bluuebunny/crossref_metadata_2025 huggingface dataset:
Terpenoid constituents from two Phyllospongia spp.
Authors: Kazlauskas R , Murphy PT , Wells RJ , Daly JJ
Published: September 2010

The structures of six new C26
tetracyclic terpenoids
isolated from two Phyllospongia spp.
are described. The relative stereochemistry of one compound was solved by a
single-crystal X-ray determination.
Transference numbers for magnesium chloride at 25°C
Authors: Lee K , Kay RL
Published: September 2010

Transference numbers for
aqueous magnesium chloride at 25°C have been measured by the moving-boundary
method at concentrations up to 0.5 molar. The boundary movement was followed by
using a newly designed radiofrequency detector by means of which the boundary
velocity was determined by its passage past wire electrodes wrapped around the external
surface of the moving-boundary tube. Extrapolation to infinite dilution gives T+/0
(MgCl2, 25°C) = 0.4114 which when combined with the known limiting
conductance for the chloride ion gives the following equivalent conductances:
Λ0 (MgCl2, 25°C) = 129.78 and l.0
(Mg2+, 25°C) = 53.39. Both of these values are
independent of conductance measurements on MgCl2 but are shown to be
consistent with the latest conductance data for MgCl2.
Isomer effects in mixtures of hydrocarbons: some experimental excess volumes and enthalpies
Authors: Fenby DV , Khurma JR , Kooner ZS , Block TE , Knobler CM , Reeder J , Scott RL
Published: September 2010

Excess volumes have been
measured at 293.2 K for n- hexadecane+cyclopentane, +methylcyclopentane, +cyclohexane, +methylcyclohexane,
+trans-1,4-dimethylcyclohexane, and +2-methyl- butane, and at 298.2 K for
n-hexadecane+2,2,4-trimethylpentane. The corresponding excess enthalpies have
been measured at 298.2 and 308.2 K for n-hexadecane+cyclopentane,
+methylcyclopentane, +cyclohexane, +methylcyclohexane, and + 1,4-dimethylcyclohexane. Excess
volumes have been measured at 298.2 K for all ten binary mixtures of cyclohexane,
methylcyclopentane, n-hexane, 3-methylpentane, and
2-methylpentane; the systems cyclohexane+methylcyclopentane
and n-hexane +methylcyclopentane show double minima
in the curve of VE against x and have been measured at two lower
temperatures as well. The excess volumes show a consistent trend towards more
negative values as the number of methyl groups increases; the excess enthalpies
are more difficult to interpret.
Mutual diffusion, intradiffusion and viscosity coefficients for mixtures of cyclopentane and cyclooctane at 298.15 K
Authors: Levien BJ , Mills R
Published: September 2010

Mutual diffusion,
intradiffusion and viscosity coefficients have been measured at 298.15 K for
the system cyclopentane (1)+cyclooctane (2). The mutual diffusion coefficient
extrapolates to Do21 2.361×10-9 m s-1
for pure cyclopentane and to D°12 0.793x 10-9 m s-1
for pure cyclooctane and these values are in good agreement with the
corresponding tracer-diffusion ones. The viscosity and intradiffusion
coefficients vary from 0.415 × 10-3 kg m-1 s-1
and 3.114 × 10-9 m2 s-1 for pure cyclopentane to
2.250 × 10-3 kg m-1 s-1 and 0.546 × 10-9
m2 s-1 for pure cyclooctane. ��� It is shown that the intradiffusion and
viscosity coefficients can be related through the Stokes-Einstein equation. The
diffusion measurements have been transformed to velocity cross-correlation
coefficients and it is found that there appear to be no special associative
effects or structural features in this system.
Excess volumes for binary mixtures of n-alkanes + cyclohexane at 298.150 K by continuous dilution dilatometry
Authors: Martin ML , Symons L
Published: September 2010

The excess volumes of
binary mixtures of n-pentane, n-hexane, n- heptane, n-octane, n-nonane and n-decane+cyclohexane were measured at 298.150 K
with a continuous dilution dilatometer. The excess volumes were positive with
the exception of mixtures of n-pentane with cyclohexane for which values were
negative at all concentrations. The results have been compared with those
published recently from data obtained in three systematic studies involving pycnometry, a vibrating tube densimeter and a
semi-continuous dilatometer.
The v1/5 - v1/4 far-infrared bands of (D1)acetylene and (D2)acetylene
Authors: Braund DB , Cole ARH
Published: September 2010

Rotational lines in the v1/5
v1/4 band of DC=CH
and DC=CD have been located and measured at a spectral slit width of 0.3-0.4 cm-1.
Spectroscopic constants obtained from analysis of the lines are consistent with
more accurate constants obtained from mid- and near-infrared, and microwave
work.
The circular dichroism of a,b-unsaturated ketones. I. Circular dichroism in the singlet-singlet and singlet-triplet n «p* transitions of steroidal 4-en-3-ones
Authors: Beecham AF , Collins DJ
Published: September 2010

The circular dichroism from
22 steroidal 4-en-3-ones in cyclohexane solution has been recorded through the
wavelength range 400-265 nm. It is shown that both the singlet-triplet and the
singlet-singlet n → π* electronic transitions contribute. Through
examination of evidence from c.d. and X-ray structure analysis, it is concluded
that the conformation of the chromophore and its immediate environment remains
constant under the conditions of measurement. In three of the 6β- substituted
compounds the normal, highly structured, negative Cotton effect from the
singlet-singlet n → π* transition is modified by positive c.d. with
the same vibrational structuring. The origin of the positive contribution is
discussed.
Colouring matters of Australian plants. XXIII. A new synthesis of arylphenalenones and naphthoxanthenones
Authors: Cooke RG , Merrett BK , O'Loughlin GJ , Pietersz GA
Published: September 2010

Condensation of
naphthalene-2,7-diol with 2,4-dioxo-4-phenylbutanoic acid gives 6-hydroxy-1-oxo-9-phenyl-1H-phenalene-7-carboxylic
acid which is readily converted into the lactone and on treatment with
diazomethane forms only methyl 6-methoxy-1-oxo-9-phenyl-1H-phenalene-7- carboxylate.
Analogous reactions of other 4-aryl-2,4-dioxobutanoic acids with
naphthalene-2,7-diol or with 3,6-dimethoxynaphthalene-2,7- diol give easy
access to arylphenalenones and naphthoxanthenones related
to natural pigments.
The magnetic behaviour of titanium and vanadium hexaurea salts at low temperatures
Authors: Baker J , Figgis BN
Published: September 2010

