Development of modified Pauson-Khand reactions with ethylene and utilisation in the total synthesis of (+)-taylorione

Two complementary Pauson-Khand annulation protocols for use with the gaseous alkene, ethylene, are described These N-oxide promoted reactions (10 examples) are shown to proceed under both mild autoclave conditions or, more conveniently, at atmospheric pressure. The developed methodology has been utilised as the key transformation in the total synthesis of the sesquiterpene (+)-taylorione which has been realised in a good overall yield from readily available (+)-2-carene. Copyright (C) 1996 Elsevier Science Ltd