Table 2.
Trends in Diastereoselectivity
| ||||
|---|---|---|---|---|
| Entry | alkyl group | catalysis trans da (%)[a] | background trans de (%)[a] | trans Δdc (%)[a] |
| 1 | methyl | 100 (>95) | 74 (69) | 26 (26) |
| 2 | ethyl | 2 (−9) | −26 (−26) | 28 (17) |
| 3 | propyl | −4 (0) | −38 (−33) | 34 (33) |
| 4 | allyl | 36 (46) | −30 (−29) | 66 (75) |
| 5[b] | octyl | −31 (nd) | −34 (−29) | 3 (nd) |
| 6 | benzyl | −53 (−31) | −49 (−43) | −4 (12) |
| 7 [b] | cyclopropyl | 34 (nd) | 49 (53) | −15 (nd) |
| 8 | phenyl | 5 (0) | 7 (0) | −2 (0) |
[a]
Diastereomeric excess in the parenthesis was determined by 1H NMR of the crude reaction mixtures.
[b]
Diastereomeric excess could not be determined from the crude reaction mixture by 1H NMR due to overlapping signals.