Table 1. Optimization of Ene Reactions^a.

entry	substrate	conditions	time (h)	2a/4a (equiv)	yield 3a/5a (%)
1	2a	MeCN	4	1	67
2	2a	MeCN	4	2	88
3	2a	MeCNb	8	2	21
4	2a	MeCNc	4	2	n.r.
5	2a	toluene	4	2	20
6	2a	Et2O	4	2	38
7	2a	CH2Cl2	4	2	38
8	2a	THF	3	2	31
9	2a	MeOH	3	2	44
10	4a	KF, THFd	12	1.2	85
11	4a	CsF, MeCN	12	1.2	82
12	4a	KF, THFd	12	1.5	96
13	4a	KF, THFd	4	1.5	98
14e	4a	KF, THFd	4	1.5	98

^aReactions were carried out using 0.1 mmol of 1a (for reaction with 2a) or 0.2 mmol scale of 1a (for reaction with 4a). Isolated yields are reported.

^bReaction conducted at 0 °C.

^cReaction carried out in the dark.

^dReaction conducted with 1 equiv 18-C-6 per equiv. KF.

^ePerformed on 1.0 mmol scale. n.r. = no reaction.