[2#pi# + 2#sigma#] and [8#pi# + 2#sigma#] types Cycloaddition Reactions of Aza-, Thio-, and Thiaza-Azulen-2(1H)-one Derivatives with Naphtho[b]Cyclopropene: Effects of Solvents and Ytterbium Complex

摘要

Reactions of naphtho[b]cyclopropene with 1-aza- or 1-thiaazulene-2(1H)-one derivatives in choroform under the presence of a catalytic amount of ytterbium complex afforded [2#pi# + 2#sigma#] type cycloaddition products. The analogous reactions of the cyclopropene with a 1-thia-3-azaazulene-2(1H)-one derivative gave an [8#pi# + 2#sigma#] type cycloadduct. These reactions were considered to proceed via ionic proceses, in which the azulene-2(1H)-one derivativees played as 2#pi# and 8#pi# comoponents, respectively. On the other hand, reactions of the cyclopropene with 1-azaazulene-2(1H)-one derivatives in benzene yielded the another type of [8#pi# + 2#sigma#] type cycloadducts via a concerted process.