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Base‐Catalyzed Reactivity of Sulfur‐ and Selenium‐Bridged Cyclic Alkynes: Tandem Isomerization and Cycloaromatization versus Isomerization and Nucleophilic Addition
Author(s) -
Braverman Samuel,
Cherkinsky Marina,
Birsa Mihail L.,
Zafrani Yossi
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200209)2002:18<3198::aid-ejoc3198>3.0.co;2-c
Subject(s) - chemistry , diradical , isomerization , reactivity (psychology) , nucleophilic addition , nucleophile , sulfur , medicinal chemistry , catalysis , stereochemistry , organic chemistry , singlet state , medicine , physics , alternative medicine , pathology , nuclear physics , excited state
The synthesis and base‐catalyzed reactivity of some novel sulfur‐ and selenium‐bridged cyclic di‐ and tetralkynes, derived from 1,2‐ and 1,4‐dihydroxybenzene and 1,2‐bis(bromomethyl)benzene, are described. The cyclic propargylic sulfides and selenides undergo base‐induced isomerization to the corresponding allenes, followed by cycloaromatization of the latter by diradical or anionic mechanisms, depending on the nature of the base. Because of the lack of stability of the expected diradical intermediate, the corresponding allenic sulfones undergo nucleophilic addition, which is responsible for their DNA‐cleaving properties. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)