ABSTRACT
We report the synthesis of α-trifluoromethyl benzylic amines through the vicinal fluoroarylation of gem-difluoro-2-azadienes. Our studies indicate that XPhos plays an important role as a phase transfer catalyst that promotes the addition of AgF to the difluoroazadiene, generating an α-trifluoromethyl azaallyl-silver intermediate that we have characterized by NMR spectroscopy. This intermediate likely transmetallates to Pd, coupling several aryl iodides to deliver products in up to 90% yield. Modification of the azadiene's activating group facilitates challenging cross-couplings.
ABSTRACT
We report the direct preparation of 1,3-amino alcohols that contain up to three contiguous stereogenic centers by the umpolung coupling of imines and epoxides. Nucleophilic 2-azaallyl anions, generated from imines, are stereoselectively added to epoxides to furnish 1,3-amino alcohols after hydrolysis of the product imine. Transformations afford amino alcohols with >98% site selectivity with respect to both reaction partners and in up to >98% yield and >20:1 dr.
ABSTRACT
Dienoic acids and pentadienyl alcohols are coupled in a decarboxylative and dehydrative manner at ambient temperature using Pd(0) catalysis to generate 1,3,6,8-tetraenes. Contrary to related decarboxylative coupling reactions, an anion-stabilizing group is not required adjacent to the carboxyl group. Of mechanistic importance, it appears that both the diene of the acid and the diene of the alcohol are required for this reaction. To further understand this reaction, substitutions at every unique position of both coupling partners was examined and two potential mechanisms are presented.
