Reactions of organometallic compounds catalyzed by complexes of transition metals Communication 5. Organomagnesium, -zinc, -cadmium, and -aluminum compounds in allyldemetallation reactions catalyzed by palladium complexes

Abstract

1. Reactions of organometallic compounds RM (R=Ph, p-MeC6H4, p-BrC6H4, p-MeOC6H4, p-Me2NC6H4, PhCH2, PhCH=CH, 9-fluorenyl, 2-thienyl, PhC≡C; M=MgBr, ZnCl, CdBr, AlCl2) with CH2=CHCH2X (X = Br, OAc, OPh,+NEt3) catalyzedby Pd(PPh3)4 and (λ3-C3H5PdCl)2 in THF have been studied. The influence has been investigated of the nature of metal M, of the organic radical R, and of the leaving group X on the rate of allyl-demetallation and on the yield of products RCH2CH=CH2 and R2. 2. The reactions of RMgBr (R=Ph, p-MeC6H4, p-BrC6H4, PhCH2, 9-fluorenyl, 2-thienyl) with CH2=CHCH2Br catalyzed by Pd(PPh3)4 proceeded significantly more rapidly and selectively than in the absence of palladium catalyst which made it possible to obtain the corresponding products of allyldemetallation under mild conditions and in high yield. 3. The main possibility of allyldemetallation of Reformatsky reagents has been shown for the first time in the example of the reaction of BrZnCH2CO2Et with CH2=CHCH2Br catalyzed by (λ3-C3H5PdCl)2 and leading to the preparation of CH2=CHCH2CO2Et. The reaction is a convenient method for introducing the allyl group into theα-position of esters.