Dynamic Chirality of (E)-5-Cyclononen-1-one and its Enolate
摘要:
It has been found that (E)-5-cyclononen-1-one (2a) exhibits marginal planar chirality owing to an insufficient topological constraint, whereas the enolates 3 derived from 2a show robust planar chirality. Enantioenriched enolates are easily prepared by enzymatic hydrolysis, and they show an ability to serve as chiral nucleophiles.
Dynamic Chirality of (E)-5-Cyclononen-1-one and its Enolate
摘要:
It has been found that (E)-5-cyclononen-1-one (2a) exhibits marginal planar chirality owing to an insufficient topological constraint, whereas the enolates 3 derived from 2a show robust planar chirality. Enantioenriched enolates are easily prepared by enzymatic hydrolysis, and they show an ability to serve as chiral nucleophiles.
Medium sized trans-cycloalkenes are unusually reactive in the intermolecular Pauson-Khand reaction (PKR) with regard to typical monocyclic alkenes. This is due to the ring strain imparted by the E stereochemistry. The PKR of these alkenes offers a modular, regioselective and straightforward entry to trans fused [n.3.0] bicyclic scaffolds (n = 6-8).
Synthesis and Stereochemical Behavior of (<i>E</i>)-Cyclononene Derivatives
作者:Katsuhiko Tomooka、Hiroko Inoue、Kazunobu Igawa
DOI:10.1246/cl.2011.591
日期:2011.6.5
A versatile synthetic approach to planar chiral molecules from (E)-5-cyclononen-1-one (1) has been developed; these molecules have multifunctionalities with (E)-cyclononene skeleton. The newly synthesized keto-ester 3 having central chirality shows labile planar chirality. In contrast, enol derivative 4 and enyne 5 show robust planar chirality.
2-chlorocycloalkanones with vinylmagnesium chloride gives 1,2-divinylcycloalkanols. Divinylation proceeds via a rearrangement of initially formed 2-chloro-1-vinylcycloalkanols to 2-vinylcycloalkanones followed by further vinylation of 2-vinylcycloalkanones. Thermal sigmatropic rearrangement of 1,2-divinylcycloalkanols gives 5-cycloalken-1-ones in good yields. The influence of the size of rings on the
Carbocyclic ring expansion reactiuon VIA radical chain processes
作者:Jack E. Baldwin、Robert M. Adlington、Jeremy Robertson
DOI:10.1016/0040-4020(89)80003-1
日期:1989.1
Palladium-mediated transannular cyclizations of medium-ring olefinic enolsilanes
作者:Andrew S. Kende、Clara E. Mota Nelson、Sébastien Fuchs
DOI:10.1016/j.tetlet.2005.09.125
日期:2005.11
Medium-ring olefinic ketone and lactone enolsilanes were subjected to palladium(II)-mediated cycloalkenylation conditions. Diverse bicyclic ring products were obtained in moderate to good yields. The effect of olefin geometry and ring size is discussed. (c) 2005 Elsevier Ltd. All rights reserved.