A. Parlier

Unexpected ring opening of cycloaminocarbene complexes of chromium upon alkyne insertion reactions

Abstract Aminocarbenechromium complexes of the general structure (CO)5CrC(R)N-(CH2)nXCH2 (n = 0, X  CH2; n = 1, X  CH2; n = 1, X  CHCH; n = 2, X  molecules of alkyne and one molecule of CO, and CN bond cleavage, new polycyclic heterocycles. The reactions of the pyrroline-, the tetrahydropyridine-, the pyrrolidine- and the methylaziridine-substituted complexes are mainly considered, and the results of X-ray structural studies of the new products are presented. The mechanism of the rearrangement of a 1,5 dipole is discussed.

Heteronuclear (WFe) and homonuclear (FeFE) μ-alkylidene complexes of transition metals from mononuclear terminal carbene complexes. crystal structures of {WFe[μ-η1, η3-C(OCH2CH3)(CHCHCH3](CO)8} and [fe2{μ-η2,η3-C[OCH2CH3[CHC(OCH2CH3)(CH3]}(CO)6

Abstract The reactions of mononuclear carbene complexes of W and Fe of the type CO) m MC(OR)(CH 2 n CHCR′″ (M  = FE, W; m = 4 and 5; n = 0, 2, 3; R′, R″ = C, CH 3 , OEt) with Fe(CO) 5 have been studied. In all cases the reaction leads to new hetero (WFe) or homo (FeFe) μ-alkylidene complexes, the position of the double bond depending strongly on n .

Double acetylene insertion into a μ-methylene complex of iron: formation of a μ-(divinyl)carbene complex of iron after double hydrogen migration

Abstract Acetylene reacts with Fe2[(μ-CH2)(CO)8] to give, besides the known mono-insertion product Fe2{[(μ-CH)(η2-CHCH2)](CO)7} and the linear di-insertion product Fe2{[(μ-CH)-(η4-CHCHCHCH2)][(CO)]6}, the branched μ-divinyl carbene complex Fe2{[(μ-C)(η2-CHCH2)2][(CO)6]}, the formation of which can be accounted for in terms of double hydrogen migration.

Bidentate alkene aminocarbene complexes of chromium: Alkyne insertion with ring expansion versus alkyne insertion with cyclopropanation: Formation and crystal structure of a dihydroazepinechromium tricarbonyl complex

Abstract Whereas (CO) 4 CrC(H)N(CH 3 ) (η 2 -CH 2 CHCH 2 ) ( 3 ) reacts with diphenylacetylene to give the expected azabicyclo[4.1.0]heptene complex ( 6 ), (CO) 4 CrC(CH 3 )N(CH 2 CHCH 2 )(η 2 -NCH 2 CHCH 2 ) ( 12 ) and (CO) 4 CrC(CH 3 )N(CH 2 Ph) (η 2 -CH 2 CHCH 2 ) ( 9 ) give, along with the azabicyclo[4.1.0]heptene complexes, the new dihydroazepine η 3 -Cr(CO) 3 complexes, the complex with a CH 2 Ph group has been fully characterized by X-ray diffraction. A mechanism for the formation of the η 3 complexes is suggested.

Thiocarbene complexes of chromium: sulfur to carbon migration of an allyl group upon alkyne insertion

Abstract (CO)5CrC(CH3)S(CH2CHCH2) (7) reacts with diphenylacetylene by insertion of the alkyne and of CO to give the unsaturated thiolactones H2CCHCH3(CH3)- CSC(O)C(Ph)C Ph and CH3(H) CSC(O)C(PhC Ph, the former arising from migration of the allyl group from sulfur to carbon and the latter by loss of the allyl group.

First intramolecular alkyne–CO insertion reactions in aminocarbene complexes of chromium: formation of condensed heterocycles following extensive hydrogen migrations

The aminocarbene complexes (CO)5CrC(Me)[N(Me)(CH2)3CCPh](6) and (CO)5CrC[graphic omitted][(CH2)3CCMe](14) lead, upon heating in benzene, to the polycyclic triple bond and CO inserted products C15H15NO (12) and C12H15NO (19) through multiple C–H activations.

Dinuclear μ-alkylidene complexes of tungsten from mononuclear, heteroatom-substituted vinyl-alkylidene complexes of this metal

Abstract A general synthesis of homodinuclear μ-alkylidene complexes of tungsten, starting from Fischer type alkylidene complexes of tungsten is outlined. Thus the vinyl-alkylidene complexes (CO) 5 WC(OMe)CHCHR react with (CO) 5 WCPh 2 , as a source of coordinatively unsaturated W(CO) 4 , to give the dinuclear complexes W 2 (CO) 9 (OMe)CHCHR, and the complex (CO) 5 WC(OMe)CHCH 2 reacts slowly in hydrocarbon solution, in the absence of (CO) 5 WCPh 2 , to give a dinuclear complex W 2 (CO) 10 C(OMe)CHCH 2 in which the two metal centers are not bound together: this product is the result of coordination of the double bond of the starting material to a W(CO) 5 species.

Synthesis, X-ray structure and rearrangement of nitrogen ylides obtained upon alkyne and CO insertion reactions into aminocarbene complexes of chromium

The aminocarbene complexes (CO)5CrC(R1)N(R2R3)1[R1= H, Me, Ph, R2= Me, R2R3=(CH2)5, R3= Me, cyclopropyl] react with diphenylacetylene to give nitrogen ylides 5 which were fully characterized by an X-ray analysis carried out on 5a[(CO)3CrR2R3N(C16H10OR1)–(R1= H, R2= R3=(CH2)5] and which lead, upon nitrogen to carbon migrations of alkyl groups R2 and R3, to the expected lactams (e.g.8 and 9) C16H10ONR1R2R3.

Reaction of N-methyldihydropyridines with alkoxycarbene complexes of chromium and tungsten: sequential use of three carbonyl ligands of Cr(CO)6 for the formation of polyoxygenated compounds

N-methylpyridinium ylide complexes obtained from alkoxycarbene complexes of chromium and N-methyldihydropyridines easily insert successively a CO ligand to give α-alkoxy chromium acyl complexes, then a tethered triple bond and two additional CO groups to yield bicyclic butenolides.

A new reaction of aminocarbene complexes of chromium upon alkyne insertions: deoxygenation rearrangement of ketene intermediates. Formation and X-ray structure of a tetrahydroindolizine complex

Aminocarbene complexes (1) of chromium bearing suitable substituents on nitrogen react with alkynes to give, besides the expected heterocyclic compounds (5) and (6) originating from cascade alkyne–CO insertion–rearrangement reactions, deoxygenation–rearrangement products (8) of ketene intermediates, whereas when nitrogen bears substituents of low migratory aptitude, ketene complexes (4) and their derivatives (7) could be isolated and fully characterized either by spectroscopy or by X-ray Crystallography.