R. Chong, R. W. Gray, R. R. King and W. B. Whalley, J. Chem. Soc. C, 1971, 3571 DOI: 10.1039/J39710003571
The action of alkali on the nickel 1,19-dimethyltetradehydrocorrin salts in air yields the neutral nickel 1,19-dimethyl-5-ketotridehydrocorrins, and a variety of other reactions yield the 15-substitution products of the 5-keto-compounds, e.g. the 15-formyl derivative from the action of chloroform and alkali on the original salts, the 15-cyano-derivative from the action of cyanide and the 15-nitro- and 10,15-dinitro-derivatives from nitrations. In all these cases intermediate products were recognised, and in the cyanide reaction, a stable radical was isolated which was converted into the nickel 5-cyano-1,19-dimethyltetradehydrocorrin bromide with hydrobromic acid. A stable nickel 5,15-dicyano-radical was also isolated which was converted into the nickel 5,15-dicyano-1,19-dimethyltetradehydrocorrin perchlorate with perchloric acid. The nickel 5-cyano- and 5,15-dicyano-1,19-dimethyltetradehydrocorrin iodides yielded the corresponding nickel 5-cyano- and 5,15-dicyano-porphins on thermolysis. The dibromo-derivative of the original nickel tetrahydrocorrin salt was isolated as the unstable perbromide, and this and the unstable chlorination product were converted into the 5,15-dimethyl derivative with lithium copper methyl. Thermolysis of the nickel 1,19-dimethyltetradehydrocorrin chlorides to the 2,3-oxido-derivatives of the corresponding nickel 20-methyl-2,3-chlorins along with the meso-unsubstituted nickel porphins is shown to be a general reaction.
The sulphides formed by the respective additions of ethanethiol and benzenethiol to some chloronobornadienes are converted into the corresponding sulphones without change in stereochemistry. The only exceptions are the oxidation, with hydrogen peroxide in acetic acid, of 1,4,5,6,7,7-hexachloronorborn-5-en-2-endo-yl phenyl sulphide to afford the 2-exo phenyl sulphone, and of 1,2,3,5-endo,6,6-hexachloronoborn-2-en-7-syn-yl phenyl sulphide to give an epimeric mixture of the corresponding 7-syn and 7-anti phenyl sulphones. Product sulphones have been treated with potassium t-butoxide in t-butyl alcohol in an effort to effect epimerisation, and to provide evidence about the thermodynamic stability of individual sulphones. It is probable that in the presence of potassium t-butoxide in t-butyl alcohol, many of the derived carbanions have complete configurational stability, and hence the sulphones are not epimerised.
The deamination of methyl 4-amino-4-deoxy-α-D-glucopyranoside with nitrous acid gives methyl α-D-glucopyranoside (major product), methyl β-L-altrofuranoside, 4,5-anhydro-D-galactose, and methyl 3-deoxy-3-formyl-α-D-xylofuranoside. Deamination of 2-amino-1,5-anhydro-2-deoxy-D-glucitol gives 1,5-anhydro-D-glucitol as the major product. Participation of the ring oxygen atom dominates the reactions of these and related compounds, in which the equatorial amino group is at C-2 or C-4.
A series of neutral and acidic stilbene derivatives was synthesised from an alkylated phosphonium salt and some substituted benzaldehydes and heteroaromatic aldehydes. The substances showed potential anti-inflammatory activity, but were inactive as lipid catabolic agents.
The synthesis and biological evaluation of flexible oestrone analogues, for example trans-3-p-methoxystyryl-2-methylcyclopentan-1-one (VIII), are described. The mass spectral fragmentation of these model compounds is discussed in the context of the similar breakdown observed for the related steroidal molecules.
3-Diazopropene alkylates 3-cyanocoumarin, giving 4-allyl-3-cyanocoumarin. The pyrazole formed by isomerisation of 3-diazopropene slowly adds to 4-allyl-3-cyanocoumarin, giving 3-cyano-4-[2-methyl-2-(pyrazol-1-yl)-ethyl]coumarin (III), this addition being catalysed by 3-diazopropene acting as a nitrogen base.
