Facile Construction of Vicinal Quaternary and Tertiary Stereocenters via Regio- and Stereoselective Organocatalytic Michael Addition to Nitrodienes
作者:Pankaj Chauhan、Swapandeep Singh Chimni
DOI:10.1002/adsc.201100618
日期:2011.11
protocol for the synthesis of vicinal quaternary and tertiary stereocenters has been developed. The 6′-OH Cinchona alkaloids (BnCPN or BnCPD) at low catalyst loading (0.5–5 mol%) catalyze the Michaeladdition of trisubstituted carbon nucleophiles to nitrodienes in good to excellent yield (up to >99), high enantioselectivity (up to 99% ee) and high diastereoselectivity (up to >99:1 dr) under mild reaction
Bifunctional Guanidine via an Amino Amide Skeleton for Asymmetric Michael Reactions of β-Ketoesters with Nitroolefins: A Concise Synthesis of Bicyclic β-Amino Acids
Two activations are better than one: The chiralbifunctional guanidine 1, which features an amino amide backbone, catalyzes the asymmetric Michael addition of a range of substrates and gives products with excellent stereoselectivities. The method also allows the efficient synthesis of optically pure β‐amino acidesters. Both the guanidine group and the NH proton of the amide were important for the