Organic Letters 2011-05-06

Multicomponent Mannich reactions with boron enolates derived from diazo esters and 9-BBN.

Yi Luan, Scott E Schaus

Index: Org. Lett. 13 , 2510, (2011)

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Abstract

Diazo esters, arylboranes, and carbamoyl imines undergo a 3-component Mannich condensation reaction. Catalyzed by Cu(II) salts, the reaction affords the corresponding isocyanate Mannich product: one that can be easily trapped in situ by other nucleophiles. The Mannich condensation corresponds to an α,α-disubstituted enolate addition to imines. The reaction was rendered asymmetric by using the (-)-phenylmenthol ester in good yield and selectivities.