Nucleophic addition

Similar nucleophic addition is observed with the analogous osmium complex 147 (Scheme 21). X-Ray structural analysis of 247 (R = n-C4H9) shows that the n-butyl group occupies the exo position (152). Complexes of type 247 react smoothly with trityl cation in acetone to give the arene... 

APPLICATIONS OF ORGANOMETALLIC COMPOUNDS Enhanced acidity and nucleophic addition... 

The following molecular model represents a tetrahedral intermediate resulting from addition of a nucleoph ile to an aldehyde or ketone. Identify the reactants, and write the structure of the final product when the nucleophilic addition reaction is complete. 

A second route involves preforming first the allylic halide addition to form the iminium salt arising from the alkylation on the highly nucleophic sulfur atom. Subsequent treatment with triethylamine provided the S-allyl thioimidoester which was usually not observed but underwent a deprotonation and a fast [3,3] sigmatropic transposition to give the a-allyl thioamide. With pyroglutamate derivatives no diastereoselectivity was found. An analogous sequence [197] was used with a thioacyl proline derivative, with some stereoselectivity. 

The work of Steven Davies23 at Oxford has made conjugate addition of nitrogen nucleoph 0 a reliable and useful reaction. The essential reagent is the amine 121, prepared on a large resolution (chapter 22). This amine does not react with unsaturated esters like 123 but the derivative 122 adds in a conjugate fashion to give the ester 125 via the enolate 124. 

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