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Radical Addition of N ‐Bromophthalimide to Linear and Cyclic Alkynes
Author(s) -
Wille Uta,
Krüger Oliver,
Kirsch André,
Lüning Ulrich
Publication year - 1999
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/(sici)1099-0690(199911)1999:11<3185::aid-ejoc3185>3.0.co;2-m
Subject(s) - chemistry , regioselectivity , radical , steric effects , moiety , free radical addition , yield (engineering) , bromine , vicinal , double bond , addition reaction , medicinal chemistry , stereochemistry , photochemistry , organic chemistry , catalysis , materials science , metallurgy
Addition of N ‐bromophthalimide ( 1 ) to alkynes 3 via phthalimidyl radicals 2 introduces a bromine atom and an imidyl moiety to vicinal C atoms, and highly functionalized alkenes 5 are generated. The regioselectivity of the radical attack is controlled by steric and electronic effects, whereas the stereochemistry at the newly formed CC double bond can be explained by the Curtin–Hammett principle. When this free‐radical addition is applied to the medium‐sized cycloalkyne 8 , the regular addition product 9 is obtained in addition to products resulting from a transannular cyclization. Furthermore, a parallel bromine radical chain is initiated to yield the highly brominated products 11 and 12 .