Synthesis and Synthetic Applications of Samarium Enolates of Unmasked Amides: Efficient Synthesis of 3-Aminoamides and 3-Amino-2-chloroamides

Abstract

Unprotected samarium acetamide and chloroacetamide enolates were prepared by treatment of iodoacetamide and dichloroacetamide with SmI₂. The addition of these samarium-based enolates to aldimines was efficiently performed affording 3-aminoamides and 3-amino-2-chloroamides in high yields. A mechanism is proposed to explain the synthesis and reactivity of samarium enolates of primary amides.

Key words

amides - enolates - samarium

References and Notes

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7

For a recent review on samarium enolates, see ref. 4l.

10

General Procedure for the Synthesis of 3-Aminoamides 1 A solution of iodoacetamide 3 (0.4 mmol) and the corresponding N-tosylaldimine 2 (0.4 mmol) in THF (2 mL) was treated with a 0.1 M solution of SmI₂ in THF (10 mL, 1 mmol). After 3.5 h at r.t. the reaction mixture was quenched with HCl (1.0 M, 20 mL). Usual workup and purification by flash column chromatography (hexane-EtOAc, 3:1) afforded pure compounds 1.