Hydroxyacetylene-ketene isomerization

Neither ground-state ethynol (hydroxyacetylene) (80) nor carbenaoxirane (81) appears to be a viable point of ingress to the oxirene-methanoylcarbene system, as both can isomerize to ketene by lower-energy pathways. The limited experimental information available on carbenaoxirane (Section 5.05.6.3.4(f/)) indicates that it is indeed largely isolated from the oxirene-methanoylcarbene manifold (but note the photolysis of ketene in Section 5.5.6.3.4(ff)) appropriate labelling experiments with (the unknown) ethynol have not been performed. 

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