A stereoselective synthesis of ω-chlorodienals and ω-chlorodienones was described. Conjugated ω-chlorotrienals and trienones were also easily prepared via an efficient palladium-catalyzed rearrangement of allylic acetates.
Synthesis and Thermal Reactivity of Pyrrolidine- and 2-Pyrrolidinone-Fused Cyclic Enediynes
作者:Amit Basak、Basab Roy
DOI:10.1055/s-2006-950278
日期:2006.10
Various bicyclic enediynes containing pyrrolidine and pyrrolidinone moieties were synthesised. Thermal reactivity studies indicated the lowering of the onset temperature for Bergman cyclisation upon fusion of these heterocyclic systems onto the cyclicenediyne.
A number of N-substituted cyclic enediynes (azaenediynes) have been synthesized via Pd(0)-catalysed ene–yne coupling followed by N-alkylation. The simplest of them, a 10-membered monocyclic enediyne 1, underwent Bergman cyclization (BC) at 23 °C with a half-life of 72 h. The kinetics of BC slowed down considerably by fusing a benzene ring onto the enediyne. Several novel bis(azaenediyne)s and bis(diazaenediyne)s 3–6 have been synthesized. Their onset temperatures for BC were lowered under metal ion complexation conditions.
An Iterative Procedure for the Synthesis of Conjugated ψ-Chlorotrienoic and -tetraenoic Esters and Related Derivatives
作者:Margarita Mladenova、Maya Tavlinova、Momcho Momchev、Mouâd Alami、Michèle Ourévitch、Jean Daniel Brion
DOI:10.1002/ejoc.200300110
日期:2003.7
An iterative stereoselective procedure for the synthesis of isomers of conjugated ψ-chlorotrienoic esters and ψ-chlorotetraenoic esters as well as related conjugated ψ-chloropolyenynoic esters is described, using readily available conjugated chlorodienol and chloroenynol derivatives as starting materials. The two-step sequence studied is based on repetition of a one-pot conjugated allylic alcohol oxidation/Wittig
Treatment of methyl 2-[6-substituted-3(Z)-hexen-1,5 -diynyl]benzoates (1) with five mol% of palladium chloride and three equivalents of cupric chloride in refluxing acetonitrile gave dibenzo[b,d ]pyran-6-ones (2) in modest to good yields.