Table 2. Assessment of C2 stereochemistry of 36, 9, 10, 76, and 39.
entry | starting material | steps | overall yield | product [(+)- or (−)-75] |
---|---|---|---|---|
1) LAH | ||||
1 | 2) TBSCl, Imidazole | 76% | (+)-(R)-75 | |
1) BH3·SMe2, THF | ||||
2 | 2) TBSCl, Imidazole | 84% | (+)-(R)-75 | |
3) CAN | ||||
1) BH3·SMe2, THF | ||||
3 | 2) TBSCl, Imidazole | 68% | (+)-(R)-75 | |
3) CAN | ||||
1) DIBAL, −78 °C | ||||
4 | 2) TBSCl, Imidazole | 56% | (+)-(R)-75 | |
3) CAN | ||||
1) DIBAL, −78 °C | ||||
5 | 2) TBSCl, Imidazole | 61% | (−)-(S)-75 | |
3) CAN |