Table 2. Concentration Effectsa.
entry | silane (equiv) | concb (M) | 5:6 (% yield) |
---|---|---|---|
1 | Et3SiH (2.0) | 0.125 | 58:42 (65) |
2 | Et3SiH (10.0) | 0.125 | 58:42 (32) |
3 | (i-Pr)3SiH (1.1) | 0.125 | 95:5 (57) |
4 | (i-Pr)3SiH (2.0) | 0.125 | 83:17 (89) |
5 | (i-Pr)3SiH (10.0) | 0.125 | 68:32 (93) |
6 | (i-Pr)3SiH (2.0) | 0.0125c | >98:2 (82) |
Ni(COD)2 (0.06 mmol), SIPr·HCl (0.05 mmol), and t-BuOK (0.05 mmol) were stirred with 2 mL of THF. Benzaldehyde (0.5 mmol), phenylpropyne (0.5 mmol), and silane were combined, diluted to a total volume of 2 mL, and added to the reaction mixture via syringe drive over 1 h at rt.
Concentration refers to the final molarity of the aldehyde and alkyne starting components.
The catalyst was prepared in 38 mL of THF.