Table 3.

Regiochemistry in Iodolactonization of 5-Substituted-4(E)-pentenoic Acids^a

entry	R	product	yieldb (%)	erc,d
a	i-Pr	10a	78	67:33
b	Ph	10b+11b	89e	52:48(95:5)f
c	p-MeO-C6H4	11c	89	86.5:13.5
dg	p-NC-C6H4	10d	94	58:42

^aReactions run on 0.1 mmol scale.

^bIsolated yield after column chromatography.

^cer determined by chiral HPLC.

^dAbsolute stereochemistry of iodolactones was assigned based on analogy with corresponding bromolactone analogs.³ⁱ

^eCombined yield; ratio of 1.3:1.0 based upon NMR analysis.

^fer shown in parentheses is for 11b,

^gReaction performed for 14 h at −20 °C and 48 h at −10 °C in CH₂Cl₂/tol (1:1).