α-Pyridylation of Chiral Amines via Urea Coupling, Lithiation and Rearrangement
作者:Jonathan Clayden、Ulrich Hennecke
DOI:10.1021/ol801332n
日期:2008.8.21
2-, 3- and 4-Bromopyridine, along with other brominated electron-deficient arenes, undergo palladium-catalyzed coupling with ureas of structure RNMeCONHMe. Where R is a chiral, alpha-substituted benzyl group, treatment with LDA leads to a benzylic organolithium which undergoes rearrangement with stereospecific and regiospecific transfer of the pyridyl group, generating a quaternary stereogenic center
Substituted Diarylmethylamines by Stereospecific Intramolecular Electrophilic Arylation of Lithiated Ureas
作者:Jonathan Clayden、Jérémy Dufour、Damian M. Grainger、Madeleine Helliwell
DOI:10.1021/ja071523a
日期:2007.6.1
On lithiation, N-benzyl ureas varying N‘-aryl substituents undergo a migration of the aryl ring to the α carbon of the N-benzylgroup. With chiral, enantiomerically pure N-α-methylbenzyl ureas, the rearrangement is stereospecific and creates a new, fully substituted stereogenic center α to N. Removal of the urea function by N-nitrosation and hydrolysis allows the synthesis of chiral tertiary carbinamines