Table 1. Reaction Optimization^a.

entry	[Se]	acid	cat.	temp (°C)	time (h)	yield (%)b	ee (%)c
1	NPSS	HCl	4	rt	0.5	92	33(11d)
2	NPSS	PyHCl	4	rt	2	85	36(36d)
3	NPSS	PyHCl	5a	rt	2	82	46
4	NPSS	PyHCl	5b	rt	2	82	60
5	NPSS	PyHCl	5c	rt	2	88	64
6	NPSS	PyHCl	5d	rt	2	84	67
7	NPSS	PyHCl	5d	–30	48	67	72
8	NPSS	PyHCl	5d	–45	48	<5	nd
9e	NPSS	PyHCl	5d	–45	48	89	84
10e	NPASS	PyHCl	5d	–45	48	85	87
11e	NPASS	PyHCl	5d	–35	48	85	88
12e	NPASS	HCl	5d	–35	48	87	88

^aReactions conducted on 0.1 mmol scale.

^bIsolated yield of purified product.

^cEnantiomeric excess determined by HPLC analysis on commercial chiral columns.

^dee after 12 h.

^eHMPA(S) (10 mol%) was added.