The magnetic susceptibility
and anisotropy of the iodide and perchlorate salts of the hexaureatitanium(III)
and hexaureavanadium(III) ions have been measured between liquid helium and
ambient temperatures. The analysis of the data in terms of a model involving
the angular and radial parts of the ligand field parameters, B0/2,
B0/4 and B3/4, the spin-orbit
coupling constant, λ, and the orbital reduction parameter, k, yields
values supporting earlier studies, but having greater reliability and in better
agreement with the optical absorption spectra. It is suggested that the low
values deduced for k and λ/λ0 may be due to the operation
of a dynamic Jahn-Teller effect.
The aminolysis of p-nitrophenyl acetate by aminopyridines. Mechanisms in aqueous and aprotic solvents
Authors: Deady LW , Finlayson WL
Published: September 2010

In dimethyl sulfoxide, the
aminolysis of p-nitrophenyl acetate by aminopyridines results in amide
formation, through nucleophilic catalysis by the ring nitrogen for
4-aminopyridine, but by direct amino nitrogen attack for 2-aminopyridine (as
previously found for acetic anhydride). In water, the aminopyridines catalyse
the hydrolysis of the ester (unlike aniline, which still gives acetanilide). In
general, this occurs by nucleophilic catalysis by the ring nitrogen. Even
4-amino-2- methylpyridine reacts by this route (though 2-picoline does not)
and, of the compounds studied, only for 2-amino- 6-methylpyridine does general
base catalysis occur instead. Reasons for these mechanism changes are
discussed.
Nuclear spin-lattice relaxation in a multi-spin system. A spin 1/2 particle dipolar coupled to a spin 1 and spin 3/2 particle. 13C spin relaxation in urea
Authors: Doddrell DM , Kleinschmidt KM
Published: September 2010

Density matrix theory is
used to show that for S = 1/2, 1, 3/2 the decay of the I-magnetization (I = 4) in a
two-spin IS dipolar coupled system is governed by the differential equation
��������������� d/dt= -k1{J(ωI-ωS)+3J(ωI)+6J(ωI+ωS)}{-I0}������ ������������������-k2{6J(ωI+ωS)-J(ωI-ωS)}{-S0}
where k1 and k2
are positive constants dependent on S and the dipolar interaction constants. It
follows that if  = 0, as arises on S- irradiation, or
 = S0, as in paramagnetic transition-metal complexes,
the decay of the I-magnetization is exponential.�The theory is used to analyse 14N,2H
dipolar-induced 13C spin relaxation in deuterated urea. It is shown
that at low temperatures dipolar interactions dominate the relaxation whereas
at high temperatures spin rotation effects become important. The relaxation
times are very long; at 300 T1 is 114s.
Dipole moments, Kerr constants and solution-state conformations of di(pyridin-4-yl), di(pyridin-3-yl) and di(pyridin-2-yl) ketone
Authors: Gore PH , John IG , Pierens RK , Ritchie GLD
Published: September 2010

Experimental dipole moments
and molar Kerr constants are reported and analysed for di(pyridin-4-yl),
di(pyridin-3-yl) and di(pyridin-2-yl)
ketone as solutes in carbon tetrachloride or cyclohexane at 298 K. The
preferred conformation of di(pyridin-4-yl) ketone is
found to be very similar to those previously deduced for benzophenone and
several 4,4'- disubstituted benzophenones. For di(pyridin-3-yl)
and di(pyridin-2-yl) ketone three analogous
conrotatory structures having different relative dispositions of the nitrogen
atoms are considered. In the case of di(pyridin-3-yl)
ketone the cis-trans and trans-trans arrangements are approximately equally
abundant, but for di(pyridin-2-yl) ketone there is a
strong preference for the trans-trans conformation.
Sigmatropic rearrangements of unsaturated dixanthogens
Authors: Fielding LJ , Porter QN , Winter G
Published: September 2010

Diallyldixanthogen and di(but-2-enyl)dixanthogen are unstable compounds, and
decompose by two [3,3] sigmatropic rearrangements to the corresponding
disulfides and carbon oxysulfide. Intermediates in the rearrangements are
detected by infrared and 1H n.m.r. techniques. A minor contribution
from a four-centre mechanism is demonstrated. The stability of di(pent-4-enyl)-dixanthogen supports the suggested
mechanism for the rearrangements.
A phosphorus-31 magnetic resonance study of ligand exchange on tetrakis(hexamethylphosphoramide)zinc(II) ion
Authors: Tkaczuk MN , Lincoln SF
Published: September 2010

The rate of the associative
ligand exchange process on tetrakis (hexamethylphosphoramide)zinc(II) ion in CD2Cl2
solution, determined by 31P n.m.r. spectroscopy, is given by:
������������������� rate = 4k2[O=P(Nme2)3][Zn(O=P(NMe2)3)42+]
The characteristic kinetic
parameters are: k2(240 K) 304�17 dm3 mol-1 s-1,
ΔH2‡ 22.7�0.9 kJ mol-1, and ΔS2‡
-101�4 J K-1 mol-1. ��� The preparations of [Zn(O=P(NMe2)3)4](ClO4)2,
[Zn(O=P(OMe)3)5] (ClO4)2
and [Zn {O=P(Me)-(OMe)2}5](ClO4)2
are reported. The rate of ligand exchange upon the last two species was found
to be in the fast-exchange limit of the n.m.r. time scale.
Studies of Australian soft corals. XXII. The structures of two novel sesquiterpenes and a nor sesquiterpene from Lemnalia africana, confirmed by a single-crystal X-ray study
Authors: Bowden BF , Coll JC , Mitchell SJ , Skelton BW , White AH
Published: September 2010

The isolation of two new
sesquiterpenes (3) and (8) and a novel nor sesquiterpene (16) from Lemnalia africana
is reported. In each case, the absolute stereochemistry was deduced chemically
and spectroscopically, and confirmed by a single-crystal X-ray study on a
suitable derivative (7).
Kinetics of oxidation of reduced cytochrome c by aquacopper(II) and chlorocopper(II) complexes in the presence of oxygen
Authors: Yandell JK
Published: September 2010

The rate constants for the
oxidation of reduced cytochrome c by aquacopper(II) ion, aquachloro- copper(II)
ion and aquadichlorocopper(II) were found to be 5.7�0.3 1. mol-1 s-1,
2.3×102 1. mol-1 s-1 and 5.6xl031.
mol-1 s-1 respectively at 25�C, ionic strength 0.1 and pH
4.0. At low ratios of aquacopper(II) ion to ferrocytochrome c, when oxygen is
required to completely oxidize the cytochrome, the reaction mechanism was found
to be complex. No evidence for the involvement of copper bound to the
cytochrome was found.
Cyanidation products of organoboranes derived from linalyl acetate
Authors: Murphy R , Prager RH
Published: September 2010

