... Heterocyclic Chem., 31, 305 (1994). ... was based on the alkylation of silylated heterocycles following Vor- briiggen and Niedballa's procedure [1]. We have first synthesised the heterocycles VIIb-g ... 2,4- diones VIIa-g. но- HO OH Xa-b, eg XIa-g XIIa,d D BzO-, ОАО \ J ; SnCI4 BzO ...