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<i>H</i>)-one-1,1-dioxide
作者:Michelle A. Meierhoefer、Matthew J. Walters、S. Patrick Dunn、Jarrett H. Vella、Bonnie J. Grant、Carolyn L. Sober、Nidhi S. Patel、Laela M. Hajiaghamohseni、Sara B. Lioi、Clyde R. Metz、Charles F. Beam、William T. Pennington、Donald G. Vanderveer、N. Dwight Camper
DOI:10.1002/jhet.5570430209
日期:2006.3
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(2H)-one-1,1-dioxide (saccharin) under the same conditions to afford
用过量的二异丙基氨基锂将数种β-酮酸酯二甲酸酯化,然后与2-(氨基磺酰基)苯甲酸甲酯缩合,得到未分离但环化为3-取代的1,2-苯并噻唑-1,1-二氧化物的中间体。在大多数涉及酯-磺酰胺的情况下,通常在从乙醇中重结晶后形成单个β-酮酯互变异构体。通常,在相同条件下,相同的二片化β-酮酸酯与1,2-苯并噻唑-3(2 H)-one-1,1-二氧化物(糖精)的缩合不太好,通常以相同或较低的收率得到相同的产物。在这些合成过程中使用N,N,N′,N′-四甲基乙二胺有时可以提高产物的产率。