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The preparation of 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides from the condensation‐cyclization of dilithiated β‐ketoesters with methyl 2‐(aminosulfonyl)benzoate or 1,2‐benzisothiazol‐3(2 H )‐one‐1,1‐dioxide
Author(s) -
Meierhoefer Michelle A.,
Walters Matthew J.,
Patrick Dunn S.,
Vella Jarrett H.,
Grant Bonnie J.,
Sober Carolyn L.,
Patel Nidhi S.,
Hajiaghamohseni Laela M.,
Lioi Sara B.,
Metz Clyde R.,
Beam Charles F.,
Pennington William T.,
Vanderveer Donald G.,
Dwight Camper N.
Publication year - 2006
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570430209
Subject(s) - chemistry , sulfonamide , lithium diisopropylamide , tautomer , organic chemistry , saccharin , medicinal chemistry , recrystallization (geology) , ethanol , deprotonation , ion , medicine , paleontology , biology , endocrinology
everal β‐ketoesters were dilithiated with an excess of lithium diisopropylamide, followed by condensation with methyl 2‐(aminosulfonyl)benzoate to give intermediates that were not isolated but cyclized to 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides. In most instances involving the ester‐sulfonamide, a single β‐ketoester tautomer is usually formed after recrystallization from ethanol. The same dilithiated β‐ketoesters generally condense less well with 1,2‐benzisothiazol‐3(2 H )‐one‐1,1‐dioxide (saccharin) under the same conditions to afford the same products usually in the same or lower yields. The use of N,N,N',N' ‐tetramethylethylenediamine during these syntheses has sometimes resulted in improved yields of products.