FUMINORI AKIYAMA, and NOEMI CHUAQUI-OFFERMANNS. Can. J. Chem. 59,705 (1981).The I3C chemical shifts in a variety of aldimines and in both acyclic and cyclic ketimines have been examined. A comparison of the shieldings at the a carbons in syn versus anti stereoisomers shows a consistent upfield shift of 8-11 ppm in the syn isomer. The greater magnitude found in imines vs. oximes or hydrazones is a clear indication of a steric origin for the differential shieldings. The shifts in the imines of cyclohexanones exhibited stereochemically dependent effects of methyl substitution, very similar to those in analogous oxime and hydrazone derivatives. Chemical shift differences in the syn isomers of the a-phenethylimines of chiral aldimines and ketimines allow a facile measurement of diastereomer ratios for such compounds.ROBERT R. FRASER, JACQUES BANVILLE, FUMINORI AKIYAMA et NOEMI CHUAQUI-OFFERMANNS. Can. J. Chem. 59,705 (1981). On a examine les deplacements chimiques du I3C de diverses aldimines et des cetimines acycliques et cycliques. En comparant le blindage au niveau des carbones en positions a des stCrCoisomkres syn et anti, on constante un dtplacement vers les champs forts de 8-1 1 ppm en faveur de I'isomere syn. La valeur plus forte observee pour les imines par rapport icelle des oximes ou des hydrazones est une nette indication de I'origine sttrique des blindages differentiels. Les deplacements observes dans les imines de cyclohexanones ont des effets qui dependent stereochimiquement de la substitution par les methyles et qui sont trks semblables a ceux des derives analogues d'oximes et d'hydrazones. Les differences de deplacement chimique des isomkres syn desa-phenethylimines d'aldimines et de cetimines chirales permettent de mesurer facilement les rapports de diastereoisomkres dans de tels composes.[Traduit par le journal]The 13C spectral characteristics of aldehydes and ketones have been thoroughly studied (1, 2) and more recently many of their carbonyl derivatives including oximes (3-9, hydrazones (5, 6), and oxime ethers (6) have received considerable attention. Another class of nitrogen-containing carbonyl derivatives which has not been studied to any significant extent is the imines, data on only a few aryl(7) and a few anti aldimine derivatives (8) having been reported. During the course of our studies on the alkylation of ketimines (9, 10) and aldimines (11, 12) we have had the opportunity to record a large number of spectra of both the syn and anti isomers. In this paper we wish to describe the spectral characteristics of a number of representative examples in order to demonstrate the capability of 13C nmr to reveal both configurational and conformational information for this class of compounds. In addition, the comparison of configurational effects with those previously observed in other species provides clear evidence for the dominance of steric factors in causing the large --differential syn-anti shifts. ExperimentalThe imines described herein have all been synthesized either from the parent ketone...

2-Isopropyl-5-methyl-1-cyclohexenyl alkyl sulfides were obtained in about a 60% yield by the reaction of 2-isopropyl-5-methylcyclohexanone with thioacetals or thiols in the presence of aluminum chloride. 1-Cycloalkenyl ethyl sulfides, (Remark: Graphics omitted.) (n=4, 5, or 6, R=H or alkyl) were obtained in good yields by the reaction of cycloalkanones with ethanethiol in the presence of diphosphorus pentaoxide. However, an attempt to apply this method to acyclic vinyl sulfides was unsuccessful.

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The acylations of l-menthol with p-substituted benzoyl-and substituted acetyl chlorides were carried out, and it was found that the electron-releasing substituents accelerate the reaction rate in chloroform even though the reaction is completely of the SN2 type. This result is interpreted in relation to the low isokinetic temperature, the reaction itself being carried out above that temperature. Such a phenomenon is discussed in terms of the configurational and the solvent effects on the entropy of activation.