摘要:

Benzenesulfenyl chloride adds diaxially to 5α-cholest-2-ene (1) yielding 2β-chloro-3α-(phenylthio)-5α-cholestane (3). Assuming that the reaction proceeds via the episulfonium ion (2), this allows the inclusion of these species within the scope of the diaxial opening rule. On heating,3undergoes rearrangement to 3β-chloro-2α-(phenylthio)-5α-cholestane (4). This reaction is the first instance of a diaxial → diequatorial rearrangement of β-halothioethers.Mild oxidation of3gives a mixture of the two sulfoxides epimeric at the sulfur atom (16aand16b). On heating, both sulfoxides suffer pyrolytic elimination, without any sign of diaxial → diequatorial rearrangement. A major product of the elimination, evidently 2-chloro-5α-cholest-2-ene (18), was found to be formed a little more readily from theS-sulfoxide (16b) than from theR-isomer (16a). This observation is in accord with the conclusion of previous investigators that the elimination of the sulfenic acid from an alkyl sulfoxide involves bond formation between the hydrogen and sulfinyl oxygen during the rate determining stage (cf.19).

ISSN:0008-4042    

DOI:10.1139/v68-001

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

p-Methoxy- andp-nitro substituted analogues (1band1c) of the diaxial β-chlorothioether 2β-chloro-3α-(phenylthio)-5α-cholestane (1a), have been prepared and found to undergo the diaxial → diequatorial rearrangement. The rates of rearrangement of these compounds show the sequencep-methoxy > H >p-nitro. It is concluded that the transition state for the rearrangement is polarized in the sense of a sulfonium chloride (3). The rearrangement of1ais 1600 times faster in butanol than in decalin (at 110°). There is thus no inherent insensitivity to solvent change in a rearrangement in which there may be a "four-atom arrangement" in the transition state, a conclusion relevant to previous work on the diaxial → diequatorial rearrangement of 1,2-dibromides (1). It was further found that the nitro group slowed the rearrangement (at 110°) more in butanol than in decalin, an observation regarded as consistent with, but not requiring, the incursion of a merged ion-pair, cyclic concerted mechanism.

ISSN:0008-4042    

DOI:10.1139/v68-002

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The alkaloids ofLycopodiumalopecuroidesL. have been examined and seven alkaloids isolated. These include the known alkaloids lycopodine, lycodoline, and clavolonine, and three previously unreported alkaloids, alopecurine, debenzoylalopecurine, and alopecuridine. Anhydrolycodoline, previously obtained as a degradation product of lycodoline, was also isolated. The properties of the new alkaloids are described.

ISSN:0008-4042    

DOI:10.1139/v68-003

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Infrared spectra show both free and hydrogen bonded hydroxyl absorption in severaltrans-2-alkoxy-3-hydroxytetrahydrofurans. The extent of non-bonded hydroxyl is greater than that of bonded hydroxyl. Suggestions are made of possible conformations which might account for the infrared data.

ISSN:0008-4042    

DOI:10.1139/v68-004

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The reaction between olefins,N-chloroacetamide or 1,3-dibromo-5,5-dimethylhydantoin, and hydrogen peroxide affords β-halohydroperoxides in good yields. These compounds react extremely rapidly in basic solution to give products which depend upon their structure. The 3-halo-2,3-dimethyl-2-butyl hydroperoxides form 2,3-dimethyl-3-hydroperoxy-1-butene and from the 2-halo-1,2-dimethylcyclohexyl hydroperoxides 1-methyl-2-methylene-cyclohexyl hydroperoxide is obtained. No allylic hydroperoxide can be detected from the reaction between base and 3-bromo-2-methyl-2-butyl hydroperoxide. Mainly cleavage products, acetone and acetaldehyde, are formed together with some 2,3-epoxy-2-methylbutane. The reaction between base and 2-bromo-1-phenylethyl hydroperoxide gives styrene oxide, benzoic acid, and some benzaldehyde. Fromtrans-2-bromocyclohexyl hydroperoxide,trans-2-bromocyclohexanol, cyclohexene oxide, and sometrans-1,2-cyclohexanediol are obtained upon reaction with base. No evidence for the formation of the allylic hydroperoxide was obtained.

