Transition-metal catalyzed synthesis of delta-hydroxy-gamma-lactones from bis(trimethylsilyl) ketene acetals and allylic acetates via gamma-unsaturated carboxylic acids. Comments on the formation of alpha-cyclopropyl carboxylic acids
H. Rudler et al., Transition-metal catalyzed synthesis of delta-hydroxy-gamma-lactones from bis(trimethylsilyl) ketene acetals and allylic acetates via gamma-unsaturated carboxylic acids. Comments on the formation of alpha-cyclopropyl carboxylic acids, J ORGMET CH, 624(1-2), 2001, pp. 186-202
Bis(trimethylsilyl)ketene acetals react with allylic acetates in the presen
ce of Pd(0) complexes to give gamma -unsaturated carboxylic acids together
with alpha -cyclopropyl carboxylic acids. The unsaturated acids can be conv
erted catalytically to delta -hydroxy-gamma -lactones by the: H2O2/MTO syst
em (methyltrioxorhenium) and to butenolides by Pd(II) catalyzed intramolecu
lar cyclization reactions. The structure of two of these lactones has been
established by X-ray analysis. The mechanism of the formation of the cyclop
ropanic acids will be discussed. (C) 2001 Elsevier Science B.V. All rights
reserved.