Exploration and optimizationa.
| |||||
|---|---|---|---|---|---|
| Entry | Derivation from standard conditions | Yieldb (%) | drc (endo : exo) | Dc (%) | eec (%) |
| 1 | None | 92 | >20 : 1 | 96 | 99 |
| 2 | Without 3 Å MS | 82 | 15 : 1 | 96 | 99 |
| 3 | D2O (7 equiv.) instead of D2O (28 equiv.) | 94 | >20 : 1 | 78 | 99 |
| 4 | D2O (14 equiv.) instead of D2O (28 equiv.) | 93 | >20 : 1 | 91 | 99 |
| 5 | D2O (56 equiv.) instead of D2O (28 equiv.) | 92 | >20 : 1 | 97 | 99 |
| 6d | MeOD as solvent | 85 | 3 : 1 | 96 | 96 |
| 7d | V DCM : VMeOD = 10 : 1 as the solvent | 80 | 17 : 1 | 95 | 99 |
a
All reactions were carried out with 0.2 mmol of 1a, 0.3 mmol of 2a, and 0.2 mmol of Et3N in 2 mL of DCM and 0.1 mL of D2O for 3–6 h, see the ESI for details.
b
Yields refer to isolated yields of deuterated products.
c
The dr value was determined by crude 1H NMR. D refers to D-incorporation percentages based on the calculations described in the ESI. The ee value was determined by HPLC analysis.
d
Without 3 Å MS.