SELECTIVE BROMINATIVE CYCLIZATION OF POLYENES ASSISTED BY ACETONITRILE. APPLICATION TO THE SYNTHESIS OF ACORATRIENE

Reaction of polyenes (4a, b) with 2,4,4,6-tetrabromocyclohexa-2,5-dienone at –20 °C in the presence of MeCN and subsequent quenching with water gives monocyclic amides (8a, b) and (9a, b), while the cycloalkene (7a, b) was formed during the reaction at room temperature; acoratriene (12) was elaborated from (7b)via a ring contraction product (10b).