Benzonilidene compounds (2 and 30) derived from abietic acid (1), can be regarded as a kind of dienone and aroused our interest in its reactivity. It have been found that the benzonilidenes behave in completely different manner (I〜III type rearrangement) according to the variation of the reagent and their structures. 1). I-Type Rearrangement. (2)(c.H_2SO_4-Ac_2O, 63% Y.) ⇄ (3)(c.H_2SO_4, quant. Y.). The electrophilic reagent could be attacked successfully to C_1-position to give (4) and (5) through the rearrangement. 1-a application). Synthesis of Teideadiol (5→6). 1-b application). Transformation to Grayanotoxin Skeleton (5→11). 2). II-Type Rearrangement. (2)(AlCl_3)→(15)(51% Y.)+(16)(5% Y.)+(2)(15% Y.). 3). III-Type Rearrangement. (30)(c.H_2SO_4-Ac_2O)→(31)(82% Y.).
