Hydrazones, 0-stannyl

Entry 21 involves addition to a glyoxylic hydrazone and the cis ring junction is dictated by strain effects. The primary phenylselenyl group is reductively removed under the reaction conditions. Entry 22 involves generation of a stannyloxy radical by addition of the stannyl radical at the carbonyl oxygen. Cyclization then ensues, with the cis-trans ratio being determined by the conformation of the cyclization TS. 

The hydrazone 308 underwent carbozincation and stannylation providing the intermediate 309, which was subsequently annulated to the 1-aminopyrrole derivative 310 (Scheme 36) <1999OL1505>. 

J2J2j6 -Stannyl Hydrazones, Oximes and Carboxylic Acids... 

Michael addition of trialkylstannyllithium to cyclohexenone SAMP- or RAMP-hydrazone gives 3-stannyl derivatives with de values of 42-44%, while subsequent alkylation of the enolate formed affords trans-products with de values >96%. The hydrazones obtained are subjected to ozonolysis to give 3-stannylcyclohexanones trans-1 with ee values up to 96%17. 

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