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Diels‐Alder Reactions of 5,8‐Ethano‐5,8‐dihydro‐1,4‐naphthoquinone with Cyclic Dienes
Author(s) -
Chou TehChang,
Liou JingAnn,
Lin ChengTung
Publication year - 1994
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199400075
Subject(s) - chemistry , cyclopentadiene , bicyclic molecule , diels–alder reaction , naphthoquinone , double bond , stereoselectivity , enone , acetone , medicinal chemistry , stereochemistry , organic chemistry , catalysis
Diels‐Alder cycloadditions of 1,3‐cyclohexadiene and cyclopentadiene to π ‐facially dissymmetric 5,8‐ethano‐5,8‐dihydro‐1,4‐naphtboquinone (1) were examined. The stereochemical outcome of the reactions, determined by a combination of chemical and spectral methods, indicates that addition of cyclic dienes to 1 occurs preferentially at the face syn to the etheno‐bridge of 1. Cycloadducts 7a/7b and 8a/8b obtained from Diels‐Alder reactions of 1 with cyclopentadiene and 1,3‐cyclohexadiene undergo [2+2]‐photocyclization to give caged compounds 9a/9b and 10a/10b , respectively. Stereoselective reduction of the enedione double bond in 7a/7b and 8a/8b with aqueous TiCl 3 in acetone affords cis‐bis‐bicyclic ring‐fused 1,4‐cyclo‐hexadiones 11a/11b , and 12a/12b , respectively.