Entry

[H]

Solvent

Temp. [˚C]

Time [hours]

^aYield of 21%

1

NaBH₄

MeOH

0 ? r.t.

2

98

2

NaBH₄

MeOH

−10

24

99

3

N(CH₃)₄BH₄

MeOH

−10

24

94

4

N(CH₃)₄BH₄

MeOH

0 ? r.t.

7

88