prismatic structures consistent with the
interpretation of the n.m.r. spectra. For the Li+, Na+,
K+, Rb+ and
Cs+ complex ions
log(K/dm3
mol−1) = 3·13±0·09,
3·52±0·05, 3·23±0·05,
2·78±0·10 and 2·47±0·08,
respectively, at 298·2 K and I =
0·05 mol dm-3 (NEt4
ClO4) in methanol, where K is the
complex ion stability constant.
Terpene Metabolites from the Tropical Marine Sponge Axinyssa sp. nov.
Authors: Simpson, Jamie S. , Garson, Mary J. , Hooper, John N. A. , Cline Edith I. , Angerhofer Cindy K.
Published: August 2004

A new sesquiterpene isothiocyanate, ( – )-9-isothiocyanatopupukeanane
(4), has been isolated along with the known sesquiterpene metabolites (
– )-9-isocyanopupukeanane (1), ( – )-2-thiocyanatoneopupukeanane
(2) and ( – )-epipolasin-A (3) from the sponge
Axinyssa sp. nov. Metabolites (1), (2) and (4) showed
modest in vitro antimalarial activity.
Donor Atom Set and Spin State of Iron(II). Bis(ligand)iron(II) and Bis(ligand)nickel(II) Complexes of 2,2′-Bipyridine-6-carbothioamide and 2,2′-Bipyridine-6-carboxamide
Authors: Childs Bradley J. , Cadogan John M. , Craig Donald C. , Scudder Marcia L. , Goodwin Harold A.
Published: August 2004

2,2′-Bipyridine-6-carbothioamide (bpytm) and
2,2′-bipyridine-6-carboxamide (bpyam) are NNS and NNO donors,
respectively, in their cationic bis(ligand)iron(II) and bis(ligand)nickel(II)
complexes. The former ligand provides the stronger field and salts of
[Fe(bpytm)2]2+ have a
singlet ground state, while those of
[Fe(bpyam)2]2+ have a
quintet ground state. The magnetism and the electronic and Mössbauer
spectra of salts of these cations have been measured. The low-temperature
Mössbauer spectra of iron(II) complex salts of the carboxamide indicate,
for the perchlorate and triflate salts, but not for the fluoroborate salt, a
partial transition to singlet-state species. The mode of coordination of the
ligands is indicated by infrared spectral data and has been confirmed by
determination of the structures of
[Ni(bpytm)2]
Cl2.4H2O,
[Ni(bpyam)2]
[BF4]2.H2O
and [Fe(bpyam)2]
[BF4]2. In addition, the
structures of the free ligands have been determined. Hydrogen bonding is
present in the free ligands and their complexes.
2,2′-Bipyridine-6-carbothioamide: monoclinic, space group
P21/c,
a 8·265(3), b
11·175(2), c 11·114(4) Å, β
94·47(2)°, Z 4.
2,2′-Bipyridine-6-carboxamide: monoclinic, space group
P21/c,
a 13·581(2), b
9·926(1), c 16·824(3) Å, β
116·481(7)°, Z 8.
[Ni(bpytm)2]
Cl2.4H2O: triclinic, space group
P-1, a
9·291(5), b 12·426(7),
c 13·425(7) Å, α 113·54(3),
β 95·63(3), γ 94·43(3)°, Z 2.
[Ni(bpyam)2][BF4]2.H2O:
triclinic, space group P-1,
a 10·663(5), b
10·861(6), c 12·799(6) Å, α
68·70(4), β 77·84(4), γ 78·47(4)°,
Z 2. [Fe(bpyam)2]
[BF4]2: orthorhombic,
space group P bcn, a
12¡317(6), B 12¡609(4),
c 16·644(8) Å, Z 4.
Diastereoselective 1,3-Dipolar Cycloadditions and Michael Reactions of Azomethine Ylides to (2R)-3-Benzoyl-4-methylidene-2-phenyloxazolidin-5-one and (2S)-3-Benzoyl-2-t-butyl-4-methylideneoxazolidin-5-one
Authors: Pyne Stephen G. , Safaei-G. Javad , Schafer Karl , Javidan Abdollah , Skelton Brian W. , White Allan H.
Published: August 2004

