Azirine/oxindole ring enlargement via amidinium intermediates

…, S Bienz, A Linden, H Heimgartner

Index: Mekhael, Maged K. G.; Bienz, Stefan; Linden, Anthony; Heimgartner, Heinz Helvetica Chimica Acta, 2004 , vol. 87, # 9 p. 2385 - 2404

Full Text: HTML

Citation Number: 9

Abstract

Abstract A novel general method for the synthesis of oxindoles, namely the 'azirine/oxindole ring enlargement via amidinium-intermediates' has been established: the reaction of 2H- azirin-3-amines 1 with BF 3⋅ OEt 2 in THF solution at− 78 leads to 1, 3, 3-trialkyl-2-amino- 3H-indolium tetrafluoroborates 14 in good yields (Scheme 5). Treatment of aqueous solutions of 14 at 0 with aqueous NaOH (30%) and extraction with CH 2 Cl 2 gives oily ...