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A Computational Study of Anionic Alkoxide–Allene and Amide–Allene Cyclizations
Author(s) -
Cumine Florimond,
Young Allan,
Reissig HansUlrich,
Tuttle Tell,
Murphy John A.
Publication year - 2017
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/ejoc.201701381
Subject(s) - chemistry , allene , alkoxide , deprotonation , amide , lithium amide , solvent , lithium (medication) , computational chemistry , photochemistry , organic chemistry , catalysis , ion , enantioselective synthesis , medicine , endocrinology
Computational studies have been performed on potassium alkoxide‐allenes, as well as potassium and lithium amido‐allenes to probe the mechanism of their cyclizations to dihydrofurans and to 2,5‐dihydropyrroles. A long‐standing proposal envisaged electron transfer from dimsyl anions (formed by deprotonation of the solvent DMSO) but this pathway shows an exceptionally high kinetic barrier, while direct 5‐ endo‐trig cyclization of the alkoxides and amides is much more easily achievable. The energy profiles for 4‐ exo‐trig cyclizations onto the allenes are also explored, and the preferred formation of the observed five‐membered products is rationalized.