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. Author manuscript; available in PMC: 2009 Jun 23.
Published in final edited form as: J Org Chem. 2008 May 1;73(11):4017–4026. doi: 10.1021/jo800204n

Table 4.

Asymmetric Reduction of 25 under Different Reaction Conditions

graphic file with name nihms100434f10.jpg
entry cat 10 (equiv) BH3–THF (equiv)a T (°C) solvent time (h) isolated yield (%)b ee (%)c
1 0.1 5.0 0 THF 72 50 8
2 1.0 5.0 0 THF 96 46 13
3 1.0 2.0 10 dioxane 72 57 60
4 1.0 3.0 10 dioxane 48 71 57
5 1.0 4.0 10 dioxane 48 79 73
6 0.3 5.0 10 dioxane 72 34 4d
7 1.0 2.0 10 dioxane 48 73 54e
a

Stabilized with NaBH4.

b

Isolated yield of amide.

c

Determined by GC of acetyl derivatives on a chiral column (CP-Chirasil-Dex-CB).

d

Triethyl borane (1.0 equiv) was added.

e

BF3 (1.0 equiv) was added.