Table 9.

Optimization of the hydrolytic nitrile reduction.

Entry	Conditions	Result (Stage 1)	[H-] source	Yield (83, 2 steps)
1	Cp2Zr(H)Cl (2.0 equiv.), THF, 23 °C	trace conv.	–	–
2	K-selectride (2.0 equiv.), THF, 0 °C	trace conv.	–	–
3	DIBAL (2.3 equiv.), DCM, −78 °C	complex mixture	–	–
4	DIBAL-n-BuLi (2.4 equiv.), THF, DCM, 0 °C	SM + decomposition	–	–
5	AlMe3 (1.0 eq.), DCM, 0 °C, then DIBAL (2.0 equiv.), −78 °C	–	DIBAL	29% (41% brsm)
6	AlMe3 (1.0 equiv.), DCM, −78 °C then BF3•OEt2 (1.0 equiv.), DIBAL (2.5 equiv.), −78 °C	trace conv.	–	–
7	BEt3 (1.0 equiv.), DCM, 0 °C then DIBAL (2.5 equiv.), −78 °C	trace conv.	–	–
8	Et3Al (1.0 equiv.), DCM, 0 °C then DIBAL (2.5 equiv.), −78 °C	85% mass recovery	NaBH4	46% (58% brsm)