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Photochemical [2+2] cycloaddition of cyclicenones to(5R)-5-menthyloxy-2[5H]-furanone

✍ Scribed by Samuel Bertrand; Norbert Hoffmann; Jean-Pierre Pete

Publisher
Elsevier Science
Year
1998
Tongue
French
Weight
872 KB
Volume
54
Category
Article
ISSN
0040-4020

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✦ Synopsis

The [2+2] Photocycloaddition of different cyclic enones to (5R)-5-menthyloxy-2[5H]furanone is investigated. The diastereoselectivity relative to the chiral acetal centre and the regio and the exo/endo ratios of the products have been determined. By variation of the structure of cyclic enones, the diastercoselectivity could be optimised to 9/1. The results lead to the conclusion that the photochemically excited cyclopentenone transfer its energy to the (5R)-5-menthyloxy-2[5H]-fumnone. The subsequent reaction of the excited furanone with cyclopentenone in its ground state is less stereoselective, as already observed. However, cyclic enones which furnish mixed adducts with (5R)-5menthyloxy-2[5Hl-furanone with high facial diastercoselectivity, react in their T~ state.

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