The 1,3-dipolar cycloaddition reactions of (1) and (11) with the azomethine
ylides derived from N-benzylidene α-amino acid
esters (2) proceed with good to high
exo-diastereoselectivity giving the cycloadducts (4) and
(12), respectively. The cycloaddition adducts can be converted to highly
functionalised prolines (14), (15) and (17) in high enantiomeric purities. The
Michael addition adducts of (1) and (11) with the azomethine ylides derived
from the N-(disubstituted methylidene) α-amino
acid esters (18), (19) and (33) allow for a practical synthesis of all four
stereoisomers of 4-benzamidopyroglutamate. The stereochemistry of these
cycloaddition and Michael adducts has been extensively determined by
single-crystal X-ray structural analysis [compounds (4b), (5b,d),
(12b,d), (13e), (15), (20), (21) and (27)]. Lithium-chelated transition
state structures have been proposed to rationalize the stereochemical outcomes
of these reactions.
Synthesis, X-Ray Crystal Structure and Reactivity of [(tmeda)(p-tolyl)Pd(μ2-I)AgL], an Unusual Silver Iodide Complex; Reversible CO Insertion into the Pd-C Bond of [Pd(PPh3)(p-tolyl)L] (L - = [(C5H5)Co{P(OR)2O}3] - , R = Me, Pri)
Authors: Glaum Marcus , Kläaui Wolfgang , Skelton Brian W. , White Allan H.
Published: August 2004

The palladium complexes
[Pd(PPh3)(aryl)LOR]
(aryl = Ph, p-tolyl;
LOR¯ =
[(C5H5)Co{P(OR)2O}3]¯,
R = Me, Pri) have been prepared by reaction of
[PdI(aryl)(tmeda)] (tmeda =
N,N,N′,N′-tetramethyl-ethylenediamine)
with the silver salts AgLOR in the presence of
PPh3. The complexes
[Pd(PPh3)(aryl)LOR]
rapidly and reversibly insert carbon monoxide to yield the aroyl palladium
complexes [Pd(PPh3)(C(O)-
p-tolyl)LOR] (R = Me,
Pri ). The palladium iodide complex
[PdI(p-tolyl)(tmeda)] and the silver salt
AgLOR in the absence of PPh3 form
an unusual adduct
[(p-tolyl)(tmeda)Pd(µ2-I)AgLOMe]
that contains a short silver-iodide bond (Ag-I 2 · 703(1) Å). The
silver-palladium bond is bridged by iodine (Pd-Ag 3 · 011(1), Pd{I
2 · 5934(9) Å) and the silver atom is coordinated by the
tris-chelating oxygen ligand LOMe.
Crystal and Molecular Structures of t-Butyl Isocyanide-Undecacarbonyl-Tetrahydrido-Tetraruthenium, Ru4(µ-H)4(CO)11(CNBu t )
Authors: Bruce Michael I. , Schulz Michael , Tiekink Edward R. T.
Published: August 2004

The crystal and molecular structures of
Ru4(µ-H)4(CO)11(CNBut)
(2), obtained with Ru4(µ-
H)4(CO)10(CNBut)2
by hydrogenation of
Ru5(µ5-CNBut)(CO)14(CNBut)
(1), have been determined. Crystals of (2) are monoclinic, space group
P 21/c, with
a 12·349(1), b
11·627(3), c 17·0222(7) Å, β
105·785(4)°, V 2351·9(6)
Å3 and Z 4. The structure
was solved by direct methods and refined using 4478 reflections to final
R
0·028(Rw0·033).
An improved procedure for the preparation of (1) in 35–40% yields
is also described.
Alkylation and Conformational Restriction in Calix[6]arene Derivatives: the Synthesis and Structure of 1,2,4,5-Tetrakis(ethoxycarbonylmethyl)-p-t-butylcalix[6]arene Benzene Disolvate
Authors: Harrowfield Jack M. , Mocerino Mauro , Skelton Brian W. , White Allan H.
Published: August 2004

