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Diastereodifferentiating the [2+2] Photocycloaddition of Ethylene to Arylmenthyl Cyclohexenonecarboxylates: Stacking‐Driven Enhancement of the Product Diastereoselectivity That Is Correlated with the Reactant Ellipticity
Author(s) -
Tsutsumi Ken,
Yanagisawa Yuuki,
Furutani Akinori,
Morimoto Tsumoru,
Kakiuchi Kiyomi,
Wada Takehiko,
Mori Tadashi,
Inoue Yoshihisa
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000429
Subject(s) - diastereomer , moiety , substrate (aquarium) , substituent , chemistry , cyclohexenone , stacking , ethylene , yield (engineering) , stereochemistry , photochemistry , organic chemistry , materials science , catalysis , oceanography , metallurgy , geology
Abstract Upon diastereodifferentiating the [2+2] photocycloaddition of ethylene to a series of p ‐substituted (−)‐8‐phenylmenthyl cyclohexenonecarboxylates, the diastereoselectivity was critically controlled by the nature of the substituent introduced to the chiral auxiliary, and the p ‐nitro‐substituted substrate afforded the cycloadducts in 90 % diastereomeric excess ( de ) and with 97 % isolated yield. Detailed experimental and theoretical conformation analyses revealed that the stacking interaction of the aromatic auxiliary with the cyclohexenone moiety plays the decisive role in determining the substrate conformation and is, therefore, responsible for the dramatic enhancement of the de . Of particular interest, the product de was directly related to the ellipticity of the substrate, enabling us to “predict” the de prior to photoirradiation.