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We wish to report the generation and chemistry of the heretofore unknown (2-alkynylethenyl)ketenes, specifically those of general structure 2. Such compounds are accessible from the corresponding alkynylcyclobutenones 1. The ketenes thus generated are envisaged to undergo ring closure to the unique zwitterions 3 and 4 and these, in turn, proceed to products 5 and 6 via transfer of the trimethylsilyl group.1 Significantly, the formation of 5 constitutes a new and potentially general quinone synthesis.

It has been shown by Bohlmann et al.la that plants of the genus Anthemis contain a variety of compounds with the thio enyne fragment 1. It is well established that this 1 structural element with cis geometry around the double bond is formed exclusively in the ring-opening of 3-thienyllithium derivatives.2 This suggested to us that the (1) (a) Bohlmann, F.;

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