The title carbenes, which in principle can all serve as precursors to the reactive hydrocarbon pseudoindene, have been generated by the photolysis of the sodium salts of the tosylhydrazones of (a) benzocyclobutene-1-carboxaldehyde, (b) 2-methylbenzocyclobutenone and (c) o-formylstyrene. Indene was formed in reactions (a) and (c): in the former case deuterium labelling experiments suggest a ring expansion