Table 3. Lactonization Reaction Using cis- or trans-Stilbene^a,b.

				diastereomer
entry	conditions	1s	3 (%)	A	B	C	D
1	cis-selective conditions	Z	49	52	9	22	17
2		E	70	43	24	21	12
3	trans-selective conditions	Z	41	52	31	0	17
4		E	73	53	35	0	18

^aReaction conditions: cis-selective conditions: 1 (2 equiv), 2a (0.3 mmol), I₂ (0.3 mmol), and Ca(OH)₂ (0.3 mmol) in ^tBuOH (3 mL) were stirred at ambient temperature and irradiated with a compact fluorescent lamp (CFL) for 20 h. trans-Selective conditions: 1 (2 equiv), 2a (0.3 mmol), I₂ (0.3 mmol), and Na₂CO₃ (0.3 mmol) in ^tBuOH (2 mL) and H₂O (1 mL) were stirred at ambient temperature and irradiated with compact fluorescent lamps (CFLs) for 20 h.

^bDiasteromeric ratios (dr) were determined by ¹H NMR analysis of the crude reaction mixture.