Catalytic Intramolecular Wittig Reaction Based on a Phosphine/Phosphine Oxide Catalytic Cycle for the Synthesis of Heterocycles.

The catalytic intramolecular Wittig reactions of carbonyl-containing bromides are reported. The R₃PO byproducts participate in the catalytic cycle; therefore, the Wittig reaction can be accomplished with only a catalytic amount of organophosphorus reagent. The reaction has also been applied to the efficient and selective synthesis of isoquinolin-1(2H)-ones, indoles, 2,3-dihydro-1H-2-benzazepin-1-ones, benzofurans, and 1,2-dihydroquinolines with a catalytic amount of phosphine oxide (0.1 equiv.) and a tetramethyldisiloxane/titanium isopropoxide [TMDS/Ti(OiPr)₄] reductant system (yields: 35-88 %). [ABSTRACT FROM AUTHOR]