Table 3.

Alkynylation of α,β-Unsaturated Aldehydes.

entry	R1	R2	R3	R4	yield[a]	ee[b]
1	H	Ph	H	TMS	89%	91%
2[c]	H	Me	H	TMS	89%	39%
3	H	−C6H13	H	TMS	90%	36%
4	H	iPr	H	TMS	100%	94%
5	Me	H	H	TMS	74%	91%
6	Me	Et	H	TMS	67%	87%
7	−(CH2)4−		H	TMS	81%	90%
8	H	H	H	−(CH2)2OTBS	55%	90%
9	H	Ph	Ph	TMS	80%	76%
10	Br	−C6H13	H	TMS	66%[d]	91%
11	Br	Ph	H	TMS	68%	95%
12	Me	−CO2Et	H	TMS	75%	86%
13	H	Ph	H	BDMS	100%	73%
14	H	Ph	H	−CH(OEt)2	85%	82%
15	H	iPr	H	−CH(OEt)2	85%	87%
16	H	Ph	H	−C6H13	100%	77%

^[a]Isolated yield. Reactions performed on a 0.325 mmol scale.

^[b]Enantiomeric excess determined by chiral HPLC analysis.

^[c]Reaction performed with 2.7 equiv alkyne and 2.6 equiv Me₂Zn.

^[d]14% of the methyl addition side product was also isolated.