Reduction of Sulfonylimines with Raney Nickel

Abstract

Raney-Ni/EtOH reduction of different N-sulfonylimines provides a new entry for synthesizing sulfonamides in good yields under mild conditions. This protocol, which does not require additional hydrogen, constitutes a cheap, safe, and easy-to-handle alternative procedure to prepare α-branched sulfonamides.

GRAPHICAL ABSTRACT

Keywords:

• α-Branched amines
• α-branched sulfonamides
• C=N reductions
• Raney Ni
• N-sulfonylimines

ACKNOWLEDGMENTS

We thank the DGYCT (CTQ2009-12168-BQU) and Comunidad Autónoma de Madrid (S2009/PPQ-1634) for financial support. J. A. F.-S. thanks Comunidad Autónoma de Madrid for a predoctoral contract.

Notes

^a Measured by ¹H NMR. ^b Only decomposition was observed.

^a 1.5 g of Raney Ni were used.

^b Reflux was necessary.

^c Complex mixture (see text).

^d Na₂SO₄ was used as water scavenger.

^a A 50% conversion was obtained after 10 h at rt.

^b Na₂SO₄ was used as water scavenger.