Fragmentation‐related phosphinylations using 2‐aryl‐2‐phosphabicyclo[2.2.2]oct‐ 5‐ene‐ and ‐octa‐5,7‐diene 2‐oxides

A series of new P-methylphenyl P-heterocycles are introduced. The para and ortho substituted 2,5-dihydro-1H-phosphole oxides (1a and 1b) were converted to the double-bond isomers (A and B) of 1,2-dihydrophosphinine oxides (3a and 3b) via the corresponding phosphabicyclo[3.1.0]hexane oxides (2a or 2b). Isomeric mixture (A and B) of the dihydrophosphinine oxides (3a and 3b) gave, in turn, the isomers (A and B) of phosphabicyclo[2.2.2]oct-5-enes (4a and 4b) or a phosphabicyclo[2.2.2]octa-5,7-diene (5) in Diels-Alder reaction with dienophiles. The bridged P-heterocycles (4 and 5) were useful in the photo- or thermoinduced fragmentation-related phosphinylation of hydroxy compounds and amines. The new precursors (4a and 4b) were applied in mechanistic investigations. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:443–451, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10176

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