Alkylation of p-t-butylcalix[6]arene with
ethyl bromoacetate results in a mixture of product ethers from which a
tetraether can most easily be isolated in moderate yield; this product
exhibited a degree and pattern of substitution which were unexpected given the
literature on reactions of this type. A room-temperature, single-crystal X-ray
study shows the tetraether compound to be triclinic
P-1, a
16·375(5), b 14·296(9),
c 10·29(2) Å, α 72·4(1), β
87·12(9), γ 72·22(4)°, Z =
1; conventional R on
|F| was 0·095 for 2858 independent
'observed' reflections. The molecule is disposed about a
crystallographic inversion centre and adopts a 1,2,3-alternate conformation
distorted by different ethoxycarbonylmethyl substituent dispositions within
the inversion-related halves. The benzene molecules occupy lattice sites
between the calixarene molecules and are well removed from inclusion in the
calixarene cavity, which is largely blocked by two of the ethoxycarbonylmethyl
substituents.
Structural Systematics of 2/4-Nitrophenoxide Complexes of Closed-Shell Metal Ions. I 2-Nitrophenoxides of Group 1
Authors: Harrowfield Jack M. , Sharma Raj Pal , Shand Todd M. , Skelton Brian W. , White Allan H.
Published: August 2004

Room-temperature, single-crystal X-ray studies are recorded for the variously
hydrated Group 1 metal derivatives of 2-nitrophenol (2-npH =
C6H5NO3). A
provisional determination is reported for
Li(2-np).½H2O, set as monoclinic,
P21/c, a
3·535(3), b 15·06(1),
c 24·42(2) Å, β 91·7(1)°,
Z = 8, conventional R on
F currently 0·18 for
No 875 ‘observed’
(I > 3σ(I)) reflections.
Na(2-np).H2O is monoclinic,
C2/c, a
34 ·23(2), b 3·624(4),
c 35·48(2) Å, β 91·24(4)°,
Z = 24, R 0·060 for
No 1371. Rb(2-np).½
H2O is monoclinic,
C2/c (isomorphous with the
previously determined potassium analogue), a
25·269(9), b 5·381(5),
c 12·010(3) Å, β 105·35(3)°,
Z = 8, R 0·046 for
No 1380.
Cs(2-np).½H2O is monoclinic,
P21/n, a
7·648(3), b 26·19(1),
c 8·713(6) Å, β 111·75(2)°,
Z = 8, R 0·061 for
No 2347. All compounds except the
lithium derivative are two-dimensional polymeric sheets in which the aromatic
rings project to either side of a core of metal atoms coordinated by a web of
2-nitrophenoxide oxygen atoms in various bridging functionalities. The lithium
compound is a novel ‘stair’ polymer with two crystallographically
independent lithium atoms at successive independent Li–O crossbars, the
oxygen atoms of which are phenoxide-Oof each of the two
independent ligands. The lithium atoms are alternately four- and
five-coordinate, the fourth coordination site of the first being occupied by
the water molecule oxygen atom, while the fourth and fifth sites of the second
are occupied by the cis-2-nitro oxygen atoms of the two
ligands
Asymmetric Synthesis of Protected 2-Substituted Cyclopropane Amino Acids
Authors: Pyne Stephen G. , Schafer Karl , Skelton Brian W. , White Allan H.
Published: August 2004

