Driman-8,11-diol synthesis

Recently, we have elaborated an alternative method of the drimenol (2) synthesis from the hydroxy ketone (63) of preparative value [49]. In the article [46] it was shown that on oxidation of the hydroxy ketone (63) with trifluoroperacetic acid under certain conditions, the 11-monoacetate of drimane-8a,l 1-diol (42) is obtained in the quantitative yield. On treatment of the compound (42) at room temperature with 30% solution of concentrated sulphuric acid in ethanol by using 10 ml of this solution per 1 g of the compound (42), the crystalline drimenol (2) was obtained in 56% yield, which could be purified by recrystallisation from n-hexane [49] (Scheme 10). In such a way, at stage e) selective dehydration and transesterification of the hydroxy acetate (42) took place. 

Drimane-8a,l 1-diol (41) and its 11-monoacetate (42) are suitable starting compounds for the synthesis of a series of drimanes and not only of them. Only the diol (41) was found in natural sources and was isolated from tobacco [51] and from a special gland of African elephant [52], Data about the synthesis of these compounds from the ambreinolide [39] and of the hydroxy acetate (42) from the sclareol (3) have been already reported [42]. Barrero et al. [42] showed also that if the reduction of the ozonolysis product of the mixture of esters (54) is done with LiAlFE instead of NaBH4, the diol (41) is obtained in a 95% yield (Scheme 11). 

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