The seven-membered cyclic
borane obtained from the reaction of linalyl acetate and thexylborane loses
2,3-dimethylbut-2-ene, and the resulting dialkylborane gives an alcohol on
treatment with sodium cyanide, followed by trifluoroacetic anhydride and oxidation.
The structure is confirmed by synthesis. The generality of this reaction was
investigated but, of the dialkylboranes examined, only 9-borabicyclononane
participated in the cyanidation procedure. A simple synthesis of menthone is
presented.
Central nervous system active compounds. VI. Reissert compounds as precursors of 1-(3-phthalidy1)isoquinolines
Authors: Hung TV , Mooney BA , Prager RH , Ward AD
Published: September 2010

The reactions of
isoquinoline and phthalazine Reissert
compounds with phthalaldehydic acids and their
derivatives have been investigated as a means of synthesizing 1-(3-phthalidyl)isoquinolines. Of a variety of conditions tried those
involving phase transfer were found, in general, to be the most suitable. The
products, which are analogues of the convulsant
alkaloid bicuculline, showed weak central nervous
system depressant activity.
The conformations of some organic carbonates
Authors: Chia LHL , Kwan KJ , Huang HH
Published: September 2010

Electric dipole moments and
molar Kerr constants are reported for seven organic carbonates (dimethyl
carbonate, diethyl carbonate, vinylene carbonate, diphenyl carbonate, di-p-tolyl carbonate, di-o- tolyl carbonate and t-butyl phenyl
carbonate) examined as solutes in carbon tetrachloride at 25�. The experimental
data are analysed to provide information on the probable solution-state conformations.
New metabolites from the brown algal genus Cystophora
Authors: Kazlauskas R , King L , Murphy PT , Warren RG , Wells RJ
Published: September 2010

The dichloromethane-soluble
secondary metabolites of four Cystophora species,
C. monilifera, C. congesta, C. expansa and C. scalaris,
are described. The structures of two new acyl phloroglucinols isolated from C. monilifera have been established by a
combination of spectral and chemical methods.
Coordinating properties of pyrrolic and pyridinic nitrogen with metals in aqueous solution. A calorimetric study
Authors: Aruga R
Published: September 2010

Enthalpy of complex
formation of pyrrole-2-carboxylate ligand with calcium(II), cobalt(II),
nickel(II) and copper(II) cations has been determined by direct calorimetry. By
means of the equilibrium constants, Gibbs function and entropy were also
obtained. The measurements were carried out in aqueous medium at 25�C and an
ionic strength of 1 (NaNO3). The thermodynamic quantities for
pyrrole-2-carboxylate, compared with those for pyridine-2-carboxylate obtained
previously, lead to the following conclusions. (A) The enthalpy factors which
make the metal-pyridinic ligand complexes rather stable are absent in the case
of pyrrolic ligand. The absence is probably due to the electronic structure of
the pyrrole aromatic ring. (B) The enthalpy data seem to indicate, for the
metal complexes of pyrazole and imidazole, a metal-pyridinic nitrogen bond
rather than a metal-pyrrolic nitrogen bond.
High-field 1H N.M.R. study of the four-spin system of a set of 2,3,4,5-tetrasubstituted pyrrolidines
Authors: Duewell H
Published: September 2010

The pyrrolidine ring
protons of the isomeric dimethyl 2,5-dibenzoyl-1-phenylpyrrolidine-
3,4-dicarboxylates constitute, depending on stereochemistry, either an [AX]2
or an ABXY system. The three types of spectra obtained have been analysed and
correlated with molecular structure. Evidence is given for hydrogen bonding,
between ester groups and cis-vicinal phenacyl hydrogen atoms, which leads to the stabilization
of the preferred conformers.
Preparations of 3-substituted Tetra- and Hexa-hydroazocin-2(1H)-ones and derivatives
Authors: Ridley DD , Simpson GW
Published: September 2010

3-Bromo- and
3-chloro-hexahydroazocin-2(1H)-one
undergo dehydrohalogenation rather than substitution reactions, even in the
presence of weakly basic nucleophiles like iodide and cyanide ions. A mixture
of two alkenes is formed, with the conjugated isomer, 5,6,7,8-tetrahydroazocin-2(1H)-one, predominating over the
deconjugated isomer. Only thiolate nucleophiles, for example sodium
benzenethiolate, gave substitution reactions and the resulting
3-phenylthiohexahydroazocin-2(1H)-
one was oxidized to give a mixture of diastereoisomeric sulfoxides. On
attempted Pummerer rearrangement, this mixture of sulfoxides afforded
3-phenylthio-5,6,7,8-tetrahydroazocin-2(lH)-one
rather than the expected α-acyloxy sulfide.
Regioselectivity and stereoselectivity in the reaction of cis-1,2,2-Trimethylcyclopentane-1,3-dicarboxylic anhydride (cis-camphoric anhydride) with chiral primary amines
Authors: Bell KH
Published: September 2010

The reaction between
primary amines and cis-1,2,2 trimethylcyclopentane-1,3-dicarboxylic
anhydride (3) has been shown to be regioselective for
the less hindered carbonyl group. Kinetic resolution was observed when racemic
primary amines and the (1R,3S) anhydride (3) were used. Similar
stereoselectivity was found in the alternative reaction between racemic (3) and
optically active primary amines. In both cases, the absolute configuration of
the more reactive enantiomeric amine or anhydride
could be correlated with a model (7). The use of (3) is recommended for the
prediction of the absolute configurations of racemic and optically active
primary amines.
Base effects on the stereoselectivity of the reaction of (2R,3R)-2,3-Diacetoxy- and (2R,3R)-2,3-Dibenzoyloxy-succinic anhydrides with racemic alcohols
Authors: Bell KH
Published: September 2010

A study has been made of
the effect on the stereoselectivity of the reaction of racemic alcohols with
(2R,3R)-2,3-diacetoxy- and (2R,3R)-2,3-dibenzoyloxy-succinic anhydrides, by
using various pyridine derivatives as the basic catalyst. Considerable enhancement
in stereoselectivity is observed with increasing steric bulk around the basic
centre, as for example in substituting 2-methylpyridine for pyridine. However,
if the pKa of the base used differs significantly from that of
pyridine, a decrease in stereoselectivity results.
Preparation of isobenzofuran-1(3H)-ones by decarbonylation of 1H-2-benzopyran-1,3(4H)-diones
Authors: Quinn KJ , Rae ID
Published: September 2010

