Synthetic Applications of Aromatic Desilylation and Destannylation

摘要

Two novel electrophilic displacement reactions have been discovered and their scope as synthetic methods examined. The first provides a useful route to aryl nitroso compounds and involves reaction of aryltrimethyl-silanes or -stannanes with nitrosyl chloride (no catalyst being necessary with the stannanes): NOCl + XC6H4MMe3 yields XC6H4NO. The second provides a useful route to aryl cyanides, and involves reaction of the aryltrimethyl -silanes or -stannanes with cyanogen chloride in the presence of aluminium chloride: ClCN + XC6H4MMe3 yields (over AlCl3) XC6H4CN. In both cases the best yields are obtained from the organotin compounds, with methylene chloride as solvent. Reactions with cyanogen bromide take a different course: BrCN + PhSnMe3 yields PhBr + Me3SnCN. Arenesulphonyl chlorides have been found to react with bistrimethylsilylacetylene under Friedel Crafts conditions, and this provides a novel synthesis of ethynyl sulphones: XC6H4SO2Cl + Me3SiCCSiMe3 yields (over AlCl3) Me3SiCCSO2C6H4X. (Author)