The αβ-dibromides from o-cyano-trans-cinnamonitrile, the corresponding dicarboxamide and the two cis-amidenitriles are labile and readily undergo stereospecific elimination and/or cyclisation reactions with wate or base. In this way, the cis- and trans-isomers of 3-cyanomethylenephthalide and of α-bromo-o-cyano-cinnamonitrile have been obtained.
Monoethers of hydroquinone and of catechol, in which the aromatic hydrogen atoms are hindered towards electrophilic substitution by bulky substituents, are smoothly converted into the corresponding quinones and alcohols on treatment with nitrous acid. The mechanism of this reaction has been elucidated with the aid of appropriate 18O-labelled compounds. In certain cases dialkyl ethers are similarly converted into quinones by nitrous acid. The mild conditions needed for these dealkylations makes the method of potential value for compounds with the appropriate substitution pattern.
Hexafluorobicyclo[2,2,0]hexa-2,5-diene is an active dienophile in the Diels–Alder reaction, reacting at room temperature with 1,3-diphenylisobenzofuran, cyclopentadiene, furan, pyrrole, αα-dimethylfulvene, cyclohexa-1,3-diene, 2,3-dimethylbuta-1,3-diene, 2-methylbuta-1,3-diene, and buta-1,3-diene to give 1 : 1 adducts, and to give 1 : 2 adducts, except with the least reactive dienes, butadiene and cyclohexadiene. Reaction times vary from a few hours with the most reactive dienes, 1,3-diphenylisobenzofuran and cyclopentadiene, to several months with the least reactive ones, butadiene and cyclohexadiene. It is argued, on the basis of spectroscopic data, that reaction occurs by exo-addition to the bicyclo[2,2,0]hexa-2,5-diene, and by exo-addition to the cyclic dienes. This is rationalized in terms of steric factors operating in the transition state.
The n-propyl homologue of Δ1-tetrahydrocannabinol (Δ1-THC) has been isolated from Cannabis sativa L. The structure of the compound was deduced by i.r., n.m.r., and mass spectroscopy, and was confirmed by synthesis. It has only one-fifth of the activity of Δ1-THC in the mouse catalepsy test, and although present in amounts comparable to Δ1-THC it probably makes only a small contribution to the effects produced by the consumption of crude cannabis.
C.d. measurements are of use in characterising these compounds. In the α-apo-series the chirality of the styrene chromophore is the controlling feature and the dependence of conformation on temperature is clearly shown.
Dehydration of the title alcohol with toluene p-sulphonic acid in benzene yields a yellow dimer identified as trans-2,2′-dioxo-3,3′,4,4′,5α,5′β-hexaphenyl-1,1′-bi(cyclopentenylidene)(IV). Irradiation in sunlight causes isomerisation about the central double bond and the cis-isomer obtained (IX) is thermally reconverted into the trans at 185°. A second dimer isolated from the same reaction is formulated as 2,3,3a,5,6-pentaphenyl-3a,3b,6a,10b-tetrahydrobenz[e]-as-indacene-1,4-dione (XIII). Dehydration of the title alcohol with acetic acid–sulphuric acid yields a blue dehydro-dimer, 3-hydroxy-1,2,5,6,10b-pentaphenyldihydrobenz[e]-as-indacen-4-one (XIV), whose allyl ether undergoes a Claisen rearrangement and an internal Diels–Alder addition. The mass spectra of two dimethoxylated analogues (XXIX) and (XXX) are discussed.
