1.3- Dibromo-2,2-dimethyl propane

The conversion of active-methylene compounds into 2-alkylidene derivatives of 1,3-dithiolans by base-catalysed condensation with carbon disulphide followed by treatment with 1,2-dihalogenoalkanes has been further exemplified, and extended to the synthesis of substituted alkyl-idene derivatives of 1,3-diselenolans and 1,3-diselenans. With dimethyl malonate, carbon diselenide, and either 1,2-dibromoethane or 1,3-dibromo-propane, for example, the compounds (142) and (143), respectively, were formed. Analogously, the dithiolate anion obtained from deoxybenzoin... 

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