THE 1-PHOSPHAALLYL ANION AS A VERSATILE BUILDING-BLOCK IN REACTIONS WITH ALKYNES AND FISCHER-TYPE ALKYNYLTUNGSTEN CARBENE COMPLEXES

The anionic 1,3-cycloaddition reaction of the (1,2,3-triphenyl-1-phosp haallyl)lithium species Li(dme)(3)[Php-Cph=C(ph)H] (1) with diphenylac etylene followed by protonation of the anionic intermediate 2 gave dia stereo selectively 1,2,3,4,5-pentaphenyl-2, 3-dihydrophosphole (3). Th e relative cis,trans-stereochemistry of the C4,C5,P-unit has been esta blished by X-ray structure analysis. Addition of 1 to the Fischer-type tungsten amino alkynyl carbene complex (CO)(5)W=C[N(CH2)(4)]-C equiva lent to CPh (4) yielded, after protonation, the metal carbene modified dihydrophosphole 8, which, in contrast, exhibits a trans,trans-diphen yl substitution pattern. Thus, a different reaction pathway is suggest ed, containing an acyclic intermediate, which could be trapped by deut eration to give the (vinylphosphino)vinylcarbene complex (CO)(5)W=C[N( CH2)(4)]-CD=C(Ph)-P(Ph)-CPh=C(Ph)H (10). Thermal decarbonylation of 10 led to the chelate complex (CO)(4)W=C[N(CH2)(4)]-CD=C(Ph)-P(Ph)-CPh=C (Ph)H (11). The reaction of 1 with the tungsten methoxy alkynyl carben e complex (CO)(5)W=C-(OCH3)-C equivalent to C(p-Tol) (5) and subsequen t protonation afforded the acyclic (vinylphosphino)vinyl carbene compl ex (CO)(5)W=C(OCH3)-CH=C(p-Tol)-P(Ph)-CPh=C(Ph)H (9), which underwent rearrangement to the allenyl(vinyl)phosphane complex C(p-Tol)][PhC-C(H )Ph](Ph)P-[W(CO)(5)]Ph-CPh=C(Ph)H (12).