New aspects of the carbonylation of allylpalladium complexes

Abstract

The carbonylation of (~3-allyl)palladium(II) chloride dimer in the presence of an excess of ylide, such as Ph,PC(H)COR (R = Me or Ph) (Pd: ylide = 1: 5) in MeOH or EtOH, at a CO pressure of 4 atm at room temperature occurs with reduction of the palladium(U) complex to palladium metal and with formation of the corresponding alkyl 3-butenoate with a high yield. The ylide does not give rise to any carbonylation product. When the carbonylation is carried out in the presence of PPh, (Pd: PPh, = 1: 2-3), there is also formation of the unsaturated ester, although in lesser amount, together with [Pd,(PPh,),(CO),](n E 3 or 4) or [Pd(PPh,),(CO)] and trans-[Pd(PPh,),(COOR)CI] (R = Me or Et). These products also form when the carbonylation is carried out in the presence of NJZt, or PrCOONa, in place of the ylide, and of PPh,.It has also been found that [Pd(PPh3),C12] reacts in MeOH or EtOH at a CO pressure of 4 atm at ambient temperature in the presence of an excess of ylide to give the corresponding carbalkoxy complex trans-[Pd(PPh3)JCOOR)C1]. These findings suggest that the ylide probably promotes formation of carbalkoxy species, as do NEt, or PrCOONa because the ylide can behave as a base (pK, = 7). They are strong support for the suggestion that the carbonylation of (allyl)palladium complexes occurs via a (carbalkoxy)palladium species.

Palladium(II)‐catalyzed catalytic aminocarbonylation and alkoxycarbonylation of terminal alkynes: regioselectivity controlled by the nucleophiles

“…This method provides advantages in terms of both catalytic activity and regioselectivity compared with the systems described in the literature. It seems that the alkoxy mechanism is playing a minor role in this process because the initial formation of palladium carboalkoxy decreased with the increase in number of carbons of alcohols 25–27…”

Palladium carbonyl complexes

“…38 This complex has also been synthesised by Zhir-Lebed' et al 39 The formation of complex 1 has been noted in the carbonylation of [(Z 3 -allyl)PdCl] 2 in the presence of PPh 3 in solution in methanol or ethanol (P CO = 4 atm; 293 K). 40 The divalent palladium acetate complex (PPh 3 ) 2 Pd(OAc) 2 is not reduced by carbon monoxide in methanol under mild conditions. 41 Only at 323 K and a CO pressure of 20 ± 50 atm is Pd(+2) reduced to Pd(0) with formation of a mixture of complexes 1 and 3.…”

CO–ethene copolymerisation catalysed by [PdCl2(PPh3)2]/PPh3/HCl in MeOH

“…Moreover, the light products that have been detected by GC do not have ester-ester end groups. Therefore, it is unlikely that catalysis initiates from a Pd-OCH 3 [41] Hydride (1) that initiates the catalysis can form from the precursor (A) by interaction of H 2 O and CO with the metal centre, through a reaction closely related to the water gas shift reaction (WGSR) [42][43][44][45][46][47].…”