3,3-Dimethyl-1H-2-benzopyran-1,3(4H)-dione (3,3-dimethylhomophthalic anhydride) is decarbonylated in the presence of aluminium chloride to
give 3,3-dimethylisobenzofuran-l(3H)-one
(3,3- dimethylphthalide) in good yield. The
5,8-difluoro anhydride reacts similarly to give the 4,7- difluoro lactone. The
precursors of the anhydrides, the 3,3-dimethyl-2,3-dihydro-1H-inden-1-ones, were prepared from
3-methylbut-2-enoic acid and the appropriate aromatic compound in the presence
of aluminium chloride. The difluorodihydroindenone
prepared in this way is accompanied by
5,8-difluoro-4-methyl-3,4-dihydronaphthalen-1(2H)-one and a mechanism is proposed to account for its formation.
Intermolecular interactions in water + acetonitrile mixtures : Evidence from the composition variation of solvent polarity parameters
Authors: Balakrishnan S , Easteal AJ
Published: September 2010

The dependence on
composition of the polarity of H2O+MeCN mixtures has been determined
from measurements of the empirical solvent polarity parameter ET. ET has been found to vary with composition in a similar
fashion to that which has been reported previously for most other H2O+non-electrolyte
mixtures for which ET data
are available. The variation of ET
with composition is interpreted in terms of the Naberukhin-Rogov structural
model for H2O+nonelectrolyte mixtures.
Torsional angles in N-substituted benzamides and related compounds by carbon-13 N.M.R. chemical shifts
Authors: Fong CW , Grant HG
Published: September 2010

The torsional angles in 30 N-substituted benzamides and related
compounds have been estimated by the use of the 13C substituent
chemical shifts of the meta and para carbon
atoms. Steric interaction between the N-substituted
groups and the ortho
hydrogen atoms of the benzene ring is the major determinant of non-planarity in
these systems. A linear relationship between steric substituent constants of
the N-substituted groups of some
benzamides and the torsional angles is proposed. Dynamic processes involving rotation
about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic
steric effect to the overall steric interaction. The preferred conformations of
some N-substituted groups is also
discussed.
Hilbert-Johnson reactions of 2,2',4',6-Tetramethoxy-4,5'-bipyrimidine
Authors: Brown DJ , Strekowski L
Published: September 2010

2,2',4',6-Tetramethoxy-4,5'-bipyrimidine
(1) was converted successively by methyl iodine into
2,4',6-trimethoxy-l'-methyl-4,5'-bipyrimidin-2'-one (2a), a single
dimethoxy-1,1'-dimethyl-4,5'-bipyrimidinedione (3 or 4; not positively
identified), 4'-methoxy-1,1',3-trimethyl-4,5'-bipyrimidine- 2,2',6-trione (5)
and 1,1',3,3'-tetramethyl-4,5'-bipyrimidine-2,2,4',6-tetrone (6e). Hydrolysis
of the first three products gave
respectively, the 1'-methyl, 1,1'-dimethyl and 1,1',3-trimethyl derivatives
(6b-d) of 4,5'-bipyrimidine-2,2',4',6-tetrone. Structures were elucidated by
n.m.r., ultraviolet and mass spectra.
The chemistry of Lauren-1-ene. III. Synthesis and properties of laurenane and 1βH-Lamenane
Authors: Eaton PJ , Lauren DR , O'Conner AW , Weavers RT
Published: September 2010

The saturated hydrocarbons
laurenane (3) and 1βH-laurenane (4) have been synthesized. Assignments of
their 13C n.m.r. and 1H n.m.r. spectra are reported and
used, with the aid of lanthanide shift reagents, to investigate conformational
mobility of these substituted fenestranes. Some examples of long-range 13C
n.m.r. substituent effects of the ε and ζ types have been noted.
Unfused heterobicycles as amplifiers of phleomycin. II. Some 2,4'-, 4,5'- and 5,5'-bipyrimidines
Authors: Brown DJ , Cowden WB , Strekowski L
Published: September 2010

Syntheses and n.m.r.
spectra are reported for derivatives of 2,4'-, 4,5'- and 5,5'-bipyrimidine,
each bearing a methoxy, methylthio, dimethylamino, β-dimethylaminoethylamino
or β-dimethylaminoethylthio substituent.
Free-radical reductions of arenediazonium ions in aqueous solution. V. Pulse-radiolytic determination of rate constants for some para-substitutedbenzenediazonium ions
Authors: Packer JE , Monig J , Dobson BC
Published: September 2010

Some rate constants for the
reduction of para-substituted benzenediazonium ions
by the radicals eaq-, ·CH2OH, (CH3)2·COH
and some semiquinone radical anions have been
measured. The substituent group has no effect on the rates with eaq-,
but as the reduction potential of the reducing radical becomes more positive,
the substituent effect increases, electron-withdrawing groups enhancing the
rates. No free halide is formed on reduction of p-BrC6H4N2+
or p-IC6H4N2+ by eaq-
or ·CH2OH.
New metabolites from Australian lichens
Authors: Chester DO , Elix JA
Published: September 2010

The depsides orcinyl
lecanorate (1) and 2'-O-methylmicrophyllinic acid (4), and the depsidone norcolensoic acid (11),
have been identified in lichens and characterized.
Quinazolines. XXV. The synthesis of 8-Chloro-2-[4-(2-furoyl)piperazin-1-yl]-6,7-dimethoxyquinazolin-4-amine hydrochloride (8-chloroprazosin hydrochloride)
Authors: Armarego WLF , Reece PA
Published: September 2010

A twelve-step synthesis of
8-chloroprazosin (3) hydrochloride starting from vanillin has been achieved in
16% overall yield (59% w/w yield). The hydrochloride is a useful internal
standard for the quantitative estimation of the drug prazosin in human plasma.
New sesquiterpenes from Caulerpa flexilis var. muelleri
Authors: Capon RJ , Ghisalberti EL , Jefferies PR
Published: September 2010

Two new monocyclic
sesquiterpenes have been isolated from the green alga Caulerpa
flexilis (Lamx) var.
muelleri (Sond.) (Wom.).
Equilibrium and transport properties of Ca(NO3)2 + (Li,K)NO3 hydrate melts: Confirmation of a mixed-alkali effect
Authors: Easteal AJ
Published: September 2010

