STEREOCHEMISTRY OF ELECTROPHILIC SUBSTITUTION-REACTIONS OF INDENYL-ORGANOTIN COMPOUNDS

The stereochemistry of the reactions of S-(+)-(3-methylindenyl)trimethylstannane (I) with C6H5COOH, BrCN and HgCl2 in dimethoxyethane (DME), and of S-(+)-(1-methyl-3-phenylindenyl)trimethylstannane (II) with C6H5COOH and BrCN in C6H6 has been investigated. The reaction products were identified by GLC and 1H NMR spectroscopy. It was found that the interaction of S-(+)-I with C6H5COOH yielded a mixture of 2% R-(-)-1-methylindene and 98% 3-methylindene. With C6H5COOD S-(+)-3-methylindene-1-d1 was formed. The reaction of S-(+)-I with BrCN gave R-(-)-1-bromo-3-methylindene and S-(+)-1-bromo-1-methylindene, the reaction of S-(+)-I with HgCl2 yielded R-(-)-(3-methylindenyl)mercury chloride. In the reaction of S-(+)-II with BrCN R-(-)-1-bromo-1-methyl-3-phenylindene was formed, and the reaction with C6H5COOH gave an optically inactive mixture of 1-methyl-3-phenyl- and 1-phenyl-3-methylindenes ( 1 2). The observed stereochemical result is explained by anti-attack of the electrophilic agent with reaction centre transfer (SE2′ mechanism). © 1979.