The unexpected chemistry of a bis(phospholyl)acetylene

The reaction of lithium 3,4-dimethyl-phospholide with tetrachloroethylene gives the corresponding 1,2-bis(phospholyl)acetylene that has been characterized by X-ray crystal structure analysis of its bis(pentacarbonylmolybdenum) complex. The reaction with sulfur leads to the corresponding disulfide that spontaneously undergoes a self-condensation via a Diels--Alder cycloaddition between the CC triple bond and the phosphole dienic system giving, after aromatization by loss of the phosphorus bridge, the corresponding 1,2-bis(phospholyl)benzene. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:537–541, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20457