The decomposition of cyclohexyl diazo(triethylsilyl)acetate 2a and the t-butyl derivatives 3a,b with [Rh-2(S)-ntt}(4)] and similar chiral Rh(II)-catalysts proceeds in toluene at room temperature to produce silylated lactones in up to 90% yield. The reaction is highly stereoselective. Enantioselectivities of up to 79% have been observed. (C) 2003 Elsevier Science Ltd. All rights reserved.