Table 2.

Examination of the reaction conditions using a pilot reaction.

Entry	Solvent	Temp.	Additive (equiv)	Yield (%)a
				3Bh	4Bh
1	DMF	0 °C → rt	none	0	0
2	DMF	80 °C	none	0	8
3	DME	0 °C → rt	none	17	0
4	THF	0 °C → rt	none	20	0
5	THF	rt	ZnCl2 (1.2)	30	0
6	THF	rt	ZnCl2 (10 mol %)	19	0
7	THF	rt	InBr3 (1.2)	0	0
8	THF	rt	Al(OiPr)3 (1.2)	0	9
9	THF	rt	BF3·Et2O (1.2)	46	0

^aIsolated yield.