Copper-Catalyzed Intermolecular Oxidative [3 + 2] Cycloaddition between Alkenes and Anhydrides: A New Synthetic Approach to γ-Lactones
作者:Liangbin Huang、Huanfeng Jiang、Chaorong Qi、Xiaohang Liu
DOI:10.1021/ja108073k
日期:2010.12.22
A new copper-catalyzed oxidative [3 + 2] cycloaddition of alkenes with anhydrides using oxygen as the sole oxidant to afford γ-lactones has been developed. This catalyzed cyclization process has a broad substrate scope and affords γ-lactones in good to excellent yields.
methylmalonic acid with mono- and disubstituted olefins in the presence of manganese(III) acetate yielded 2-carboxy-2-methyl-4-butanolides in moderate to good yields. The reactions of bromomalonic acid and chloromalonic acid with a variety of olefins gave 2-halo-4-butanolides and/or 2-buten-4-olides. The reaction of ethyl hydrogen malonate with olefins in the presence of manganese(III) acetate yielded
An abundant and low toxicity iron catalyst has enabled regioselective annulation of alkenes with α-halocarboxylic acids and their derivatives. The reaction proceeds smoothly without any additional ligands, bases, and additives to afford a variety of γ-lactones in good yields. A proposed reaction pathway through radical annulation is supported by some mechanistic studies, involving radical clock and
A stereoselective, tandem [2+2] photocycloaddition–hydrolysis route to aldol-type adducts
作者:Manabu Abe、Masayuki Ikeda、Masatomo Nojima
DOI:10.1039/a805404e
日期:——
Photocycloadditions of aromatic aldehydes 2aâe with cyclic ketene silyl acetals 1aâe have been investigated. Regio- and exo-selective formation of the bicyclic 2-alkoxyoxetanes 3 was observed in high yields. Hydrolysis of the acid-labile oxetanes 3 with neutral water was efficiently achieved to give aldol-type adducts 4 (threo-selective formations).
Intramolecular Nucleophilic Acyl Substitution Reactions Mediated by XTi(O-<i>i</i>-Pr)<sub>3</sub> (X = Cl, O-<i>i</i>-Pr)/2<i>i-</i>PrMgBr Reagent. Efficient Synthesis of Functionalized Organotitanium Compounds from Unsaturated Compounds
作者:Sentaro Okamoto、Aleksandr Kasatkin、P. K. Zubaidha、Fumie Sato
DOI:10.1021/ja953497z
日期:1996.1.1
readily generated by the reaction of Ti(O-i-Pr)4 or ClTi(O-i-Pr)3 with 2i-PrMgX, resulted in an intramolecular nucleophilic acyl substitution (INAS) reaction to afford organotitanium compounds having a carbonyl functional group, in good to excellent yields. Thus, the treatment of alkyl alkynyl carbonates 2 or alkyl alkenyl carbonates 4 with 1 gave organotitanium compounds having a lactone and/or ester