The cyclopropanation reactions of (1a) with ethyl and t-butyl
(dimethylsulfuranylidene)acetate proceeded with good diastereoselectivity and
resulted in the formation of three diastereoisomeric products. The major
diastereoisomeric product ((2a) and (2b), respectively) could be isolated in
pure form by simple recrystallization. The stereochemistry of the major
cyclopropane product (2b) has been determined by single-crystal X-ray
structural analysis. These cyclopropanation products were susceptible to ring
opening of the cyclopropane ring upon reduction with sodium borohydride or
acid hydrolysis. The reaction of (1b) with ethyl
(dimethylsulfuranylidene)acetate gave a mixture of four diastereoisomeric
cyclopropanation products. The reactions of (1a) and (1b) with the sulfur
ylide derived from 3-methoxycarbonylallyldimethylsulfonium bromide were less
successful in terms of product diastereoselectivities.
Electrochemical Synthesis of Optically Active Polyanilines
Authors: Majidi Mir Reza , Kane-Maguire Leon A. P. , Wallace Gordon G.
Published: August 2004

The synthesis of optically active polyaniline salt films of the type PAn.HCSA
(HCSA = camphor-10-sulfonic acid) has been achieved via the
enantioselective electropolymerization of aniline on indium-tin-oxide
(ITO)-coated glass electrodes in the presence of (+)- or (–)-HCSA.
Similar results were obtained under potentiostatic, galvanostatic and
potentiodynamic conditions. The chiroptical and electrical properties of these
novel materials have been characterized by u.v.–visible and circular
dichroism (c.d.) spectroscopy, electrochemical quartz crystal microbalance
techniques and resistometry. The intensity of the c.d. spectra of
potentiostatically grown PAn.(+)-HCSA films was found to increase with
increasing applied potential over the range 0·8–1·1 V
(v. Ag/AgCl) and with increasing charge consumed.
C.d. spectroscopic studies also showed that the polyaniline chains retained
their initial configuration when the (+)-HCSA dopant acid in
PAn.(+)-HCSA films was replaced by HCl via potential cycling in 1 mol
dm-3 HCl. Similarly, chemical de-doping of
PAn.(+)-HCSA with 0·5 mol dm-3
NH4OH produced optically active emeraldine base, which
upon re-doping with HCl gave optically active PAn.HCl with a c.d. spectrum
very similar to that of the original PAn.(+)-HCSA. These results suggest
that chiral holes may be formed in the polymer matrix during both redox and
chemical de-doping/re-doping cycles with PAn.(+)-HCSA salt films.
Total Synthesis of (±)-Iso-trans-trikentrin B
Authors: MacLeod John K. , Ward Annemarie , Willis Anthony C.
Published: August 2004

The synthesis of the title compound, a member of a family of
cyclopent[g]indoles isolated from a marine
sponge, is described. Most of the synthetic sequence was developed starting
from the more readily available cis-1,3-dimethylindan.
An X-ray crystal structure of the indanol (24), the precursor of
trans-1,3-dimethylindan, confirmed its relative
stereochemistry.
Neutron Powder Diffraction Study of Lead Hydroxyapatite
Authors: Kim, Jean Y. , Hunter, Brett A. , Fenton Ronald R. , Kennedy Brendan J.
Published: August 2004

Neutron powder diffraction data, collected both at room temperature and at 10
K, for
Pb10(PO4)6(OH)2,
have been used to refine structural parameters by the Rietveld method. The
compound is hexagonal at both temperatures, P
63/m; Z
= 1, a = 9·8828(4);
9·8355(3) and c= 7·4406(2);
7·4100(1) Å at 295 and 10 K, respectively. The results show the
displacement of the hydroxide group from the Pb(2) triangle is greater than
that expected from steric arguments alone.
Organolanthanoids. XXI Synthesis of Bis- and Tris-(diphenylphosphinocyclopenta- dienyl)lanthanoid Compounds and the X-Ray Crystal Structures of [Ln(C5H4PPh2)3(OPPh3)]·(thf)1
Authors: Deacon Glen B. , Forsyth Craig M. , Gatehouse Bryan M. , Philosof Anna , Skelton Brian W. , White Allan H. , White Paul A.
Published: August 2004

