Scope of syn-selective Michael addition.

Entry	1	2: R2	Time (d)	syn-5	Yielda (%)	drb	eec (%)
1	1a	2a: 4-ClC6H4	7	syn-5a	76	7 : 1	93
2	1a	2b: 3-ClC6H4	8	syn-5b	79	7 : 1	93
3	1a	2c: 2-FC6H4	7	syn-5c	73	9 : 1	95
4	1a	2d: Ph	9	syn-5d	85	9 : 1	96
5	1a	2e: 4-MeC6H4	10	syn-5e	79	9 : 1	96
6	1a	2f: 2-naphthyl	7	syn-5f	81	8 : 1	93
7	1a	2g: 2-thienyl	7	syn-5g	85	10 : 1	96
8	1a	2h: (E)-PhCH CH	8	syn-5h	76	15 : 1	94
9	1a	2i: (E)-4-BrC6H4CH CH	5	syn-5i	70	13 : 1	93
10	1a	2j: (E)-3-FC6H4CH CH	6	syn-5j	68	12 : 1	92
11	1a	2k: (E)-2-FC6H4CH CH	8	syn-5k	81	12 : 1	94
12	1a	2l: (E)-2-MeC6H4CH CH	9	syn-5l	80	13 : 1	94
13d	1b	2h: (E)-PhCH CH	4	syn-5m	88	12 : 1	90
14	1c	2h: (E)-PhCH CH	2	syn-5n	79	12 : 1	88
15d	1d	2h: (E)-PhCH CH	4	syn-5o	72	13 : 1	93
16	1e	2h: (E)-PhCH CH	8	syn-5p	69	14 : 1	95
17e	1c	2m: CF3	3	syn-5q	75	3 : 1	90
18e	1d	2m: CF3	2	syn-5r	76	4 : 1	92
19e	1d	2n: CF2H	6	syn-5s	52	2 : 1	87

^aIsolated yield.

^bDetermined by ¹H NMR analysis of the crude reaction mixture.

^cDetermined by HPLC analysis.

^d−20 °C.

^e5 Å MS was replaced by 20 mol% K₂HPO₄·3H₂O.