ISSN:0008-4042    

DOI:10.1139/v68-005

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The mode of scission ofcis- andtrans-3-methoxycyclohexene oxides by hydrogen chloride, hydrogen bromide, ammonia, acetic acid, and methanol (under both acidic and alkaline conditions) has been examined using vapor-phase chromatography to detect and isolate minor isomers. Approximately 10% of the product from opening of thetransoxide is formed by attack at position-2 with each of these nucleophiles, whereas opening of thecisoxide proceeds exclusively by attack at position-1. The results are interpreted as reflecting very similar transition states for all of these reactions, with differences in product distributions for the two oxides being governed by the inductive effect of the methoxyl group and by steric factors in the corresponding transition states.

ISSN:0008-4042    

DOI:10.1139/v68-006

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The photochemical behavior of 1,1-diphenylindene and 1,1-dimethylindene has been studied. The former undergoes efficient rearrangement on direct irradiation or on acetophenone sensitization, forming 2,3-diphenylindene and 1,2-diphenylindene. In contrast, 1,1-dimethylindene gave no detectable products of methyl migration but formed dimeric cyclobutanes on sensitized and direct photolysis. The structures of the two dimers formed in the sensitized reaction were assigned from their nuclear magnetic resonance spectra. It was also demonstrated that hydrogen, like methyl, migrated inefficiently if at all in this system. This difference in migratory aptitudes is discussed in terms of orbital symmetry of the indene system.

ISSN:0008-4042    

DOI:10.1139/v68-007

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

An investigation was made of the low molecular weight carbohydrates of potato, Netted Gem variety. The material soluble in 80% alcohol was fractionated and separated by a combination of charcoal–Celite column and paper chromatography. Fifteen major components were isolated and characterized, and five minor components were detected. The major components were galactose, glucose, fructose, myoinositol, and eleven oligosaccharides, namely, sucrose, melibiose (Galp1 → 6 Gp), maltotriose (Gp1 → 4 Gp1 → 4 Gp), digalactosyl glycerol (Galp1 → 6 Galp, 1 → 1 Glyc), glucosyl → myoinositol, raffinose (Galp, 1 → 6Gp1 → 2 Fruf), planteose (Galp, 1 → 6 Fruf2 → 1 Gp), galactinol (D-1-O-α-D-galactopyranosyl-myoinositol), manninotriose (Galp1 → 6 Galp, 1 → 6 Gp), stachyose (Galp1 → 6 Galp1 → 6 Gp, 1 → 2 Fruf), and trigalactosyl glycerol (Galp1 → 6 Galp1 → 6 Galp1 → 1 Glyc). The five components detected in small amounts were: three disaccharides, ribosyl-glucose, xylosyl-glucose, and arabinosyl-glucose, and two trisaccharides both made up of fructose and glucose units in the ratio of 2:1.

ISSN:0008-4042    

DOI:10.1139/v68-008

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The hypothesis that the irradiation of unsaturated sultones gives the final products, the ketosulfonic esters, via a sulfene intermediate has been reexamined. In the case of sultone (4), it has been shown that, if such a species be an intermediate, it must have a lifetime, in cyclohexane solution, of less than 20 μs. The consequenes of this observation are discussed.The flashing of sultone (4) in methanol generates the enol of the keto ester end product (13) which decays with a half life of about 20 s

ISSN:0008-4042    

DOI:10.1139/v68-009

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A simple method was explored for the preparation of methyl 4,6-O-benzylidene-hex-2-enopyranosides. Methyl 2,3-anhydro-4,6-O-benzylidene-D-hexopyranosides were converted to diaxial iodohydrins using sodium iodide in acetone which contained sodium acetate and acetic acid. Treatment of the iodohydrins with either methane- orp-toluenesulfonyl chloride in refluxing pyridine yielded the 2,3-unsaturated derivative in excellent yield. The four isomers for methyl 4,6-O-benzylidene-D-hex-2-enopyranoside were thus prepared. The rotations of the anomeric pairs followed Hudson's rules of isorotation. Evidence is provided that, in the absence of strong destabilizing interactions in the product, the epoxide ring of one of the above-mentioned 2,3-anhydroglycosides is opened by lithium iodide in ether to form the iodohydrin as the lithium alkoxide in high yield. This observation provides an explanation for the reduction of methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside to 4,6-O-benzylidene-D-allal. Reaction of methyl 4,6-O-benzylidene-2-deoxy-2-iodo-α-D-idopyranoside with methyl lithium provided 4,6-O-benzylidene-D-gulal. The conformational properties of a number of the compounds prepared and of acetylated methyl pentopyranosides, as derived from their nuclear magnetic resonance parameters, are discussed with particular reference to the role that geminal coupling constants may play in the determination of configuration and conformational equilibria.

ISSN:0008-4042    

DOI:10.1139/v68-010

出版商:NRC Research Press    

年代:1968

数据来源: NRC