ORGANIC SYNTHESES VIA TRANSITION-METAL COMPLEXES .73. ACYLATION OF METHYLCARBENE COMPLEXES (M=CR, W) WITH FORMATION OF [2-(ACYLOXY)ETHENYL]CARBENE, [4-(ACYLOXY)BUTADIENYL]CARBENE, AND ALKYNYLCARBENE COMPLEXES

[2-(Acyloxy)ethenyl]carbene complexes (CO)(5)M=C(OEt)-CH=C(OCOR)R [(Z)-4] (R = t-Bu, i-Pr, c-Pr, Ph, p-tolyl, p-anisyl) are obtained by acylation of methylcarbene complexes (CO)(5)M=C(OEt)CH3 (1) (M = Cr, W) with carboxylic acid chlorides R-COCl (2) (R = t-Bu, i-Pr, c-Pr, Ph, p-tolyl, p-anisyl, o-C6H4COCl) in the presence of Et(3)N in 53-78% isolated yields. Side reactions include the formation of nonconjugated alkenylcarbene complexes (CO)(5)M=C(OEt)-CH2-C(OCOiPr)=CMe(2) (5b,h) (R = i-Pr) and of alkynylcarbene complexes (CO)(5)M=C(OEt)-CH=CR (6a,g,i) (R = t-Bu, c-Pr). The tungsten complexes (Z)-4d-f (R = aryl) undergo a metathesis to give (4-(acyloxy)butadienyl)carbene complexes (CO)(5)W=C(OEt)-CH=C(OEt)-CH=C(OCOR)R (OEt)-CH=C(OEt)-CH=(OCOR)R[(E,Z)7d-f]. (E,Z)-7f(R p-anisyl) was characterized by X-ray diffraction. It crystallizes in space group Pi with cell parameters a 9.696(2) Angstrom, b = 11.751(2) Angstrom c = 13.909(3) Angstrom, alpha = 100.79(2)degrees, beta = 93.06(2)degrees, gamma = 102.90(1)degrees, Z = 2, R(1) = 0.0345, and wR(2) = 0.0770.