Table 4.
Diastereoselective Generation of (E)-Di- and Trisubstituted Allylic Alcohols and Dienyols.
 | |||||
|---|---|---|---|---|---|
| entry | PG | alkyne | yield (%) | dra | major productb |
| 1 | TBS |
|
20 | 1:1.5c |
|
| 2 |
|
82 | >20:1 |
|
|
| 3 |
|
54 | 17:1 |
|
|
| 4 |
|
82 | 11:1 |
|
|
| 5 |
|
72 | >20:1 |
|
|
| 6 |
|
92 | 10:1 |
|
|
| 7 |
|
70 | >20:1 |
|
|
| 8 |
|
85 | >20:1 |
|
|
| 9 | TES |
|
93 | >20:1 |
|
a
dr determined by 1H NMR of the crude product and refers to the ratio of Cram-chelation:Felkin addition products.
b
Absolute configurations of alcohols were determined by modified Mosher ester analysis.
c
The yield and dr correspond to the reaction without EtZnCl.