Table 3.

Catalytic Carbonylative Conjugate Addition of Et₂Zn to α,β-Unsaturated Aldehydes.^a

entry	substrate	product	R3SiCl	% yield
				L:PPh3	L:PCy3
1			Et3SiCl	78	69
2			Et3SiCl	41	39
3			Et3SiCl	90b	72b
4			Ph3SiCl	63	60
5			Ph3SiCl	68c
6			Et3SiCl	N.R.

^aReaction with 1.3 equiv Et₂Zn, 2.3 equiv TMSCl, 1 atm CO; 4 h for entries 1 and 2; 20 h for entries 3 and 4; 24 h for entries 5 and 6. Subseqeunt to reaction, the mixture was quenched at 0 °C with acetic acid (1.5 equiv) and TBAF (1.5 equiv) for 10 minutes and then treated with saturated Na₂CO₃.

^bQuench (footnote a) was omitted from this reaction.

^cA 2:1 mixture of olefin isomers was obtained.