Catalytic Nitrene Transfer To Alkynes: A Novel and Versatile Route for the Synthesis of Sulfinamides and Isothiazoles

Abstract

A novel transformation is reported for the reaction of terminal or internal alkynes with the nitrene precursor PhI=NTs (Ts=p-toluenesulfonyl) in the presence of catalytic amounts of Tp(Br3)Cu(NCMe) (Tp(Br3)=hydrotris(3,4,5-tribromo-pyrazolylborate). Two products containing an imine functionality have been isolated from the reaction mixtures, identified as sulfinamides and isothiazoles. The former correspond to the formal reduction of the sulfone group into sulfoxide, whereas the latter involves the insertion of an alkyne carbon atom into the aromatic ring of the N-tosyl moiety.Support for this work was provided by the MINECO (CTQ2014-52769-C3-R-1, CTQ2014-57761-R, Severo Ochoa Excellence Accreditation 2014-2018 SEV-2013-0319, Red Intecat CTQ2014-52974-REDC) and by a FPU fellowship (M.R.R.). We thank Prof. Antonio Echavarren for helpful comments and discussions