Diastereoselective synthesis of atropisomers containing two non-biaryl stereogenic axes: stereochemical relay through stereogenic centres in dihydrostilbene-2,2′-dicarboxamides
Synthesis of atropisomeric diamides with remotely related stereogenic axes by stereoselective additions to imines
作者:Jonathan Clayden、Neil Westlund、Francis X. Wilson
DOI:10.1016/s0040-4039(99)00520-1
日期:1999.4
Atroposelective addition of axially chiral laterally lithiated 2-alkyl-1-naphthamides to 6-substituted 2-(N-methylformimino)benzamides leads, after equilibration of the new stereogenic axis to its more stable conformation, to single atropisomeric diastereoisomers of diamides bearing remotely related stereogenic axes separated by one or two stereogenic centres. The newly created MeNH-bearing stereogenic centre "relays" stereochemical information from the first axis to the second. (C) 1999 Elsevier Science Ltd. All rights reserved.
Atroposelective attack of nucleophiles on 2-formyl-1-naphthamides and their derivatives: chelation and non-chelation control
作者:Jonathan Clayden、Catherine McCarthy、Neil Westlund、Christopher S. Frampton
DOI:10.1039/b000669f
日期:——
Organometallic nucleophiles attack 2-formyl-1-naphthamides to give secondary alcohols with widely varying atroposelectivity. By careful choice of reagent, selectivities of up to >99∶1 in favour of either the anti or the syn atropisomer can be obtained. Ethers and amines may be synthesised atroposelectively from acetals or imines. The sense of the selectivity is determined by the reactive conformation of the Ar–CHO bond, itself dependent on the coordinating and chelating ability of the nucleophile’s counterion. The roles of conformation, Lewis acids, and chelation/non-chelation control in relation to stereoselectivity are discussed.
Diastereoselective synthesis of atropisomers containing two non-biaryl stereogenic axes: stereochemical relay through stereogenic centres in dihydrostilbene-2,2′-dicarboxamides
作者:Jonathan Clayden、Neil Westlund、Christopher S. Frampton、Madeleine Helliwell
DOI:10.1039/b514561a
日期:——
Addition of laterally lithiated tertiary aromatic amides to benzaldimines controls the formation of a new stereogenic centre adjacent to the benzaldimine aromatic ring. Drawing on the fact that such amino-substituted stereogenic centres may themselves control the conformation of amides, with amido-substituted benzaldimines we found it becomes possible to relay stereochemistry from one amide to another via this intervening stereogenic centre. A group of dihydrostilbene-2,2â²-dicarboxamide derivatives bearing one or two stereogenic axes are made by this method, which demonstrates the use of combined kinetic and thermodynamic control for the relay of stereochemical information.