Redox transmetallation ofTl(C5H4PPh2)with an excess of Sm in refluxing thf (thf = tetrahydrofuran) or Eu indme (dme = 1,2-dimethoxyethane) at room temperature gave thelanthanoid(II) compounds[Sm(C5H4PPh2)2](1) and[Eu(C5H4PPh2)2(dme)](2). Crystallization of (1) or[Yb(C5H4PPh2)2(dme)]with OPPh3 in dme yielded[Sm(C5H4PPh2)2(OPPh3)2](3) and[Yb(C5H4PPh2)2(OPPh3)2](4). Room-temperature transmetallation ofTl(C5H4PPh2)with Nd gave the lanthanoid(III) compound[Nd(C5H4PPh2)3(thf)](5), but analogous reactions with La, Pr, Er, Gd and Y in refluxing thfgenerally gave intractable oils, although in one instance impure[La(C5H4PPh2)3(thf)]·(thf)0 · 5,namely(6)·(thf)0 · 5, wasisolated. This complex was also obtained at room temperature by usingLaI3-activated La metal. Oxidation of (1) with 1 equiv.ofTl(C5H4PPh2)in toluene yielded solvent-freeSm(C5H4PPh2)3(7). Addition of OPPh3 to these systems allowed theisolation of[Ln(C5H4PPh2)3(OPPh3)]·(thf)x(x = 0-1 · 5; Ln = La (8), Pr (9),Nd (10), Sm (11), Er (12), Y (13)). Single-crystal X-ray structuredetermination of(10)·(thf)1 · 5,(11)·(thf)1 · 5 and(12)·(thf)1 · 5revealed formally 10-coordinate complexes with an O-bondedOPPh3, threeη5-C5H4PPh2ligands and lattice thf. The centroids of the C5 ringsand the oxygen atom surround the central metal in a distorted tetrahedralarray.
The Correlation of Carbohydrate Molecular Motion with N.O.E. Buildup Spectra.
Authors: Coxon Edward E. , Coxon James M. , Boswell D. Ross
Published: August 2004

The rates of buildup of the n.O.e. (nuclear Overhauser effect) including the
effects of conformational averaging, anisotropic tumbling and internal motion
were calculated for methyl
O-α-L-fucopyranosyl-(1→2)-β-D-galactopyranoside.
This methodology is found to effectively distinguish between different
computational models of carbohydrate solution behaviour, providing a new tool
for the evaluation of molecular modelling predictions in solution. These
studies support the MM2* force field, continuum
solvent treatment (GB/SA) and molecular dynamic (MD) integration, and
reinforce the concept of flexibility about the glycosidic linkage.
The Synthesis, Separation and Structures of Three [Co(cyclen)((S)-AlaO)]2+ Isomers. The Alkaline Hydrolysis of [Co(cyclen)((S)-AlaO)]2+
Authors: Buckingham David A. , Buckingham David A. , Clark Charles R. , Clark Charles R. , Rogers Andrew J. , Rogers Andrew J. , Simpson Jim , Simpson Jim
Published: August 2004

