Table 2.
| ||||||
---|---|---|---|---|---|---|
entry | R | R1 | R2 | yield 7(%)a | yield11(%)a | Ratio7:10b |
a | H | H | CH3 | 40 | 56 | 1:1.2 |
b | H | H | CH2OTBS | 22 | 29 | 1.2:1 |
c | H | H | CH2CH2OTBS | 52 | 43 | 1.5:1 |
d | H | H | t-Bu | 57 | 20 | 2.7:1 |
e | Ph | H | CH3 | 40 | 30 | 1:1.2 |
f | CH3 | H | CH3 | 36 | 36 | 1:1.3 |
g | H | Ph | CH3 | - - | 35 (10g) | 1:1.1 |
h | –(CH2)4– | CH3 | 36 | 51 | 1:1.4 | |
i | –(CH2)3– | CH3 | - - | 40 (10i) | 1:1.5 |
Yield for chromatographically pure, characterized material.
Ratio by 1H NMR analysis of the crude thermoslyate.