Stereoselective Alkylation of α,β-Unsaturated Imines via C−H Bond Activation
作者:Denise A. Colby、Robert G. Bergman、Jonathan A. Ellman
DOI:10.1021/ja0584931
日期:2006.5.1
alkylation of α,β-unsaturated imines via C−H activation followed by imine hydrolysis produces tri- and tetrasubstitutedα,β-unsaturated aldehydes. In the presence of a rhodium catalyst, α,β-unsaturated N-benzyl imines derived from methacrolein, crotonaldehyde, and tiglic aldehyde undergo directed C−H activation at the β-position and react with terminal alkenes and alkynes to form the tri- and tetrasubstituted
Synthesis of Dihydropyridines and Pyridines from Imines and Alkynes via C−H Activation
作者:Denise A. Colby、Robert G. Bergman、Jonathan A. Ellman
DOI:10.1021/ja7104784
日期:2008.3.1
A convenient one-pot C-H alkenylation/electrocyclization/aromatization sequence has been developed for the synthesis of highly substituted pyridine derivatives from alkynes and alpha,beta-unsaturated N-benzyl aldimines and ketimines that proceeds through dihydropyridine intermediates. A new class of ligands for C-H activation was developed, providing broader scope for the alkenylation step than could be achieved with previously reported ligands. Substantial information was obtained about the mechanism of the reaction. This included the isolation of a C-H activated complex and its structure determination by X-ray analysis; in addition, kinetic simulations using the Copasi software were employed to determine rate constants for this transformation, implicating facile C-H oxidative addition and slow reductive elimination steps.
Reactions of 1-Aza-1,3-butadienes. An Expedient Synthesis of Unsymmetrically Substituted N-Benzyl-1,4-dihydropyridines and N-Benzyl-1,4-dihydronicotinamides.
作者:Jon K. F. Giersson、Jonina F. Johannesdóttir、Johannes Reynisson、Juhani Huuskonen、Kari Rissanen、Wenjun Shi、Stenbjörn Styring、Cecilia Tommos、Kurt Warncke、Bryan R. Wood
DOI:10.3891/acta.chem.scand.51-0348
日期:——
New synthesis of 2,2′-heteroarylpyrroles from heteroarylchlorocarbenes
作者:Yuri N. Romashin、Michael T.H. Liu、Wei Ma、Robert A. Moss
DOI:10.1016/s0040-4039(99)01398-2
日期:1999.10
2,2'-Pyridyl- and 2,2'-thienylpyrroles containing substituents at the 1- and 3-positions of the pyrrole ring have been prepared from the reaction of heteroarylchlorocarbenes with 1-azabuta-1,3-dienes. Laser flash photolysis of heteroarylchlorocarbene in isooctane in the presence of 1-azabuta-1,3-diene yields an azomethine ylide (lambda=550 nm) as an intermediate. The kinetic parameters for the ylide formation and further 1,5-intramolecular cyclization to the pyrrole ring have been determined. (C) 1999 Elsevier Science Ltd. All rights reserved.