Inverted regioselectivity of C-H amination: Unexpected oxidation at beta- rather than gamma-C-H.
A rare example of beta- over gamma-C-H selectivity during Rh-catalysed sulfamate ester cyclisation is presented; from derivatives of 1,6-anhydro-beta-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-->sigma*(CH) interactions may be a key controlling factor.
Wyszynski
Filip J
FJ
Department of Chemistry, University of Oxford, Chemistry Research Laboratory, 12 Mansfield Road, Oxford, UKOX1 3TA.
Thompson
Amber L
AL
Davis
Benjamin G
BG