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Paper | Special issue | Vol 64, No. 1, 2004, pp.101-120
Published online, 30th March, 2004
DOI: 10.3987/COM-04-S(P)3
Asymmetric Synthesis of Heterocyclic β-Aminosulfones via Nucleophilic 1,2-Addition of 2-Lithiobenzo[b]thiophene to Aldehyde-SAMP-hydrazones

Dieter Enders* and Giuseppe Del Signore

*Institut für Organische Chemie, Rheinisch-Westfälische, Technische Hochsch, Aachen University, Professor-Pirlet-Straße 1, D-52074 Aachen, Germany

Abstract

An efficient asymmetric synthesis of α-(1,1-dioxo-2,3-dihydro-1H-1λ6-benzo[b]thiophen-2-yl)-substituted amines is described. Key steps of the synthesis are the nucleophilic 1,2-addition of 2-lithio-benzo[b]thiophene to aldehyde-SAMP-hydrazones, a benzo[b]thiophene oxidation using dimethyldioxirane and a highly diastereoselective conjugate reduction with L-Selectride.® The heterocyclic β-aminosulfones are obtained in five steps and good overall yields (23-49%) and very high diastereo-and enantiomeric excesses (de > 96%, ee = 88-99%).