Abstract
An attractive feature of the allylic coupling reaction catalyzed by a transition metal is the possibility to create a secondary carbon at an allylic position. To examine this possibility, we have developed reactive borates of types 2-4 (eq 2), which react with secondary allylic carbonates and acetates efficiently in the presence of a nickel catalyst. Regarding reactivity, 4 is the most reactive reagent. In addition, it is possible to replace the Me or butanediol-ligands or the Li counter cation by others in order to raise the reactivity of 4 for specific substrates and purpose. This idea was successful to create new reagents 5, 6, and 14 : 5 for reaction with monoacetate 9 (eq 3) and aryl mesylates 12 (eq 4); 6, reagents possessing a carbonyl group (eq 16, Fig.5); 14 for reaction with sterically congested cis bromides 13 (eq 5). By using these reactions, synthesis of prostaglandins, aristeromycin, brefeldin A, 10, 11-dihydroleukotriene B4, korormicin was accomplished successfully (Fig.1 and 2).
