. 2018 Nov 19;23(11):3023. doi: 10.3390/molecules23113023

Table 2.

Optimization of the acetylenylation conditions for N,O-acetal TMS ethers.

graphic file with name molecules-23-03023-i002.jpg

Entry ^a	M	Additive	Lewis acid	Solvent	Yield ^b
1	MgBr	CuBr·SMe₂	BF₃·OEt₂	THF	ND ^c
2	MgBr		BF₃·OEt₂	THF	ND ^c
3	Li		BF₃·OEt₂	THF	ND ^c
4	SiMe₃		BF₃·OEt₂	CH₂Cl₂	ND ^c
5	n-Bu₃Sn		BF₃·OEt₂	CH₂Cl₂	58
6	n-Bu₃Sn		BF₃·OEt₂	THF	ND ^c
7	n-Bu₃Sn		BF₃·OEt₂	PhCH₃	37
8	n-Bu₃Sn		BF₃·OEt₂	Et₂O	29
9	n-Bu₃Sn		SnCl₄	CH₂Cl₂	ND ^c
10	n-Bu₃Sn		TiCl₄	CH₂Cl₂	ND ^c
11	n-Bu₃Sn		TMSOTf	CH₂Cl₂	46

^a All reactions were performed using 0.2 mmol of 2d in dry solvent (2 mL) by adding the additive (if any) at −50 °C. The nucleophile was then added at the same temperature followed by the addition of BF₃·OEt₂ at −78 °C and stirring for 1 h. The reaction mixture was slowly warmed to r.t. over 2 h before quenching with Et₃N. ^b Isolated yields. ^c Not detected.