The reaction of
[Co(cyclen)(OH2)OH]2+
(cyclen = 1,4,7,10-tetraazacyclododecane) with
(S)-alanine at pH 7·2 gives a mixture of three
[Co(cyclen)((S)-AlaO)]2+
isomers (1)–(3). These have been isolated by using both cation
ion-exchange chromatography (Dowex 50 W×2, HCl eluent) and reversed
phase ion-pair chromatography (C18,
p-toluenephosphate in MeOH/H2O
eluent). By using a combination of 1H n.m.r. techniques
(n.O.e. and COSY) for solutions in
(CD3)2SO the
syn(N),anti(O) (1),
syn(O), anti(N) (2) and
syn(N), syn(O) (3) configurations
have been assigned to these isomers. These have been confirmed by
single-crystal X-ray analysis:
[Co(cyclen)((S)-AlaO)]
I2.H2O, isomer (1),
P43212, a
= b = 8·55150(10),
c 51·8693(11) Å, Z 8,
R 0·0343;
[Co(cyclen)((S)-AlaO)]
(ClO4)2.H2O,
isomer (2),
P212121,
a 8·499(3), b
14·538(5), c 16·592(4) Å,
Z 4, R 0·0388;
[Co(cyclen)((S/R)-AlaO)]
ZnBr4, a 1 : 1 mixture containing both
(S)-alanine (isomer (3)) and
(R)-alanine,
P21/c,
a 7·618(2), b
13·806(4), c 19·094(7) Å,
Z 4, R 0·0726. In alkaline
solution (0·1–1·0 M NaOH, 25·0°C,
I = 1·0 M (NaClO4)),
equilibration between (1), (2) and (3) is faster than hydrolysis to give
cis-[Co(cyclen)(OH)2]++(S)-AlaO-.
Time zero spectroscopic observation (300 nm) allowed the equilibrium constant,
K, for the reaction
[Co(cyclen)((S)-AlaO)]2+
+ OH- ↔ [Co(cyclen –
H)((S)-AlaO)]+
+H2O to be determined as 1·05
M-1 at 25·0°C and I
= 1·0 M. The hydrolysis reaction follows the rate law
kobs =
kKK1K2[OH-]2/(1+K[OH-]+KK1K2[OH-]2)
with k = 1·0 s-1
corresponding to rate-determining loss of
(S)-AlaO- from the ring-opened
complex, [Co(cyclen – H)((S)-AlaO)OH].
The Synthesis of (S)-3-Acetylthio-2-benzylpropionic Acid from (Z)-2-Chloromethyl-3-phenylprop-2-enoic Acid by Asymmetric Hydrogenation: a Chiral Building Block of an Enkephalinase Inhibitor
Authors: Yuasa Yoko , Yuasa Yoshifumi , Tsuruta Haruki
Published: August 2004

(S)-2-Benzyl-3-chloropropionic acid (7) was synthesized
from (Z)-2-(chloromethyl)-3-phenylprop-2-enoic acid (5)
by asymmetric hydrogenation with a ruthenium
2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl
complex in the presence of triethylamine. Acetylthiolation then gave
3-acetylthio-2-benzylpropionic acid (2), a subunit of the enkephalinase
inhibitor thiorphan (1).
The Synthesis of Novel Hybrid Monomers
Authors: Chan Grace Y. N. , Solomon David H. , Looney Mark G. , Veluayitham Sheela
Published: August 2004

Novel hybrid amide–ester crosslinking monomers were prepared by using
methodology which utilizes the differential functionalities present within a
convenient amino alcohol. Modification of the procedure to a simple one-pot
reaction enables the generation of these unique monomers to be scaled to
commercial levels.
Dipolar Cycloaddition Reactions of Nitrilimines
Authors: Dunstan James B. F. , Elsey Gordon M. , Russell Richard A. , Savage G. Paul , Simpson Gregory W. , Tiekink Edward R. T.
Published: August 2004

A series of γ-substituted α-methylidene-γ-butyrolactone
derivatives underwent regiospecific 1,3-dipolar cycloaddition with
N-methyl-C-phenylnitrilimine.
These reactions proceeded regiospecifically and with high
diastereoselectivity, generally favouring the anti
diastereomer as determined by n.m.r. spectroscopy and semiempirical molecular
orbital calculations. The assignment for one product was confirmed by X-ray
crystallography.
N-Methyl-C-phenylnitrilimine
underwent regiospecific cycloaddition with a range of C=S-containing
dipolarophiles. Substituted thioureas were generally unreactive as
dipolarophiles, while 5-thio-substituted
1,3,4-thiadiazole-2(3H)-thiones underwent ready reaction
to produce, rather than the expected cycloadducts, complex rearrangement
products. The structure of one of these unusual products has been confirmed by
X-ray crystallography. A series of disubstituted nitrilimines underwent
regiospecific cycloaddition with thiobenzophenone; the structures of the
products were confirmed by X-ray crystallography.
The Conversion of Steroidal Ring B Lactones into Ortho Esters: Preparation of 7,7-Dimethoxy-6-oxaestra-1,3,5(10)-triene Derivatives
Authors: Bourke David G. , Collins David J.
Published: August 2004