The effects of variation in the steric and electronic properties of a number of heterocyclic unidentate tertiary phosphine ligands on their ability to form five-co-ordinate tris(phosphine) complexes with nickel(II), palladium(II), and platinum(II) dihalides, have been studied.In contrast to 5-methyl- and 5-ethyl-5H-dibenzophosphole (I; R = Me, Et) which give rise to a series of five-co-ordinate complexes with the above halides, both 5-isopropyl- and 5-t-butyl-5H-dibenzophosphole (I; R = Pri, But) form only four-co-ordinate complexes of type (phos)2MX2. The nickel(II) dihalide complexes of this type have a tetrahedral structure, indicated by their magnetic and spectroscopic properties. 1H N.m.r. studies show that in solution in deuteriochloroform, the four-co-ordinate PdIIBr2 complexes of both the phosphines (I; R = Pri) and (I; R = But) have the trans-configuration and the PtIICl2 complex of (I; R = But) also has this configuration, whereas the PtIICl2 complex of (I; R = Pri) has the cis-configuration.2,8-Dimethoxy-5-phenyl-5H-dibenzophosphole (II) resembles 5-phenyl-5H-dibenzophosphole (I; R = Ph) in forming four-co-ordinate, tetrahedral, nickel(II) dihalide complexes.10-Methyl-10-phenoxaphosphine (IV; R = Me) forms five-co-ordinate tris(phosphine)MX2 complexes with NiIICl2, PdIIBr2, and PtIICl2. 10-Ethyl-10-phenoxaphosphine (IV; R = Et) forms five-co-ordinate complexes apparently only with NiIIBr2 and NiIIl2, four-co-ordinate species being formed with NiIICl2 and NiII(NCS)2 and also with PdIIBr2 and PtIICl2. 10-Phenyl-10-phenoxaphosphine (IV; R = Ph) forms only four-co-ordinate complexes with nickel salts.The seven-membered cyclic triarylphosphine, 10,11-dihydro-5-phenyl-5H-dibenzo[b,f]phosphepin (V) is unusual in forming diamagnetic, square-planar, nickel(II) dihalide complexes.
High resolution i.r. spectrometry gives useful information about the structures of steroidal microbiological hydroxylation products. The polyketones formed by mild oxidation of the hydroxylation products are examined in the CO stretching and –CO–CH2– scissoring regions. Interpretation of the spectra by the characteristic group frequency approach is valid provided that the occurrence of interactions between carbonyl groups is recognised in predicting band positions and intensities. The hydroxylation products are most usefully studied, as dilute solutions, in the O–H stretching region. With compounds in which strong intramolecular hydrogen bonding occurs, the structures are almost uniquely defined by the characteristics of the O–H absorptions.
Phenylphosphinidene, formed in the decomposition of phenylphosphinic anhydride, has been trapped by reaction with benzil to give a spirophosphole (4).Phenylphosphinic acid and pentaphenylcyclopentaphosphine react readily by an ionic mechanism to give phenylphosphine and phenylphosphonic anhydride. The two reactions provide an explanation of the thermal decomposition of monosubstituted phosphinic acids to give phosphines and phosphonic acids.Phosphorous and hypophosphorous acid also react with pentaphenylcyclopentaphosphine to give phosphine and phenylphosphine together with a complex mixture of other products.Free-radical abstraction of hydrogen from phenylphosphinic acid converts it into pentaphenylcyclopentaphosphine and polymeric phenylphosphonic anhydride. Phenylphosphine is similarly converted into the polyphosphine in good yield.
The o.r.d. and c.d. spectra of 1,1′-binaphthyl in ethanol solution have been determined in the region 208–320 nm. Comparison of the curves with those of substituted 1,1′-binaphthyls of established chirality leads to the conclusion that the dextrorotatory (λ= 589 nm) enantiomer of this, the parent, compound has the S-configuration. This result is in accord with that arrived at by chemical correlation with a substituted 1,1′-binaphthyl in which the configuration was assigned by X-ray crystallographic methods.
The reaction of triphenylphosphine and an excess of dimethyl acetylenedicarboxylate gives in addition to the 2H-phosph(V)ole (1), a second product—the cyclopentenylidenephosphorane (2). Reduction of (2) to the dihydro-compound (7) followed by base-catalysed elimination of methanol, gives the cyclopentadienylidenephosphorane (8). The i.r., u.v., n.m.r., and mass spectra of these compounds are discussed.
The lignan, helioxanthin (III), has been synthesized from 2-bromo-4,5-methylenedioxyphenylpropiolic acid (VII) by treatment with dicyclohexylcarbodi-imide to give the dibromophenylnaphthalenedicarboxylic acid anhydride (VIII), followed by reductive debromination to the diol (VI) and selective oxidation by silver carbonate–Celite to the lactone (III). Some by-products obtained in the conversion of (VII) to (VIII) are described.
Autoxidation of phenols, catalysed by complexes formed from copper salts and amines, gives products arising from both one- and two-electron abstraction. Oxidation products depend markedly on reaction conditions, but not on the structure of the catalyst. The relevance of these reactions to some enzyme processes is mentioned.
