The synthesis of a series of bicyclic nucleosides using photolytic ring-expansion of cyclobutanones is reported. The cyclobutanone precursors were prepared by [2+ 2] cycloaddition of a series of cyclic alkenes with chlorinated ketenes, derived from dichloro- and trichloroacetyl chloride. The synthesis of the nucleosides was achieved through photolysis of cyclobutanone precursors with 6-chloropurine by UV irradiation. The ...