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Polarity Matching of Radical Trapping: High Yielding 3‐ exo and 4‐ exo Cyclizations
Author(s) -
Gansäuer Andreas,
Lauterbach Thorsten,
GeichGimbel Daniel
Publication year - 2004
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.200400685
Subject(s) - chemistry , chemoselectivity , radical , electrophile , cyclobutanes , nucleophile , enol , photoredox catalysis , catalysis , photochemistry , medicinal chemistry , umpolung , combinatorial chemistry , organic chemistry , cycloaddition , photocatalysis
A catalyzed synthesis of cyclopropanes and cyclobutanes via radical chemistry is described. The method that generally proceeds in high yields uses epoxides as radical precursors and titanocene( III ) complexes as the electron transfer catalysts (see scheme). The key to the success of the transformation is constituted by the chemoselectivity of radical reduction. Electrophilic enol radicals generated through cyclization are reduced rapidly whereas their precursors, nucleophilic alkyl radicals, remain unaffected.