Reactions of transition-metal η1-propargyl complexes with sulfur dioxide and sulfur trioxide: transition-metal–carbon bond cleaving reactions of the cycloadducts which yield 1,2-oxathiole-2-oxides and -2,2-dioxides

The preparation of several cyclopentadienyl iron dicarbonyl and triphenylphosphine manganese tetracarbonyl η1-2-alkynyl complexes are reported. The [3+2] cycloaddition reactions of these complexes with sulfur dioxide and sulfur trioxide yielded transition-metal substituted 1,2-oxathiolene-2-oxides and 1,2-oxathiolene-2,2-dioxides, respectively. One of the η1-propargyl complex SO3 cycloadducts has been characterized by X-ray crystallography. The transition metal can subsequently be cleaved from the oxathiole-oxide and dioxide containing complexes to produce a variety of new sulfur containing heterocycles.