Organic Syntheses via Transition Metal Complexes. 73. Acylation of Metalcarbene Complexes (M = Cr, W) with Formation of (2-(Acyloxy)ethenyl)-, (4-(Acyloxy)butadienyl)-, and Alkynylcarbene Complexes

Abstract

2-(Acyloxy)ethenyl]carbene complexes (CO)sM=C(OEt)-CH=C(OCOR)R [(2)-41 (R = t-Bu, i-Pr, c-Pr, Ph, p-tolyl, p-anisyl) are obtained by acylation of methylcarbene complexes (C0)5M=C(OEt)CH3 (1) (M = Cr, W) with carboxylic acid chlorides R-COCl(2) (R = t-Bu, LPr, c-Pr, Ph, p-tolyl, p-anisyl, o-CsH&OCl) in the presence of Et3N in 53-78% isolated yields, Side reactions include the formation of nonconjugated alkenylcarbene complexes (CO)&=C(OEt)-CH2-C(OCOZPr)=CMe2 (Sb,h) (R = i-Pr) and of alkynylcarbene complexes (C0)5M=C(OEt)-CWR (6a,g,i) (R = t-Bu, c-Pr). The tungsten complexes (2)-4d-f (R = aryl) undergo a metathesis to give (4-(acyloxy)butadienyl)carbene complexes (CO)sW=C-(0Et)-CH=C(OEt)-CH=C(OCOR)R [(E,2)-7d-fl. (E,2)-7f (R = p-anisyl) was characterized by X-ray diffraction. It crystallizes in space group Pi with cell parameters a = 9.696(2) A, b = 11.751(2) A, c = 13.909(3) A, a = 100.79(2)", B = 93.06(2)", y = 102.90(1)", 2 = 2, R1 = 0.0345, and wR2 = 0.0770.[2-(Acyloxy) e thenyll carbene Complexes (2) -4 Protons attached to the a-carbon atom of methylcarbene complexes (C0)5M=C(OEt)CH3 (1) [M = Cr (a), W (b)l undergo a rapid base-catalyzed hydrogen/ deuterium exchange2 and are easily replaced also by many other ele~trophiles.~ Recent studies include basecatalyzed condensations with acid amide^^,^ O=C(NR& R' to give (2-aminoetheny1)carbene complexes (CO)&I=C-(OEt)-CH=C(NR2)R', as well as substitution reactions with cationic olefin c~m p l e x e s ,~~~ tropylium ions,* and complexed cyclohexadienyl-or cycloheptadienyl cation^,^ which yield a-mono-as well as a-disubstituted meth-@ Abstract published in Aduance ACS Abstracts, July 1, 1994. (1) Part 72: Aumann, R.; Jasper, B.; Lage, M.; Krebs, B. Organometallics, preceding article in this issue. Parlier, A.; Rose-Munch, F.; Rudler, H.; Daran, J. C.; Knobler, C.; Jeannin, Y. J.

1-Metalla-1,3,5-hexatrienes and Related Compounds

“…2,5-Diethoxy-1,6-dimetalla-1,3,5-hexatrienes by oxida-6-acyloxy-2,4-diethoxy-1-tungsta-1,3,5-hexatrienes tive coupling of (methyl)carbene complexes (Scheme 10). [15] Dinuclear dimetallahexatrienes, e.g. 2,5-diethoxy-1,6-dimetalla-1,3,5-hexatrienes have been produced by oxidative coupling of two molecules of (methyl)carbene complexes with AgBF 4 and oxidation of the resulting CϪC single bond in "reversed order" to that applied in Scheme 6, namely by H ϩ /H Ϫ abstraction with (1) nBuLi and (2) AgBF 4 (Scheme 7).…”

Organic Syntheses via Transition Metal Complexes. 89.1 5-Aza-1-metalla-1,3,5,7-octatetraenes and 2H-Pyrrole and 2H-Dihydroazete Complexes from (1-Alkynyl)carbene Complexes (M = Cr, W) and Alkenyl N-H Imidates

“…The plane defined by the atoms attached to the carbene carbon atom of 9b bisects the angle between two neighboring cis carbonyl groups, C(21)−W−C(4)−C(5) = 49.4(0.4)°. The WCCCNCCC backbone of the ligand displays the alternating bond pattern W−C(4) = 2.215(5) Å, C(4)−C(5) = 1.436(6) Å, C(5)−C(6) = 1.374(6) Å, C(6)−N(7) = 1.375(6) Å, N(7)−C(8) = 1.269(6) Å, C(8)−C(12) = 1.452(7) Å, and C(12)−C(13) = 1.312(8) Å, similar to that found for 2-alkoxy-1-tungsta-1,3,5-hexatrienes . The WCCC and NCCC portions of the ligand are essentially planar (W−C(4)−C(5)−C(6) = −165.2(0.4)°, N(7)−C(8)−C(12)−C(13) = 179.6(0.6)°) but strongly distorted against each other (C(5)−C(6)−N(7)−C(8) = −83.7(0.7)°).…”

Organic Syntheses via Transition Metal Complexes. 118.1 Retro-Fischer Reaction Induced by a β-Imino Functionality of (Alkyl,ethoxy)carbene Complexes (M = W, Cr): Efficient Access to C-Enamino and N-Enamino Carbene Complexes

“…On the basis of earlier studies, in which 1-metalla-1,3-butadienes (CO) 5 MC(OEt)CHCHR and (CO) 5 MC(OEt)CHC(NR 2 )R 1 were obtained by condensation of (ethoxy,methyl)carbene complexes (CO) 5 MC(OEt)CH 3 1a , b (M = W, Cr) with aldehydes and ketones, , acid chlorides, and acid amides, respectively, we succeeded in obtaining vinylogous systems, like 4-amino-1-metalla-1,3,5-hexatrienes by condensation of compounds 1a , b with α,β-unsaturated tertiary acid amides PhCHCHC(O)NR 2 . In line with expectation, these compounds underwent a π-cyclization to zwitterionic η 1 -cyclopentadiene complexes (Scheme ).…”