Preparation and properties of some thiouronium fluorenylides and cyclopentadienylides and the attempted preparation of selenouronium and guanidinium fluorenylides

Some stable thiouronium fluorenylides and cyelopentadienylides, prepared by treatment of the corresponding thiouronium salts with non-aqueous base, exist as tautomeric mixtures of the fluorenylide and fluorenylisothiourea, but undergo reactions typical of ylides, e.g. Wittig reactions with aldehydes or nitrosobenzene; a 2,3,4-triphenylcyclopentadienylide gave anomalous products. The ylides also react with acids, alkali, benzyl bromide, and dimethylacetylene dicarboxylate. N,N'-Diphenyl-selenouronium and -guanidinium analogues appear to exist entirely as the non-ylidic tautomers.