Inverted regioselectivity of C–H amination: Unexpected oxidation at β- rather than γ-C–H

Abstract

A rare example of β- over γ-C–H selectivity during Rh-catalysed sulfamate ester cyclisation is presented; from derivatives of 1,6-anhydro-β-D-mannopyranose, five-membered sulfamidates were formed in preference to the typical six-membered oxathiazinane intramolecular insertion products. A 3D structure of sulfamate 1 helps to rationalise this unusual selectivity and analyses suggest that n→σ*(CH) interactions may be a key controlling factor.