1-Phospha- and 1-Aza-3-Phosphaallylic Anions

The 1-Phosphaallyl Anion as a Versatile Building Block in Reactions with Alkynes and Fischer-Type Alkynyltungsten Carbene Complexes

“…The resulting anionic intermediate ( A ) is supposed to undergo cyclization, and subsequent protonation of the anionic five-membered phosphorus heterocycle 6 is expected to result in the formation of the metal carbene functionalized 2,3- trans -diphenyldihydrophosphole 8 (Scheme ). In contrast, the formation of the 2,3- cis -diphenyldihydrophosphole 3 , has been explained by a concerted cycloaddition of the 1,3-dipolar 1-phosphaallyl anion to the diphenylacetylene followed by a formal 1,3-hydrogen shift and subsequent protonation 3a 3 Mechanism of the Reaction of 1 with the Carbene Complexes 4 and 5 …”

“…Silica gel (Merck, 0.063−0.200 mm) was degassed in a high vacuum and stored under argon. 1,2,3-Triphenyl-1-phosphaallyllithium, 1,2,3,4,5-pentaphenyl-2,3-dihydrophosphole,3a pentacarbonyl[(phenylethynyl)( N -pyrrolidino)carbene]tungsten(0) and pentacarbonyl[((p-tolyl)ethynyl)(methoxy)carbene]tungsten(0) were prepared according to procedures described in the literature. All chemical shifts are reported in parts per million.…”

“…Subsequent protonation by the mild carbon acid phenylacetylene yielded the 2,3-dihydrophosphole 3 (Scheme ). Since both the cycloaddition and the protonation step are diastereoselective, this reaction sequence offers a stereocontrolled route to densely-substituted dihydrophospholes …”