Chirality multiplication and efficient chirality transfer in exo- and endo-radical cyclization reactions of 4-(4'-iodobutyl)quinolones.
[reaction: see text] Enantioselective radical cyclization reactions were performed in the presence of chiral complexing agent 1. The title compounds 3 yielded, depending on the 3'-substitution (R = H, Me), the corresponding endo- (4) or exo-product (5). The highest enantioselectivities (99% and 94% ee) were achieved with 2.5 equiv of complexing agent. The cyclization product trans-4 was obtained in 55% ee in the presence of only 0.1 equiv of complexing agent.
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