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Synthesis of 2-Aryl-3-sulfonylchromans via Knoevenagel Condensation and Reduction Protocol
Meng-Yang Chang1, Han-Yu Chen1, Yu-Hsin Chen1
1Department of Medicinal and Applied Chemistry, Kaohsiung Medical University Hospital, Kaohsiung Medical University , Kaohsiung 807, Taiwan.
Abstract:
In this article, a concise, easy-operational, and high-yield method for the synthesis of 2-aryl-3-sulfonylchromans is described by two-step routes: (i) NH4OAc mediated Knoevenagel condensation of β-ketosulfones and o-hydroxybenzaldehydes in a cosolvent of toluene and THF at reflux for 10 h, and (ii) NaBH4 promoted regio- and stereocontrolled reduction of the resulting 2-arylchromen-2-ols in a cosolvent of MeOH and THF at rt for 1 h. This protocol provides a highly effective (4+2) annulation via one carbon-oxygen and one carbon-carbon bond formations.
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