Glass-transition
temperature, density, electrical conductivity and viscosity have been
determined as a function of the relative proportions of the two alkali metal
nitrates in the hydrate melts �������������� 0.55[Ca(NO3)2,RH2O]+0.45[XLiNO3+(1-X)KNO3]
where X is the mole
fraction of LiNO3 relative to total alkali metal nitrate, with mole
ratios (R) of water to Ca(NO3)2 of 4.090 and 6.545, at
298.15 K. For both series of melts, molar volume varies linearly with X, i.e.
is an additive function of composition. Glass-transition temperature and molar
conductivity show negative deviations from additivity, the magnitude of the
deviations decreasing with increased water content. Fluidity isotherms show
much smaller negative deviations from additivity and the magnitude of the
deviations is approximately independent of water content. ��� By analogy with the properties of network
oxide melts and glasses, the composition variation of the properties
investigated for the hydrate melts is interpreted as being indicative of a
significant mixed-alkali effect qualitatively similar to the effect which
occurs in network oxide media. The hydrate melts are closely similar in their
behaviour to fused anhydrous (Na,Tl)NO3
mixtures, and it is suggested that the observed trends in the properties of the
hydrate melts have a similar origin to that which was postulated for the
anhydrous melts.
The interaction of dimethyl sulfoxide with N-benzoyl amino acids
Authors: Fong CW , Grant HG
Published: September 2010

The interaction of dimethyl
sulfoxide with N-benzoyl amino acids in deuterochloroform has been investigated
by 13C n.m.r. spectroscopy. Examination of the chemical shifts of
the benzene ring reveals that intermolecular hydrogen bonding between dimethyl
sulfoxide and the amido-hydrogen atom increase the effective steric size of the
amino hydrogen, resulting in an increase in the torsional angle between the
benzene ring and the C(O)NHCH(R)COOH side chain. Self-association of N- benzoyl
amino acids in deuterochloroform occurs largely through two COOH...O=C hydrogen
bonds and does not involve intermolecular hydrogen bonding to the N-H proton.
Substitution reactions of nitrothiophens. IV. Limitations in scope of the SN(AEAE) reaction in thienylalkyl derivatives
Authors: Newcombe PJ , Norris RK
Published: September 2010

The reactions of
5-nitro-3-thienylethyl chloride and acetate with lithium 2-nitropropan-2-ide
(1)give excellent yields of the C-alkylate,
4-(1,2-dimethyl-2-nitropropyl)-2-nitrothophen, by the SN(AEAE)mechanism.
The cyano group is not a sufficiently activating
substituent to support the SN(AEAE)process and
4-cyano-2-thienyl-methyl and -ethyl chlorides with the salt (1) give
O-alkylated products by an SN2 mechanism. The occurrence of SN
(AEAE) reactions with other nucleophiles is difficult to prove but benzenethiolate and 4-nitro-2-thienylmethyl acetate do
react by this mechanism to give a moderate yield of 4-nitro-2-thienylmethyl
phenyl sulfide.
Structural and spectroscopic studies of transition metal nitrite complexes. IX.Crystal structures and spectroscopic properties of polymeric [Ni(C2H8N2)2-(NO2)] ClO4, its mononuclear zinc analogue, cis-Bis(ethane-1,2-diamine)(nitrito-O,O')zinc(II) perchlorate, and the complexes cis-(N,N,N',N'-Tetramethylethane-1,2-diamine)di(nitrito-O,O')-nickel(II) and -zinc(II)
Authors: Finney AJ , Hitchman MA , Raston CL , Rowbottom GL , White AH
Published: September 2010

The crystal structures of
the title compounds are reported. The complex [Ni(C2H8N2)2(NO2)]
ClO4 is found to be an infinite polymer with trans N,O-bridging
nitrite groups. The zinc analogue of this contains mononuclear units involving
a symmetrically chelated nitrite group. The two
compounds formed with N,N,N',N'-tetramethylethane-1,2-diamine
are isostructural, with the metal having a distorted
octahedral ligand environment provided by the amine nitrogen atoms and two
chelating nitrite groups. However, while the nitrite ions in the nickel complex
are chelated approximately symmetrically, the Zn-O
bonds trans to the amine nitrogen
atoms (2.30 �) are much longer than those in the cis positions (2.07 �), and an alternative description of the
geometry of the zinc complex is as a highly distorted tetrahedral arrangement
involving essentially monodentate nitrito
groups. The difference in stereochemistry between these two complexes is
apparently caused by electronic rather than steric factors, and comparison is
also made with the geometry reported for the iso-structural copper complex.
The electronic spectra of the two nickel(II) complexes are discussed in
relation to their structures, and the infrared frequencies reported for the
nitrite groups are correlated with the observed coordination geometries.
Metal exchange reactions between divalent metal ions and their dithiocarbamate complexes in dimethyl sulfoxide: a kinetic and mechanistic study
Authors: Sachinidis J , Grant MW
Published: September 2010

The kinetics and mechanism
of metal exchange between NiII, CuII, ZnII, CdII,
PbII and HgII and their dithiocarbamate complexes have
been studied in dimethyl sulfoxide. Two pathways for ligand transfer are
observed. The first involves dissociation of dithiocarbamate from the metal
complex followed by substitution at the metal ion, while the second involves
direct electrophilic attack by the metal ion on the dithiocarbamate complex.
The relative importance of the pathways depends on the stability of the complex
and the substitution lability and electrophilic character of the metal ion. The
stability of the dithiocarbamate complexes in dimethyl sulfoxide is in the
order Hg > Cu > Ni > Pb ≈ Cd > Zn.
Crystal structure of zerumbone [(E,E,E)-2,6,9,9-Tetramethylcycloundeca-2,6,10-trien-1-one]
Authors: Hall SR , Nimgirawath S , Raston CL , Sittatrakul A , Thadaniti S , Thirasasana N , White AH
Published: September 2010

The crystal structure of zerumbone, C15H22O, extracted from
the rhizomes of Zingiber zerumbet
Smith, has been determined by single-crystal X-ray diffraction at 295(1) K and
refined by least squares to a residual of 0.051 for 925 'observed' reflections.
Crystals are monoclinic, space group P21/c, a 9.036(3), b 9.712(5), c 15.643(6) �, β 97.19(3)�, Z = 4.
Although the molecule has no chiral centre, the
presence of the three trans double
bonds confers considerable distortion and rigidity on the eleven-membered ring and renders the whole molecule chiral and potentially resolvable.
Studies on reductive alkylation. Regiocontrolled synthesis of anthracene derivatives
Authors: Mander LN , Woolias M
Published: September 2010

