[8+2] Cycloadditions of 2,4,6-Cycloheptatriene-1-imines with Chloroketenes: Facile and High-Yield One-Pot Synthesis of 1-Azaazulen-2(1<i>H</i>)-ones
作者:Kazuaki Ito、Katsuhiro Saito、Kensuke Takahashi
DOI:10.1246/bcsj.65.812
日期:1992.3
Simple heating of mixtures of N-arylcycloheptatriene-1-imines and acyl chlorides in the presence of an excess amount of triethylamine afforded 1-azaazulen-2(1H)-ones in high yields. The intermediacy of the [8+2] cycloadducts between the 2,4,6-cycloheptatriene-1-imines and ketenes were confirmed by their isolations. Analogous results were obtained with tropone hydrazones.
Cycloaddition Reactions of Trimethylsilylketene with 8-Azaheptafulvenes and 6-Amino-1-azafulvenes
作者:Toyohiko Aoyama、Kiyo Takaoka、Takayuki Shioiri
DOI:10.3987/com-00-s(i)18
日期:——
.1a,e Reaction of ketenes with 6-amino-1-azafulvenes also proceeds to afford 2,3dihydro-1H-pyrrolizin-3-ones.2b To our knowledge, however, there is no report dealing with reaction of silylketenes, an electron-rich ketene, with azafulvene derivatives. We have already revealed that silylketenes can be effectively used as heterodienophiles for the [4+2] cycloadditionreaction with electron-rich 1,3-dienes
[2p + 2s] and [8p + 2s] Types Cycloaddition Reactions of Aza-, Thio-, and Thiaza-azulen-2(1H)-one Derivatives with Naphtho[b]cyclopropene: Effects of Solvents and Ytterbium Complex
作者:Katsuhiro Saito、Naoko Ito、Shinichi Ando
DOI:10.3987/com-01-s(k)19
日期:——
Reactions of naphtho[b]cyclopropene with 1-aza- or 1-thiaazulene-2(1H)-one derivatives in chloroform under the presence of a catalytic amount of ytterbium complex afforded [2 π + 2 σ] type cycloaddition products. The analogous reactions of the cyclopropene with a 1-thia-3-azaazulene-2(1H)-one derivative gave an [8 π + 2 σ] type cycloadduct. These reactions were considered to proceed via ionic processes