2-(Acyloxy)ethenyl)carbene complexes (CO)5M=C(OEt)-CH=C(OCOR)Ph [(Z)-5] (M = Cr, W; R = Ph, p-Me2NC6H4, CH3) c-C7H7CH2, PhCH=CPh, Me2C=CH, 1,4-C6H4) are obtained by the addition of carboxylic acids R-C02H (4) to alkynylcarbene complexes (CO)sM=C-(OEt)-C=CPh (1) (M = Cr, W) in the presence of Et3N at 20 °C in 71-78% isolated yields. The reaction is regio-and stereochemically uniform. (Z)-5g (R = PhCH=CPh), C3iH220eW, was characterized by X-ray diffraction. It crystallizes in space group PI with cell parameters a = 10.381(6) Á, b = 11.444(6) Á, c = 13.509(7) Á, a = 107.84(4)°, ß = 91.54(4)°, = 108.49-(4)°, Z = 2, Ri = 0.0354, and wR2 = 0.0811. Ligand disengagement from (Z)-5 with tertbutyl isocyanide (8b) at 20 °C results in the formation of [2-(acyloxy)ethenyl]ketene imines i-BuN=C=C(OEt)-CH=C(OCOR)Ph [(Z)-ll] (>95% yields).Alkenylcarbene complexes (CO)sM=C-C=C of chromium and tungsten have gained much interest recently as C3 building blocks for the synthesis of car-bocyclic2 and heterocyclic3 rings. Though this class of compounds has been known since 1967,4 systematic studies have been initiated only recently. Complexes (CO)sM=C-C=C(OR1) of types A and B deserve particular attention due to their structural relationship to ß-keto ester equivalents of the enol ether (R1 = alkyl) and enol ester type (R1 = acyl), respectively (Chart 1). Enol Ethers 3Complexes (CO)5M=C-C=C[0(alkyl)] (M = Cr, W) of the enol ether type are accessible by several methods (Scheme 1): (a) by the condensation of methylcarbene complexes (CO)5M=C(OEt)CH3 with dimethylformamide or other nonenolizable acid amides R1-CONR2 (eq l),5

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.

Synthesis and Crystal Structure of a Novel Hexagonal Modification of Al2S3 with Five-Coordinated Aluminum.-The novel HTmodification of Al2S3, obtained by chemical transportation with I2 in a temp. gradient (860 → 750 • C) or by annealing of α-Al2S3 at ¿ 550 • C, belongs to the hexagonal space group P61, Z = 6. In its structure, which is isotypic to those of In2Se3 and AlInS3, 50% of the Al atoms are tetrahedrally coordinated, whereas the other 50% are in trigonal bipyramidal coordination (AlS4 and AlS5 polyhedra). This is the first observation of an AlS5 coordination polyhedron. -(KREBS, B.; SCHIEMANN, A.; LAEGE, M.; Z.

Organic Syntheses via Transition Metal Complexes. Part 67. Metathesis of Enamines by Alkynylcarbene Tungsten Complexes. Formation of Aminobenzenes via Pyranylidene Complexes. -Addition reaction of the enamines (I) and the alkynylcarbene complex ( II) forms the intermediate open-chain carbene complexes (III) which undergo ring closure in solution to give the pyranylidene complexes ( IV). These release tungsten hexacarbonyl to produce the 1,3,5-trisubstituted aminobenzenes (V). -(AUMANN, R.; ROTHS, K.; LAEGE, M.; KREBS, B.; Synlett (1993) 9, 667-669; Org.-Chem. Inst., Univ., 48149 Muenster, Germany; EN)

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