Reductive alkylation of
2,5-dimethoxybenzoic acid, its 4-methyl derivative, and 3,5-dimethoxybenzoic acid
with methyl 2-iodomethyl-6-methoxybenzoate furnished acids (I), (2) and
(3),respectively. Oxidative decarboxylation followed
by hydrolysis led to diphenylmethane acids (4),(5)
and (6). Cycloacylation of (4) and (5) gave
1,4,8-trimethoxyanthracen-9-ol (7) and its 2-methyl derivative (8), thereby
serving as models for a regiocontrolled synthesis of anthracyclines. Cycloacylation of
(6) could only be achieved with concomitant C-acylation,
to give 4-acetyl-1,3,8-trimethoxyanthracen-9-yl acetate (9).
Generalized van der Waals theory. VII. Interface profiles and surface tension
Authors: Nordholm S , Gibson J
Published: September 2010

An equilibrium theory of fluids
based on a simple free-energy density functional developed and tested in
several preceding articles is here applied to estimate the shape and surface
tension of a gas/liquid interface in a simple LJ(12-6) fluid. The
calculation is carried out at several different levels of approximation. In the
simplest case when a step function profile is assumed the surface tension is
obtained analytically. It is too high by about 50%. By using a moment expansion
of the nonlocal free energy functional, the surface tension can be reduced to a
simple one-dimensional integral. The result is now only slightly high. Finally,
a variational calculation assuming a tanh form for the profile has been carried
out. The effect of nonlocal entropy is examined and found to cause a drop in
the surface tension by 5-10%. The results for the surface tension and width of
the profile are in good agreement with experiment and simulation (deviation c.
0%) when plotted against T/Tc.
Solar reduction of water. II. Inhibition of the hydrogenation of methyl viologen in the system water-Tris(2,2'-bipyridine)ruthenium(II) dication-ethylenediaminetetraacetic acid-platinum by sulfur compounds
Authors: Johansen O , Launikonis A , Loder JW , Mau AWH , Sasse WHF , Swift JD , Wells D
Published: September 2010

The light-induced formation
of hydrogen in the system H2O-Ru(bpy)32+-mv2+-edta-Pt
is accompanied by the hydrogenation of mv2+. This hydrogenation
process is suppressed by the addition of cysteine or
glutathione. Substantial increases in the turnover numbers of mv2+
and the yields and rates of hydrogen production are achieved.
The phase equilibrium diagram of the ternary system magnesium iodide-iodine-water
Authors: Thomas R
Published: September 2010

The phase equilibrium
diagram of the ternary system MgI2-12-H2O has
shown a single polyiodide, MgI12,,9H2O),
and a new hydrate, MgI2,9H2O, to be stable solid phases
at 0°C.
Ammine adduct and Schiff base formation in the copper(II) 1,1,1,5,5,5-Hexafluoropentane-2,4-dione-ammonia system
Authors: Anker MW , Moffett JH , Moxon NT , Gregson AK
Published: September 2010

1,1,1,5,5,5-Hexafluoropentane-2,4-dione
(Hhfa) reacts with ammoniacal solutions of copper(II) salts at room temperature
to form the ammine adducts Cu(hfa)2,NH3 and Cu(hfa)2,2NH3,
and at elevated temperatures or on standing to form the Schiff base complex Cu(hfacim)2
(Hhfacim = 1,1,1,5,5,5-hexafluoro-4-aminopentan-2-one) The magnetic
susceptibility data for Cu(hfacim)2 suggest the presence of exchange
interaction and is best explained by using a S = � Heisenberg chain model with
J=-0.18 cm-1.
A proton magnetic resonance study of ligand exchange on Pentakis(N,N-diethylacetamide)dioxouranium(VI)
Authors: Hounslow AM , Lincoln SF , Marshall PA , Williams EH
Published: September 2010

Pentakis(N,N-diethylacetamide)dioxouranium(VI)
bisperchlorate, [UO2(AcNEt2)5] has been
isolated. Proton N.M.R. spectroscopy shows that, in the presence of excess free
ligand, [UO2- AcNEt2)5]2+ is the
greatly predominant dioxouranium(V1) species in both CD2Cl2
and CD3CN solutions. The rate of ligand exchange is independent of
free ligand concentration as shown by the rate law
exchange rate = 5k1[UO2(AcNEt2)52+]where in CD2Cl2
solution k1(265 K) = 54.8 � 8.3 s-1, ΔH.‡ = 68.3 �
1.2 kJ mol-1 and ΔS‡ = 47.1 � 4.6 JK-1 mol-1.
Somewhat different values for these parameters are obtained in CD3CN
solution. These data are compared with similar data for other dioxouranium(VI)
systems, and mechanistic comparisons are made.
Lone-pair cooperativity in the N-alkylation of some derivatives of 2,2'-biimidazole
Authors: Deady LW
Published: September 2010

The relative rates of N-alkylation of
1,1'-dimethyl-2,2'-biimidazole (6), 5,6-dihydrodiimidazo- [1,2-a:2',1'-c]pyrazine (7) and 6,7-dihydro-5H-diimidazo[l,2-a:2',1'-c][l,4]diazepine
(8) with a variety of alkylating agents are reported. Irrespective of the alkylating
agent, the order of reactivity was (8) (where the biimidazole
has an additional three-carbon bridge) > (7) (two-carbon bridge) > (6)
(no bridge), with a maximum of (8)/(6) = 317 for reaction with
chloro(methoxy)methane. Since reaction of (8) is most susceptible to steric
hindrance, but where the nitrogen lone pairs are in close proximity, these
results support the idea of lone-pair cooperativity
in the alkylation reactions. Variation in the rate ratios with changes in
alkylating agent are discussed.
Conformational analysis of the products of 1,4 addition of Tri(phenylthio)methyllithium to α,β-unsaturated ketones. The X-ray structuredetermination of 4-Phenyl-5,5,5-tri(phenylthio)pentan-2-one
Authors: Manas AB , Smith RAJ , Simpson J
Published: September 2010

Iterative analysis of the
second-order ABX spin system in the 1H n.m.r. of the title compound
gave coupling constants which are consistent with a conformation involving a
H-C-C-H dihedral angle of about 90�. The structure was confirmed by X-ray
analysis. The 1H n.m.r. of the related compounds
2,2-dimethyl-5-pheny1-6,6,6-tri(phenylthio)hexan-3-one
and 1,3-diphenyl-4,4,4-tri(pheny1-thio)butan-1-one were also analysed and found
to have similar conformational characteristics.
Central nervous system active compounds. X. Some aspects of the photochemical rearrangement of N-alkylsuccinimides to hexahydroazepinones
Authors: Mooney BA , Prager RH , Ward AD
Published: September 2010

