Generation of (α‐aminoalkyl)samarium(III) by a new method of metalation and its carbon–carbon bond‐forming reactions

Abstract

Abstract(α‐Aminoalkyl)samarium(III) is generated on treatment of a tertiary amine having a pendant o‐iodobenzyl group on the nitrogen atom with samarium(II) iodide (SmI2) in tetrahydropyran containing hexamethylphosphoramide. Deuterium incorporation experiments demonstrate that the reaction proceeds via a delivery of a radical center from the pendant benzyl group to the α‐position of nitrogen and the following one‐electron transfer from SmI2 to the delivered radical. Subsequent nucleophilic addition of (α‐aminoalkyl)samarium (III) to various electrophiles, such as enolizable ketones, isocyanate and isocyanide, furnishes the C‐C bond formation products in good yields. The pendant benzyl group of the product can be readily removed by hydrogenolysis to give the corresponding secondary amine. Therefore, the present reaction provides a useful synthetic process for a variety of nitrogen‐containing compounds including β‐amino alcohols and α‐amino acid derivatives, disclosing a new method for metalation and C‐C bond formation.