Asymmetric formal carbonyl-ene reactions of formaldehyde tert -butyl hydrazone with α-keto esters: Dual activation by bis-urea catalysts

Abstract

The dual activation of α-keto esters and formaldehyde tert-butyl hydrazone by BINAM-derived bis-ureas is the key to achieve high reactivity and excellent enantioselectivities in nucleophilic addition (formal carbonyl-ene reaction) to functionalized tertiary carbinols. Ensuing high-yielding diazene-to-aldehyde tranformations and subsequent derivatizations provides a direct entry to a variety of densely functionalized products. © 2012 American Chemical Society.