The Meerwein-Ponndorf-Verley (MPV) reduction rates of eight representative mono-and bicyclic ketones Í--8 were established at 82.3 ± 0.4°under nonequilibrating conditions resembling preparative utilization of this reaction. Results obtained enabled, for the first time, a systematic comparison of substituent effects and stereochemistry in the vicinity of the CO group. The following reaction half-lives (ty2, min) for the pseudo-first-order disappearance of 0.213 M ketone in t-PrOH containing 0.252 M Al(0-f-Pr)3 were observed: 3-isothujone (7), 20.7; isomenthone (5), 21.9; menthone (4), 24.4; 3-thujone (8), 47.7; and camphor (6), 145.8. Reduction of cyclohexanone (2) and 2-methylcyclohexanone (3) was immeasurably rapid. Thus, in contrast to commonly held views, the MPV reduction of these ketones proceeds at a relatively high rate. The reduction of cyclopentanone (1) led to extensive by-product formation. Reduction of ketones 7 and 8 was studied in more detail at various ketone (0.483 and 0.0971 M) and Al(0-¿-Pr)8 (0.407, 0.147, and 0.0818 M) concentrations. It was found that the ratio of epimeric alcohols formed in the MPV reduction of ketones 7 and 8 was dependent on the concentration of ketone and Al(0-i-Pr)8, their ratio being constant. In dilute solution the preponderance of cis alcohol was more pronounced than at higher concentration. The reduction rate of thujone 8 was also measured at 100 ± 0.5°in sec-BuOH with Al(0-sec-Bu)8 as catalyst. The reduction was more stereospecific than with Al(0-f-Pr)3 under comparable conditions. Various aspects of these findings are briefly discussed.

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Conditions necessary for the formation of the (+)3-thujone bisulfite adduct 1a and its utilization for the isolation of pure (+)-thujone have been established.

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A series of novel, representatively substituted amides of thujic acid were prepared and screened for insect repellent and attractant potential. In repel-lency tests the N,N-diethylamide was the most potent compound, surpassing the activity of the standard repellents dimethyl phthalate and fencholic acid. In contrast, the N-monoethylamide displayed attractant activity.