Reactions of PhCOPdX(PPh3)2 (X=I, Cl) with alkylmetals under carbon monoxide; formation of α-diketones and α-hydroxyketones under stoichiometric and catalytic conditions

Article abstract of DOI:10.1016/0022-328X(88)80680-6

The reactions of PhCOPdX(PPh3)2 (Ia: X=I; Ib: X=Cl) with alkylmetals under carbon monoxide have been investigated.The reactivity of ethylmetals toward Ia was found to decrease in the order: Et2M (M=Zn, Cd, Hg) ca.EtZnCl ca.EtCu > EtmgBr ca.EtMnI ca.Et3Al > Et2AlCl > Et3B ca.Et4Sn (no reaction).In these reactions, the simple coupling product, PhCOEt (II) and /or the carbonylative coupling products IIIa-IIIc (IIIa: PhCOCOEt; IIIb: PhCEt(OH)COEt; IIIc PhCOCEt2(OH)) were formed depending on the nature of the ethylmetal.Et2Hg and Et3Al gave exclusively II.EtMgBr, EtCu, and EtZnCl gave both of II and III.EtMnI and Et2M (M=Zn, Cd) selectively gave III.The use of Ar2Zn (AR=Ph, p-Tol) in place of Et2Zn gave decreased yields of the carbonylative coupling products.The palladium complex Ib showed almost the same reactivity toward Et2Zn as Ia.Further to this palladium-catalyzed carbonylation reactions of PhCOCl with alkylmetals were examined.The reaction with Et2Zn catalyzed by PdCl2(PR3)2 (R=Ph, p-FC6H4) afforded III (mainly IIIb and IIIc, about 200percent/Pd).The combination of Pd(PPh3)4 and Et3Al more effactively afforded III (mainly acyloin-type reduced products, about 900percent/Pd).