Mixed Cyano-Gilman Cuprates - Advances in Conjugate Addition to α,β-Unsaturated Pyroglutaminol

Abstract

Conjugate addition of lower order cuprates to protected α,β-unsaturated pyroglutaminol 1 is of limited value, mainly due to the requirement for a large excess of the transferable ligand (10 equiv). Here we report advances using mixed cyano-Gilman cuprates which allow the use of only 1.2 equiv of the transferable ligand, to give the desired product in acceptable to good yield (68-84%). Diethyl ether as the solvent was found advantageous versus THF, since the use of TMSCl could be avoided.

Key words

cuprates - lactams - amino acids - addition reactions - asymmetric synthesis

References

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12

The chemical purity of the commercially available trans-2-trimethylsilylvinylbromide was estimated to be approximately 85%.