multi‐substituted N‐methoxyamines from N‐methoxyamides is reported. Utilization of the N‐methoxy group as a reactivity control element was the key to success in this two‐step synthesis. The first reaction involves a N‐methoxyamide/aldehyde coupling reaction. Whereas ordinary amides cannot condense with aldehydes intermolecularly due to the poor nucleophilicity of the amide nitrogen, the N‐methoxy group
The application of cyclic and acyclic enol ethers as electrophiles in cross coupling reactions offers new possibilities for the preparation of functional compounds.
环状和非环状烯醇醚作为亲电试剂在交叉偶联反应中的应用为功能化合物的制备提供了新的可能性。
BF<sub>3</sub>-Catalyzed Reaction of Cyclobutene-1,2-dione Monoacetal and Its Vinylog with Allylsilanes. Regioselective Synthesis of 4-Allyl-4-ethoxycyclobutenones from Squaric Acid and Their Conversion to Bi- and Tricycloalkanones
作者:Yoshihiko Yamamoto、Masatomi Ohno、Shoji Eguchi
DOI:10.1246/cl.1995.525
日期:1995.7
Regioselective allylation of 2,4- and 4,4-diethoxycyclobutenones was performed with allylsilanes in the presence of BF3•Et2O via a common ethoxycarbenium ion intermediate. A merit of this reaction was demonstrated in an efficient conversion of the obtained 4-allyl-4-ethoxycyclobutenones to bi- and tricycloalkanones.
Vicinal tricarbonyls in synthesis. New routes to indolizidines.
作者:Harry H. Wasserman、Chi B. Vu、Jan D. Cook
DOI:10.1016/s0040-4020(01)88877-3
日期:——
The vinylvicinaltricarbonyl system 1 (VTC) has been used in two different approaches to prepare functionalized indolizidines. In one approach, 1 is used as a trielectrophile in reactions with primary amines possessing auxiliary donor sites. In a second approach, 1 is converted to a substituted 3-hydroxypyrrole-2-carboxylate. This pyrrole derivative then undergoes an intramolecular alkylation to give
The Lewis acid-catalyzed intramolecularsubstitutionreactions of 4-vinyloxy- or 4-acyloxy-azetidin-2-ones with nitrogen-bound allyl-, propargyl- and vinyl-silanes leading to the carbacephams or carbacephems, are reported. The formation of carbapenams was not observed. To illustrate the potential of these reactions to be carried out under solid-phase conditions, a synthesis of diastereomeric 5-vinyl-carbacephams