Novel Asymmetric Approach to Proline-Derived Spiro-β-lactams
作者:Alisher B. Khasanov、Michele M. Ramirez-Weinhouse、Thomas R. Webb、Mohan Thiruvazhi
DOI:10.1021/jo049430o
日期:2004.8.1
We describe a novel asymmetric approach using Staudinger chemistry to proline-derived spiro-β-lactams. A chiral group at C-4 of the acid chloride of proline directs the stereoselectivity of Staudinger chemistry and later is sacrificed to obtain optically active 5.4-spiro-β-lactams. The scope, limitations, and mechanistic rationale for the observed results of Staudinger Chemistry of the acid chloride
The Nitro-Mannich Reaction and Its Application to the Stereoselective Synthesis of 1,2-Diamines
作者:Harry Adams、James C. Anderson、Simon Peace、Andrew M. K. Pennell
DOI:10.1021/jo981700d
日期:1998.12.1
The addition of alkyl nitronate anions to PMB imines, derived from benzaldehyde or straight-chain carbaldehydes, in the presence of a Bronsted acid, proceeds in greater than 90% yield with up to 10:1 diastereoselection favoring the anti isomer. The mechanism of this addition reaction is intriguing and is under investigation. The moderately unstable p-nitro amines can be reduced with samarium diiodide and the PMB group removed with CAN, in good overall yields, to give sensitive 1,2-diamines without erosion of diastereoselectivity. This protocol represents a new, stereoselective synthesis of certain 1,2-diamines.