Table 1. Optimization of Reaction Conditions in the Formation of 3a^a.

entry	catalyst	base (aq.)	solvent T (°C)	time (days)	yield (%)b	dr (3a:3aa)c	ee (%)c	entry	catalyst	base (aq.)	solvent	T (°C)	time (days)	yield (%)b	dr (3a:3aa)c	ee (%)d,e
a	4a	Na2CO3	toluene 25	3	45	92:8	10	l	4e	NaOH	toluene	25	1	20	90:10	5
b	4b	Na2CO3	toluene 25	2	60	93:7	5	m	4e	CsOH	toluene	25	1	25	95:5	10
c	4c	Na2CO3	toluene 25	4	80	93:7	55	n	4e	Na2CO3	xylene	0	3	98	99:1	99
d	4d	Na2CO3	toluene 25	3	85	98:2	60	o	4e	Na2CO3	toluene	0	3	60	99:1	65
e	4e	Na2CO3	toluene 25	2	90	99:1	85	p	4e	Na2CO3	MTBE	0	3	50	99:1	30
f	4f	Na2CO3	toluene 25	4	40	95:5	50	q	4e	Na2CO3	benzene	0	3	55	99:1	40
g	4g	Na2CO3	toluene 25	5	45	89:11	30	r	4e	Na2CO3	DCE	0	3	35	99:1	20
h	4h	Na2CO3	toluene 25	4	50	88:22	25	s	4e	Na2CO3	xylene	–20	4	35	99:1	40
i	4i	Na2CO3	toluene 25	5	40	90:10	30	t	4e	Na2CO3	toluene	–40	5	30	99:1	30
j	4e	K2CO3	toluene 25	2	80	99:1	70	u	4e	Na2CO3	toluene	–78	2
k	4e	Cs2CO3	toluene 25	2	65	95:5	20

^aAll reactions were performed at 0.21 mmol of 1, 0.25 mmol of 2, 5 mol % 4e and 0.2 mL of aqueous base in 5 mL of solvent.

^bIsolated yields after column chromatography.

^cDiastereomeric ratio was determined by ¹H NMR.

^dEnantiomeric excess was determined by chiral high-performance liquid chromatography (HPLC).

^eEnantiomeric ratio of the major diastereomer.