Rationally Designed Amide Donors for Organocatalytic Asymmetric Michael Reactions
作者:Bin Tan、Gloria Hernández-Torres、Carlos F. Barbas
DOI:10.1002/anie.201200996
日期:2012.5.29
Amide nucleophiles on demand: Rationallydesigned pyrazoleamides function as Michaeldonors in urea‐catalyzed asymmetricMichaelreactions with excellent chemical and optical yields (see scheme). The pyrazoleamide group performs as an ester equivalent, a directing group, an activating group, and functions as a good leaving group in further transformations of the product.
one-pot two-step protocol for the first direct, base-catalyzed α-trifluoromethylthiolation of carboxylic acid derivatives by using readily available N-acyl pyrazoles, N-(trifluoromethylthio)phthalimide and a nucleophile such as amines, alcohols and water. Straightforward elaboration of the products to alcohols and triflones expands further the synthetic utility of the process.
An efficient asymmetric Mannich/cyclizationcascade strategy was established from 2‐benzothiazolimines with N‐acylpyrazoles to provide optical active benzothiazolopyrimidine derivatives using a copper‐based complex. The mild cascade process constructed various structurally diverse products with broad scope of substrates together with excellent enantioselectivities (up to 99 % ee) and diastereoselectivities
An organocatalytic asymmetric Mannich reaction of pyrazoleamides with cyclic trifluoromethyl ketimines: enantioselective access to dihydroquinazolinone skeletons
An organocatalyzed asymmetricMannichreaction of pyrazoleamides and cyclic trifluoromethyl ketimines with a chiral bifunctional amine-squaramide as the catalyst was developed. A wide range of trifluoromethyl dihydroquinazolinone derivatives bearing adjacent quaternary and tertiary stereogenic centers were readily obtained in good to excellent yields (up to 99%) with high diastereo- and enantioselectivities
A highlyorganocatalyzed asymmetric Michael addition reaction of pyrazoleamides to β-phthalimidonitroethene has been developed with a chiral bifunctional thiourea-tertiary amine as the catalyst. A wide range of γ-nitro β-amino amides were readily obtained in good to excellent yields with high diastereo- and enantioselectivities (up to 99% yield, 99% ee and >20:1 dr). The large scale experiment and