Aluminum Chloride-Mediated Acylation of Methylenecyclobutanes. A Facile Synthetic Protocol for the Construction of Substituted Cyclopentenes
摘要:
Reactions of methylenecyclobutanes (MCBs) with acyl chlorides produce the corresponding substituted cyclopentene derivatives in moderate to high yields via ring enlargement in the presence of aluminum chloride under mild conditions. A plausible mechanism has been proposed on the basis of control and deuterium labeling experiments.
[3+2] Cycloaddition Reaction of Cyclopropyl Ketones with Alkynes Catalyzed by Nickel/Dimethylaluminum Chloride
作者:Takashi Tamaki、Masato Ohashi、Sensuke Ogoshi
DOI:10.1002/anie.201106174
日期:2011.12.9
[3+2] cycloaddition between the title compounds gives cyclopentene derivatives in the presence of Me2AlCl. The organoaluminum reagent activates the carbonylgroup of the cyclopropyl ketone through coordination of the oxygen atom to the aluminum, and stabilizes the reaction intermediate by the coordination of the chloride to nickel. cod=1,5‐cyclooctadiene, THF=tetrahydrofuran.
diketones and alkenes under cobalt(II) catalysis and dimethyl sulfoxide involvement. Under optimal conditions, the formation of five- and six-membered rings can be readily controlled by the α-position substitution of styrenes. This process is proposed to proceed through a reaction sequence of oxidative coupling (mediated by K2S2O8), regioselective alkene insertion (promoted by cobalt), and intramolecular
通过在钴 (II) 催化和二甲亚砜参与下偶联二酮和烯烃,实现了一种合成环戊烯和环己烯的独特方法。在最佳条件下,五元环和六元环的形成可以很容易地通过苯乙烯的α位取代来控制。建议该过程通过氧化偶联(由 K 2 S 2 O 8介导)、区域选择性烯烃插入(由钴促进)和所得烯丙基钴物质对羰基或甲基进行分子内攻击的反应序列进行。反应亚甲基工艺。