Condition screening for hydroboration of phenylacetylene with HBpin^a.

Entry	Catalyst	Additive	Solvent	Yield of β-(E)-3ab (%)
1	1	KOtBu	THF	65
2	2	KOtBu	THF	5
3	1	None	THF	<5
4	None	KOtBu	THF	<5
5	1	NaOtBu	THF	52
6	1	LiOtBu	THF	46
7	1	KOMe	THF	30
8	1	K2CO3	THF	<5
9	1	LiNTf2	THF	<5
10	1	NaHBEt3	THF	42
11	1	KHBEt3	THF	50
12	1	KOtBu	Toluene	<5
13	1	KOtBu	Et2O	<5
14c	1	KOtBu	DMSO	78
15	1	KOtBu	Neat	82
16d	1	KOtBu	Neat	83
17e	1	KOtBu	Neat	Trace

^aConditions: phenylacetylene (0.5 mmol), pinacolborane (0.6 mmol), 1 (0.2 mol% based on Fe₃(L)₄ unit), additive (1 mol%) and solvent (0.5 mL), rt, N₂, 16 h. Other isomeric products were detected with <5% yield unless otherwise stated.

^bDetermined by GC analysis with hexamethylbenzene as an internal standard.

^cRegioisomer α-3a was detected in 8% yield.

^d1 mol% of 1 was used.

^eReaction run in the air. LiNTf₂: lithium bis(trifluoromethane)sulfonimidate.