摘要:

Manool and agathadiol cyclize in formic acid to the 13-epimeric pimara-8,15-dienes and 14α-hydroxyhibane derivatives. The mechanistic and biosynthetic implications of these results are discussed in relation to other work involving cations in tetracyclic diterpenes. The nuclear magnetic resonance spectra of relevant tricyclic and tetracyclic diterpenes are documented.

ISSN:0008-4042    

DOI:10.1139/v68-186

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Condensation polymers were prepared starting from difunctional silicon-containing carboxylic acids or diols. Dimethyl bis(p-carboxymethylphenyl)silane was condensed with various diols to yield polyesters and with various diamines and diisocyanates to yield polyamides. Dimethyl bis(p-carboxymethylphenyl)silane and dimethyl bis(p-hydroxymethylphenyl)silane were condensed with dicarboxylic acids to yield polyesters, with diisocyanates to yield polyurethanes, and with ethyl chloroformate to yield a polycarbonate. Some of the properties of the polymers were compared with those of the corresponding polymers prepared from dimethyl bis(p-carboxyphenyl)silane.

ISSN:0008-4042    

DOI:10.1139/v68-187

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Nuclear magnetic resonance data for a series of 2′-halogeno and 3′-halogeno pyrimidine nucleosides are presented. Using a combination of proton–proton and proton–fluorine couplings vs. dihedral angle values 2′-deoxy-2′-fluorouridine is proposed to have an envelope conformation with C–3′endo, and 1-(3-deoxy-3-fluoro-β-D-arabinofuranosyl)uracil proposed to have a twist conformation with O-ringendoand C–1′exo. Correlations between substituent electronegativity and both vicinal coupling constants and internal chemical shifts are discussed.Syntheses of several new 2′-halogeno and 3′-halogeno nucleosides are described.

ISSN:0008-4042    

DOI:10.1139/v68-188

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The distribution of products in the nitration of a series of eight substituted acetanilides has been studied using differing nitrating agents.With mixed nitric and sulfuric acids, attackparato the acetamido group is favored, while with acetyl nitrate or nitronium tetrafluoroborate, predominantorthosubstitution occurs. It is suggested thatorthosubstitution results from SN2 displacement by a pair of substituent electrons (on nitrogen or carbonyl oxygen) on the species NO2X (X = BF4or OAc), leading to formation of the most readily accessible σ complex, while theparasubstitution favored in mixed acids results from substitution in the conjugate acid of acetanilide.Nitroacetanilides follow an unusual path with acetyl nitrate, yielding the corresponding dinitrobenzene in addition to the expected dinitroacetanilides.Nuclear magnetic resonance spectroscopy efficiently demonstrates the structures of the reaction products, and reveals the preferred intramolecularly hydrogen-bonded conformation ofortho-nitroacetanilides.

ISSN:0008-4042    

DOI:10.1139/v68-189

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

p,p′-Disubstituted azocumenes were prepared from the requisitep-substituted cumylamines,p-XC6H4C(CH3)2NH2, X = CH3, CH3CH2, (CH3)2CH, (CH3)3C, or Br, by treatment with iodine pentafluoride. The major products from thermal decomposition were dicumyls, along with minor amounts of cumenes and α-methylstyrenes. Syntheses of the corresponding authentic materials are described.

ISSN:0008-4042    

DOI:10.1139/v68-190

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The Bamford–Stevens reaction ofo-phthalaldehyde di-p-toluenesulfonylhydrazone givesN-(3,4-dihydrophthalazinyl)p-tolylsulfone. The product is synthesized by an independent method.

ISSN:0008-4042    

DOI:10.1139/v68-191

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The effect of solvents and various amines on the dimerization of isoprene with alkali-metal naphthalene, and the preparation of a new terpenic carboxylic acid, 4,8-dimethyl-3,7-nonadienic acid, by carboxylation of isoprene are described. Tetrahydrofuran, and the 50/50 (v/v) mixture of tetrahydrofuran and dimethyl sulfoxide each gave 40% of isoprene dimer. Sodium naphthalene in tetrahydrofuran solution containing a small amount oft-butylamine is active for the reductive dimerization of isoprene.

ISSN:0008-4042    

DOI:10.1139/v68-192

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Phenoxyphenyl acetate and several 4′-substituted derivatives were synthesized and their rates of saponification determined. The nature of the 4′-substituent was correlated with the rate of saponification by means of the Hammett equation.

ISSN:0008-4042    

DOI:10.1139/v68-193

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The electron spin resonance spectra of pyrene, dissolved in sulfur dioxide – boron trifluoride, are investigated. Two different spectra can be obtained, depending on the experimental conditions, and are ascribed to the monomeric and dimeric hydrocarbon radical cations.

ISSN:0008-4042    

DOI:10.1139/v68-194

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

4-Methyl- and 4-ethyl-6,7-dimethoxyisoquinolines have been synthesized by base-induced alkylation of homoveratronitrile, hydrogenation,N-formylation of the resultant amines, phosphorus pentoxide-induced cyclization and palladium-catalyzed dehydrogenation. Homoveratronitrile underwent self-condensation to the dimer, 2,4-bis-(3,4-dimethoxyphenyl-)3-aminocrotonitrile, under the influence of potassiumt-butoxide. 4-Carbomethoxy-6,7-dimethoxyisoquinoline was synthesized by the following sequence of reactions: base-catalyzed condensation of homoveratronitrile with ethyl formate, acid-induced interaction with urethane, pyrolytic cyclization, phosphorus oxychloride treatment, palladium-catalyzed hydrogenolysis, and hydrolysis and esterification of the resultant 4-cyano-6,7-dimethoxyisoquinoline.

ISSN:0008-4042    

DOI:10.1139/v68-195

出版商:NRC Research Press    

年代:1968

数据来源: NRC