Domino syntheses of five-, six- and seven-membered O-, N- and S-heterocycles from α-, β- and γ-substituted carboxylic esters
摘要:
By a one-pot procedure, tetronic acids, tetronates, coumarins, benzoxepinones and their N- and S-analogues are readily accessible from keteneylidene(triphenyl)phosphorane 2 and carboxylic esters bearing OH, NHR or SH groups in an alpha-, beta- or gamma-position by an addition/Wittig olefination/(Claisen rearrangement) sequence. This cascade can be controlled by temperature variation. Extension of this procedure by a further addition step yielding annulated bisheterocycles such as the furoquinolone 28 is possible in some cases.
Domino syntheses of five-, six- and seven-membered O-, N- and S-heterocycles from α-, β- and γ-substituted carboxylic esters
作者:J. Löffler、R. Schobert
DOI:10.1039/p19960002799
日期:——
By a one-pot procedure, tetronic acids, tetronates, coumarins, benzoxepinones and their N- and S-analogues are readily accessible from keteneylidene(triphenyl)phosphorane 2 and carboxylic esters bearing OH, NHR or SH groups in an alpha-, beta- or gamma-position by an addition/Wittig olefination/(Claisen rearrangement) sequence. This cascade can be controlled by temperature variation. Extension of this procedure by a further addition step yielding annulated bisheterocycles such as the furoquinolone 28 is possible in some cases.
Stereoselective Synthesis of Pyrrolidine Derivatives via Reduction of Substituted Pyrroles
作者:Chao Jiang、Alison J. Frontier
DOI:10.1021/ol701962w
日期:2007.11.1
hydrogenation of highly substituted pyrrole systems was studied. These aromatic systems could be fully reduced with excellent diastereoselectivity to afford functionalized pyrrolidines with up to four new stereocenters. It is likely that the reaction is a two-step hydrogenation sequence, and that initial reduction of the C=X bond provides a stereocenter that directs the subsequent reduction of the pyrrole.