The synthetic potential for
the photolysis of alkylsuccinimides to give
6-substituted hexahydroazepine-2,5-diones is investigated. The reaction
generally proceeds poorly, particularly when phenyl, cyano
or ethoxycarbonyl groups are present. Fragmentation and
intramolecular disproportionation reactions are
identified as major side reactions.
Two new cembrane diterpenes from a soft coral (Sarcophyton species)
Authors: Kazlauskas R , Baird-Lambert JA , Murphy PT , Wells RJ
Published: September 2010

Two new cembrane
diterpenes, related to sarcophine, have been isolated
from a soft coral (Sarcophyton
sp.). Structures were solved primarily by spectral methods. The pharmacological
profile of one metabolite (5) is briefly discussed.
Two cembranes from Cespitularia species (soft coral)
Authors: Burns KP , Kazlauskas R , Murphy PT , Wells RJ , Schonholzer P
Published: September 2010

Two new cembranolides,
(1R,2S,3E,7R,8R,11E,14S)-7,8-epoxy-14-hydroxycembra-3,11,15-trien-17,2-olide
and (lR,2R,3E,7R,SR,11E,14R)-7,8-epoxy-14-hydroxycembra-3,11,15-trien-17,2-olide,
have been isolated from separate species of Cespitularia (soft coral).
Two new furans from the brown alga Acrocarpia paniculata: the use of 4-phenyl-4H-1,2,4-triazoline-3,5-dione to determine the substitution pattern of a furan
Authors: Kazlauskas R , Murphy PT , Wells RJ , Gregson RP
Published: September 2010

The dichloromethane-soluble
extract of the brown alga Acrocarpia paniculata has yielded two homologous branched chain
lipids containing a furan ring. Reaction of a substituted furan with
4-phenyl-4H-1,2,4-triazoline-3,5-dione to yield an alkyl 2-ene-1,4-dione was
used to determine the orientation of substituents on a 2,3,5-substituted furan.
On the equivalence between the point-charge electrostatic model and the angular-overlap model
Authors: Kibler MR
Published: September 2010

The parametric equivalence
between the point-charge electrostatic model and the angular-overlap model
previously derived by the author for the n/N configuration in
arbitrary symmetry is extended to the case of the n/Nn'l'N'
configuration. The equivalence between the two models is discussed from a
practical viewpoint.
The crystal and molecular structures of the bispyridine and 1,10-phenanthroline adducts of Bis(ethyl 3-mercaptobut-2-enoato)nickel(II)
Authors: Sachinidis J , Mackay MF , Grant MW
Published: September 2010

X-ray analyses of monoclinic crystals of the bispyridine and 1,10-phenanthroline adducts of the
monothioacetylacetonate complex bis(ethyl 3-mercaptobut-2-enoato)nickel(n), Ni(eosm)2,* have
defined their structures. Crystals of the bispyridine adduct Ni(eosm)2,py2, C22H28N2NiO4S2,
belong to the space group P21/c with a 8.865(6), b 15.758(4), c 9.136(3)Ǻ, β 109.18(4)°, Z 2.
Crystals of the 1,10-phenanthroline adduct Ni(eosm)2,phen, C24H26N2NiO4S2, belong to the space
group P21c with a 12.451(2), b 16.949(1), c 15 5921(2) Ǻ, β 130.97(1)°, Z 4. The structures were
refined with diffractometer data measured with Cu Ka radiation to R 0.047 (1962 terms) for the
bispyridine adduct and R 0.061 (3115 terms) for the phenanthroline adduct. The geometry about
the nickel in each complex is distorted octahedral. The molecule of the bispyridine adduct has exact
rn symmetry with the two sulfur atoms cis-equatorial and the nitrogen atoms axial. In the phenan-
throline adduct, pairs of sulfur, nitrogen and oxygen atoms are in cis configurations. In the bis-pyridine adduct, the Ni-N bond lengths, 2.153(3) and 2.182(4) Ǻ, are significantly longer than those
in other bispyridine adducts of nickel(II) species. It is suggested that the long Ni-N distances reflect
the relative instability of the bispyridine adduct, and thermodynamic data are presented to support
this.
Thienoisothiazoles. II. The synthesis of 5-alkylthioisothiazoles and the preparation of Thieno[3,2-d]isothiazole derivatives
Authors: James FC , Krebs HD
Published: September 2010

Alkylation of the reaction
product of sodium 3-iminobutyronitrile and carbon disulfide produces alkyl
2-cyano-3-iminodithiobutyrates (1) in moderate yield, which on iodine oxidation
afford 5-alkylthio-3-methylisothiazole-4-carbonitriles (2b-e). Ethyl 4-amino-3-methylthieno[3,2-dliso-
thiazole-5-carboxylate (3a) which was obtained by cyclization of ethyl
2-(4-cyano-3-methylisothiazol- 5-ylthio)acetate (2c) yields
3-methylthieno[3,2-d]isothiazole (3f) on deamination, hydrolysis and decarboxylation. This compound
forms a 5-nitro and 5-bromo derivative. The position of the substituents was
verified by synthesis. On reduction with hypophosphorous
acid, 3-methylthieno- [3,2-d]isothiazole and some of its derivatives readily ring-open,
yielding stable 3-acetimidoylthio-phen-2-thiols (4d-g), which are useful
intermediates for the preparation of 3-acetyl-2-mercaptothiophen derivatives.
Ring-opening of the isothiazole ring in
3-methylthieno[3,2-d]isothiazole (3f) and its 5-bromo
derivative (3m) occurs during lithiation reactions,
resulting in the formation of 3-acetyl-2-butylthiothiophen, isolated as the thiosemicarbazone (4c), and
3-acetyl-2-butylthio-thiophen-5-carboxylic acid (4b) respectively.
Metal-hydroxide promoted hydrolysis of activated esters. Hydrolysis of 2,4-dinitrophenyl acetate and 4-nitrophenyl acetate
Authors: Buckingham DA , Clark CR
Published: September 2010

A range of exchange-labile and
non-labile metal-hydroxide species readily promote the hydrolyses of
2,4-dinitrophenyl acetate and 4-nitrophenyl acetate. Kinetic studies (25�C, I 1.0 mol dm-3 NaClO4)
show that these processes follow shallow Bronsted slopes (β 0.33 and 0.40
respectively) which extend over a range of 1010 in nucelophile
basicity. A correlation is reported which allows the prediction of reaction
rates between [CO(NH3)5OH]2+ and other
activated charge-neutral carbonyl compounds.
Stereoselective total synthesis of (±)-isocostic and (±)-3-oxoisocostic acids
Authors: Cruz R , Martinez RM
Published: September 2010

