TABLE 5.

Discovery and Optimization of the Cui-Mediated Photochemical Cascade Cyclization of 29a into 42b

entry	irrada(nm)	heatb(°C)	conditions	yieldc(%)	42b/43b ratiod
a		110	no additives	80	1:1.6
b	254		no additives	67	1:1
b	254		excess CuI, LiBr, Mg powder	33	>10:1
d	254		LiBr (1 equiv)	68	1:1.1
e	254		Mg powder	(33)e	1:1.2
f	254		LiBr (1 equiv), CuI (0.05 equiv)	f	1:1.4
g	254		LiBr (1 equiv), CuI (1 equiv)	21	5.4:1
h	254		CuBr·SMe2 (1 equiv)	f	2.8:1
i	254		CuBr·SMe2 (0.25 equiv)	(17)e	1.6:1
j	254		Cu(OAc)2 (1 equiv)	f	5:1
k	254		CuI (0.5 equiv)	67	4:1
l	254		CuI (0.8 equiv)	72	6: 1
m	254		CuI (1.2 equiv)	67	9:1
n	254		CuI (1.5 equiv)	70	10:1
o		110	CuI (1.5 equiv), 5 mM	75	1:1.6
p		110	CuI (1.5 equiv), 35 mM	66	3.5:1
q		110	CuI (1.5 equiv), 51 mM	65	5:1
r	254		[Rh(OAc)2]2 (1 equiv)	(48)e	1:1

^aIrradiated through a quartz vessel as a 5 mM CH₃CN solution of 28a.

^b100 mM solution in toluene, unless otherwise noted.

^cIsolated, chromatographically purified material. The N-cyclized material had undergone elimination to furnish the diene 44b (see Table 6).

^dRatio by integration of the ¹H NMR spectrum of the crude reaction mixture prior to chromatography.

^eOnly the N-cyclized material was isolated; 42b decomposed upon attempted chromatography.

^fProducts were not isolated.