Diene-Transmissive Hetero Diels–Alder Reactions of 3-Oxo-1,4-pentadiene Equivalents Leading to Functionalized 2-Chromanones
作者:Eiji Wada、Shuji Kanemasa、Otohiko Tsuge
DOI:10.1246/bcsj.62.1198
日期:1989.4.15
Through hetero Diels–Alder reaction with a vinyl ether and Horner–Emmons olefination, diethyl 2-oxo-3-butenylphosphonate leads to 2-ethoxy-6-(1-alkenyl)-3,4-dihydro-2H-pyrans which are further transformed into 2-chromanones via regioselective Diels–Alder reactions with activated acetylenes followed by hydrolysis and oxidation.
Brønsted and Lewis acid sites in zeolites were characterized by using 2-quinolone as a probe, by means of ultraviolet and infrared absorption spectra, fluorescence decay lifetime, and ESR. The results showed clearer differences in the acidity of zeolites compared to those determined by using Hammett indicators. The species observed in the zeolites depended on the acidity, the cavity size, and the amount of 2-quinolone loaded.
New Synthesis of 2-Oxo-3-alkenylphosphonates and Hetero Diels–Alder Reactions with Vinyl Ethers Leading to 5-Substituted 2-Phosphiny 1-2-cyclohexen-1-ones
作者:Eiji Wada、Shuji Kanemasa、Otohiko Tsuge
DOI:10.1246/bcsj.62.860
日期:1989.3
A new method of synthesizing phosphinyl-substituted enones, 2-oxo-3-alkenylphosphonates, is developed via the dianion of diethyl 2-oxopropylphosphonate. The enones serve as hetero dienes in thermal reactions with vinly ethers producing 2-alkoxy-6-(phosphinylmethyl)-3,4-dihydro-2H-pyrans. Acid-catalyzed cleavage of these cycloadducts is followed spontaneously by internal condensation furnishing 2-p