Stereoselective
total synthesis of the title compounds, two new sesquiterpenes isolated from a Mexican
plant, are described. The key step in the synthesis is based on classical
santon in syntheses by the stereoselective Michael addition of the potassium salt
of ethyl α-cyanoacetate to the dienone(4), to give the cis
adduct (5), in an 8 : 2 ratio with the trans isomer. Further appropriate transformation
of this cis adduct (5)
leads to formation of either isocostic acid (1) or 3-oxoisocostic acid (2).
Crystal structures of two lactones of the bicyclo[2,2,2]octane series
Authors: Carman RM , Smith SS , Kennard CHL , Smith G , White AH , Skelton BW
Published: September 2010

The crystal structures of
two γ-lactones of the bicyclo[2,2,2]octane series, endo-3-carboxy-exo-5- iodobicyclo[2,2,2]octane-2,6-carbolactone (2;
R = CO2H) and exo-3-methoxycarbonyl-endo-5-acetoxybicyclo[2,2,2] octane-2,6-carbolactone
(7b), have been determined by direct methods from three-dimensional X-ray data
and refined by least-squares to final residuals of 0.033 (2; R = CO2H)
and 0.036 (7b) for 1918 and 630 'observed' reflections respectively. Crystals
for (2; R = CO2H) are monoclinic, space group P21/c with
Z 8 in a cell of dimensions a
7.192(2), b 23.785(8), c 13.199(5) �, β 105.35(2)�, while
(7b) crystallizes in the orthorhombic space group P212121
with Z 4 in a cell of dimensions a 13.347(7),
b 11.839(7), c 8.227(11) �.
The crystal structures of 1,3-Diphenylpropane-1,2,3-trione, 1,4-Diphenylbutane-1,2,3,4-tetraone, 2,4-Dihydroxy-2,5-diphenylfuran-3(2H)-one and 3,3-Dihydroxy- 1,4-diphenylbutane-1,2,4-trione
Authors: Beddoes RL , Cannon JR , Heller M , Mills OS , Patrick VA , Rubin MB , White AH
Published: September 2010

As a contribution towards a
study of the relative disposition of adjacent carbonyl groups in polycarbonyl compounds, the crystal structures of
1,3-diphenylpropane-1,2,3-trione (1), 1,4-diphenyl- butane-1,2,3,4-tetraone
(3), 2,4-dihydroxy-2,5-diphenylfuran-3(2H)-one
(benzoylformoin) (7) and
3,3-dihydroxy-1,4-diphenylbutane-1,2,4-trio (8) have been determined by X-ray
diffraction from diffractometer data at 295 K and
refined by least-squares techniques to residuals of 0.036 (942 'observed'
reflections), 0.029 (979), 0.067 (941) and 0.045 (1661), respectively. Crystals
of 1,3-diphenylpropane-1,2,3-trione are triclinic, P1, a 9.756(4), b 8.813(3), c 8.303(3) �,α
68.56(2), β 67.53(3), γ 89.11(3)�, Z 2. Crystals of
1,4-diphenylbutane-1,2,3,4-tetraone are monoclinic P21/c, a 10.641(2), b 8.381(2), c 14.710(4) �,
β 91.70(2)�, Z 4. 2,4-Dihydroxy-2,5- diphenylfuran-3(2H)-one also forms monoclinic crystals, P21/c, a 5.741(4), b 9.276(7), c 24.31(2) �,
β 106.26(5)�, Z 4. Crystals of 3,3-dihydroxy-1,4-diphenylbutane-1,2,4-trine
are triclinic, P1, a 13.08(1), b 12.43(1), c 8.895(8) �, α 82.54(8), β 81.87(7), γ 78.61(7)�, Z
4.
The regiospecific cycloaddition of 8,8-dimethylisobenzofulvene with isobenzofuran, 1-methylisobenzofuran and 1,3-dimethylisobenzofuran
Authors: Warrener RN , Evans DAC , Paddon-Row MN , Russell RA
Published: September 2010

The mixed 1 : 1 adduct formed upon
reaction of isobenzofuran with
8,8-dimethylisobenzofulvene is shown to have structure (5) resulting from a [10
+ 8] cycloaddition in which the isobenzofulvene
serves as the 10 π reagent and the isobenzofuran as the 8 π reagent. The reaction
occurs stereospecifically and forms exclusively the endo adduct. Lanthanide-induced
shift spectroscopy, 13C n.m.r. and 1H n.m.r.
spectroscopy, and deuterium-labelling techniques have been used to establish
this structure. The structure of the adducts (24) and (26) derived from
1-methylisobenzofuran and 1,3-dimethylisobenzofuran, respectively, have also
been established. A PMO treatment of this reaction correctly predicts the
structure of these products including the regiochemistry
of the product (24) formed from 1-methylisobenzofuran.
Bromination of 5a-lanost-8-en-3-one and 5a-lanost-8-ene-3,7,ll-trione
Authors: Collins J , Cooper PS , Gall RE , Georges A
Published: September 2010

Monobromination of 5α-lanost-8-en-3-one
(la) under kinetic conditions gave exclusively the 2β- bromo ketone (3a)
whilst under equilibrium conditions the product contained 85% of the 2α-bromo
ketone (2a). Monobromination of 5a-lanost-8-ene-3,7,11-trione (1b) under
kinetic conditions gave the 2a-bromo ketone (2b); 33% of the 2β-bromo
ketone (3b) was formed under equilibrium conditions. The configuration assigned
to the bromo ketones (2b) and (3b) has been confirmed by reduction with sodium
borohydride and treatment of the derived bromohydrins (4b) and (6b) with base
to give the 2β,3β-epoxide (5b) and the 3-ketone (1b) respectively.
Cleavage of the 2β,3β(-epoxide (5a) with acetic acid gave 2α-acetoxy-5α-lanost-8-en-3β-ol
(7) as the major product and 3α-acetoxy-5α-lanost- 8-en-2β-ol
(a), in a boat like conformation, as the minor product.
Chemistry of the Podocarpaceae. LXII. Bromo azide adducts of 12-Methoxypodocarpa-6,8,11,13-tetraenes
Authors: Cambie RC , Robertson JD , Rutledge PS , Woodgate PD
Published: September 2010

The addition of bromine
azide to some 12-methoxypodocarpa-6,8,11,13-tetraenes
gives 6β-bromo-7α-azido adducts with stereochemistry opposite
to that expected.