Table 1. Optimization studies.

#	Deviations from stand. cond.	Y. of 2a,a (%)
1	None	99
2	InBr/LiBr (1.2 equiv.)	97
3	Heat at 60 °C	80
4	50 °C + ultrasound	90
5b	20 °C	40
6	Air atmosphere	71
7b	DME as solvent	95
8b	MeCN as solvent	77
9b	THF as solvent	75
10	LiCl (1.5 equiv.) instead of LiBr	35
11	No LiBr	48
12	In (1.5 equiv.) instead of InBr	41

^aDetermined by ¹H NMR with 1,3,5-trioxane as an internal standard.

^b16 h.