Verbanyl acetate

The cyclic ether (219) was converted into (220), which underwent rearrangement to (221) in a manner analogous to the celebrated norcaradiene ring-walk stereochemical analysis of the rearrangement indicated predominant inversion of configuration for both the photolytic and thermal processes and so symmetry considerations of the Woodward-Hoffman type may not be relevant to these (or at least the thermal) processes.559 Esters of pinocarveol were converted into myrtenyl compounds by CuOAc.560 cis- and rrans-Verbenyl and verbanyl acetates,561 562 related compounds563 and 2-methylverbanone564 have been synthesized for evaluation as attractants for cockroaches. 

Verbanone and its derivatives are normally made by oxidation of a-pinene [usually (+ )-116] when Takayanagi and Nishino required (— )-trans-verbanone (822), they used a synthetic procedure starting from (+ )-apoverbenone [(+ )-823] accessible from the ( —)-p-pinene series. The Wharton reaction (hydrazine hydrate) with the (trons)-epoxide of 823 yields 824, which can be oxidized to (— )-apoverbenone [( —)-823], from which 822 was obtained by reaction with lithium dimethyl cuprate. [This work was actually to prepare verbanyl acetates, the (l/ ,2/ ,5/ )-series of which notably ( + )-825 is active as pheromone mimics in the cockroach Periplaneta americana, while the (15,2S,5S)-series from 822 are inactive. 

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