Table 1. Optimization of Wittig Reaction with Aldehyde 1a.
entry | PR3 | X | temp (°C) | time (h) | yield of 2aa (%) | E/Zb |
---|---|---|---|---|---|---|
1 | PMe3 | 1.4 | 23 | 48 | 76 | 4:3 |
2 | PEt3 | 1.4 | 23 | 48 | 80 | 4:3 |
3 | PBu3 | 1.4 | 23 | 48 | 72 | 4:3 |
4 | PPh3 | 1.4 | 23 | 48 | 0 | |
5 | P(OMe)3 | 1.4 | 23 | 48 | 0 | |
6 | PMe3 | 1.2 | 23 | 48 | 95 | 3:1 |
7 | PEt3 | 1.2 | 23 | 48 | 99 | 3:1 |
8 | PBu3 | 1.2 | 23 | 48 | 91 | 3:1 |
9 | PEt3 | 1.2 | 65 | 8 | 97 | 3:1 |
Isolated yield.
E/Z values were calculated from the ratio of the integrals of the allylic methylenes in the 1H NMR spectra.