17β-t-Butyldimethylsilyloxy-3-methoxy-6-oxaestra-1,3,5(10)-trien-7-one
(1), prepared in three steps from
17b-hydroxy-3-methoxy-6-oxaestra-1,3,5(10),8-tetraen-7-one (5a), was converted
via the corresponding phenolic acid into
1β-t-butyldimethylsilyloxy-5β-(2′-t-butyldimethylsilyloxy-4′-methoxyphenyl)-N,7aβ-dimethyl-N-phenyl-2,3,3aα,4,5,6,7,7a-octahydro-1H-indene-4α-carboxamide
(17c). Subjection of (17c) to a reaction sequence with methyl
trifluoromethanesulfonate, sodium methoxide/methanol, and then dry
methanol/acetic acid gave a low yield (12%) of the ortho ester
3,7,7,17β-tetramethoxy- 6-oxaestra-1,3,5(10)-triene (2b), together with
5β-(2′-hydroxy-4′-methoxyphenyl)-1β-methoxy-N,7aβ-dimethyl-N-phenyl-2,3,3aα,4,5,6,7,7a-octahydro-1H-indene-4α-carboxamide
(17e) (29%), 8% of (17a), the 1β-hydroxy analogue of (17e)
and 3% of methyl
5-(2′-hydroxy-4′-methoxyphenyl)-1β-methoxy-7aβ-methyl-2,3,3aα,4,5,6,7,7a-octahydro-1H-indene-4α-carboxylate
(11c). The outcome of this reaction sequence was complex, and very sensitive
to minor changes in conditions. Several related transformations are described,
and possible mechanistic pathways are discussed.
Halogenated Terpenoids. XXX. The Bromocamphorenic Acids and the Dibromocampholides, and their Fomation from α,α-Dibromocamphor
Authors: Carman Raymond M. , Karoli Tomislav , Venzke Brian N.
Published: August 2004

The structures of the bromocamphorenic acids obtained by oxidative
rearrangement of α,α-dibromocamphor are now corrected. The
structures of four dibromocampholides in the same series are also reported,
and a mechanism to account for the formation of the compounds is proposed.
Skeletal Rearrangements of Ring C Aromatic Diterpenoids
Authors: Cambie Richard C. , Liu Carrie C. , Rickard Clifford E. F. , Rutledge Peter S.
Published: August 2004

The structure of a naphthalene derivative obtained by rearrangement of
13-methoxytotara-5,8,11,13-tetraen-7α-ol (2) has been revised to
5-(5′-isopropyl-6′-methoxy-2′-methyl-1′-naphthyl)-2-methylpent-2-ene
(7). A minor oxidation product of 13-methoxytotara-8,11,13-triene (4) has been
identified as
4-methoxy-3,3-dimethyl-7-(1′,3′,3′-trimethyl-2′-oxocyclohexanyl)isobenzofuran-1(3H)-one
(16) and its structure confirmed by X-ray crystallography. Methyl
12-methoxypodocarpa-8,11,13-trien-19-oate (12) has been converted into an
intermediate used in the synthesis of the linear diterpenoid umbrosone
[3-(1′-hydroxy-1′-methylethyl)-5,5,9-trimethyl-5,6,7,8-tetrahydroanthracene-1,2-dione]
(15).