Synthesis of unsaturated lactones via palladium-catalyzed cyclization of alkenoic acids
摘要:
Acyclic and cyclic, aliphatic or aromatic, 4- or 5-alkenoic acids cyclize in high yield to 5- or 6-membered unsaturated lactones using 5 mol % Pd (OAc) 2, 2 equiv of NaOAc, and 1 atm Of O2.
Highly Regio- and Stereoselective Ring-Opening Reaction of γ-Alkenyl-γ-butyrolactones with Allylsilanes in the Presence of Trimethyloxonium Salt Leading to Methyl 4,8-Alkadienoates
作者:Masatoshi Kawashima、Tamotsu Fujisawa
DOI:10.1246/bcsj.61.4051
日期:1988.11
The reaction of γ-alkenyl-γ-butyrolactones with allylic trimethylsilanes in the presence of trimethyloxonium tetrafluoroborate proceeded regio- and stereoselectively with an allylic rearrangement of the substrate to afford methyl (E)-4,8-alkadienoates in high yields. On the other hand, the ring opening of 4-hexen-6-olide afforded exclusively methyl (Z)-4,8-alkadienoates in high yields. The synthetic utility of the reaction was demonstrated by the short step synthesis of β-sinensal and β-farnesene.
A Facile Method for the Preparation of γ-Alkenyl-γ-butyrolactones
作者:Masatoshi Kawashima、Tamotsu Fujisawa
DOI:10.1246/bcsj.61.3377
日期:1988.9
Methyl substituted γ-alkenyl-γ-butyrolactones were prepared from easily available α,β-unsaturated aldehydes such as acrylaldehyde, methacrylaldehyde, crotonaldehyde, and 3-methyl-2-butenal.
Chiral <i>N</i>-Alkyl-2,4,6-triphenylpyridiniums as Enantioselective Triplet Photosensitizers. Laser Flash Photolysis and Preparative Studies
作者:Mercedes Álvaro、Pilar Formentín、Hermenegildo García、Emilio Palomares、María J. Sabater
DOI:10.1021/jo020113w
日期:2002.7.1
Three N-alkylpyridinium photosensitizers having chiral alkyl groups have been prepared by reacting 2,4,6-triphenylpyrylium tetrafluoroborate ion with (1R,2S)-(-)-norephedrine, (S)-(+)-2-(aminomethyl)pyrrolidine, and (R)-(-)-1-cyclohexylethylamine. Laser flashphotolysis allows detection of the corresponding triplet excited states that are quenched by hydrogen atom donors and electron donors. Asymmetric
Use of sterically hindered sensitizers for improved photoinduced electron-transfer reactions
作者:Paul G. Gassman、Saliya A. De Silva
DOI:10.1021/ja00026a034
日期:1991.12
Increasing both product yields and quantum yields can be accomplished throuth the use of sterically encumbered photosensitizers. The anti-Markovnikov lactonization of 5-methyl-4-hexenoic acid, a photoinduced SET reaction was chosen as the model reaction for the evaluation of a series of sensitizers.
可以通过使用空间位阻光敏剂来提高产品产率和量子产率。选择 5-甲基-4-己烯酸的抗马尔科夫尼科夫内酯化,一种光诱导的 SET 反应作为评估一系列敏化剂的模型反应。
Highly regio- and stereoselective ring-opening reaction of γ-alkenyl-γ-butyrolactones using allylsilanes-trimethyloxonium salt to afford methyl (e)-4,8-alkadienoates