27 1β-トシロキシ-4α,10β-ジメチル-cis-デカリン誘導体の加溶媒転位反応 : (±)-Bulnesolおよび(±)-Kessaneの合成

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Solvolytic rearrangement of some cis-decalin derivatives (3a, 3b and 30b) was examined. In equilibrium between steroidal and non-steroidal conformations the α-methyl group of these cis-decalin derivatives at C_4 was anticipated to contribute to predominant distribution of the former conformation, which is favorable for the rearrangement of these cis-decalins into hydroazulenes. The α-methyl group was introduced at the C_4-position of the acetoxy-octalone (4), as shown in Scheme 1, in the over-all yield of 78%. While the methylation product (10a) was hydrogenated on Pd-SrCO_3 to a mixture of the trans- and cis-decalones (11a and 12), in the ratio of 3: 1, the acetoxy-octalone (10b) exclusively afforded the corresponding cis-decalone (11b). The tosylate (3a) was solvolyzed in hot HOAc containing KOAc yielding a mixture of the hydroazulenic products (13 and 15) and the octalone (14) in the yield of 38 and 46%, respectively. The preparation of the tosylate (3b) and the mesylate (30b) are given in Scheme 3 and 4, respectively. Solvolysis of the tosylate (3b) under similar condition afforded (±)-bulnesol (1) and its isomer (25) in the ratio of 1: 1, and, on the other hand, the mesylate (30b) did (±)-kessane (2) (30% yield) and the bridged bicyclic product (32) (50% yield).
天然有機化合物討論会の論文
1970-10-01