Novel tandem ring-opening/ring-closing metathesis reactions of functionalized cyclohexenoids derived from (-)-α-pinene

The cyclohexenone (+)-2, readily obtained from (-)-α -pinene 1 was elaborated to (+)-3 in an attempt to construct the AB rings of taxoids employing the ring-closure metathesis (RCM) reaction as the key step. In the event, a novel ring-opening/ring-closing metathesis reaction was encountered in the relatively strain free cyclohexenyl ring of (+)-3