Ene-yne metathesis of polyunsaturated norbornene derivatives

Norbornene derivatives bearing endo-substituents in the 5- and 6-positions were studied as substrates for ene-yne metathesis cascades. Substrates which contained an internal alkyne and a terminal alkene or alkyne in each sidechain were found to undergo a metathesis cascade leading to pentacyclic bis-dienes and bis-trienes. Attempts to extend the chemistry further to sidechains containing two internal alkynes or two internal alkynes and a terminal alkene were not successful with the first generation Grubbs' catalyst. However, the substrate containing two internal alkynes did react with the second generation Grubbs' catalyst to give a tetra-diene containing product.     

Stereochemistry of the insertion of disubstituted alkynes into the metal aminocarbyne bond in diiron complexes

Terminal alkynes (HCCR^′) (R^′=COOMe, CH₂OH) insert into the metal-carbyne bond of the diiron complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCMe)(Cp)₂][SO₃CF₃] (R=Xyl, 1a; CH₂Ph, 1b; Me, 1c; Xyl=2,6-Me₂C₆H₃), affording the corresponding μ-vinyliminium complexes [Fe₂{μ-σ:η³-C(R^′)CHCN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, R^′=COOMe, 2; R=CH₂Ph, R^′=COOMe, 3; R=Me, R^′=COOMe, 4; R=Xyl, R^′=CH₂OH, 5; R=Me, R^′=CH₂OH, 6). The insertion is regiospecific and C-C bond formation selectively occurs between the carbyne carbon and the CH moiety of the alkyne. Disubstituted alkynes (R^′CCR^′) also insert into the metal-carbyne bond leading to the formation of [Fe₂{μ-σ:η³-C(R^′)C(R^′)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R^′=Me, R=Xyl, 8; R^′=Et, R=Xyl, 9; R^′=COOMe, R=Xyl, 10; R^′=COOMe, R=CH₂Ph, 11; R^′=COOMe, R=Me, 12). Complexes 2, 3, 5, 8, 9 and 11, in which the iminium nitrogen is unsymmetrically substituted, give rise to E and/or Z isomers. When iminium substituents are Me and Xyl, the NMR and structural investigations (X-ray structure analysis of 2 and 8) indicate that complexes obtained from terminal alkynes preferentially adopt the E configuration, whereas those derived from internal alkynes are exclusively Z. In complexes 8 and 9, trans and cis isomers have been observed, by NMR spectroscopy, and the structures of trans-8 and cis-8 have been determined by X-ray diffraction studies. Trans to cis isomerization occurs upon heating in THF at reflux temperature. In contrast to the case of HCCR^′, the insertion of 2-hexyne is not regiospecific: both [Fe₂{μ-σ:η³-C(CH₂CH₂CH₃)C(Me)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, 13; R=Me, 15) and [Fe₂{μ-σ:η³-C(Me)C(CH₂CH₂CH₃)CN(Me)(R)}(μ-CO)(CO)(Cp)₂][SO₃CF₃] (R=Xyl, 14, R=Me, 16) are obtained and these compounds are present in solution as a mixture of cis and trans isomers, with predominance of the former.     

Efficient synthesis of [2]- and higher order rotaxanes via the transition metal-catalyzed hydrosilylation of alkyne

A novel end-capping method of pseudorotaxanes via the hydrosilylation of the alkyne of the axle terminal was developed. RuHCl(CO)(PPh₃)₃ and RhCl(CO)(PPh₃)₃ complexes catalyzed the hydrosilylation reactions of the alkyne moiety of several pseudorotaxanes at ambient temperature to give the corresponding [2]- and higher order rotaxanes in high yields with excellent regio- and stereoselectivity.     

Reversible pyranyl complex formation and the mechanism of rearrangement to (η-6-oxocycloheptadienyl)Mn(CO)3 complexes in the reaction of β-cyclomanganated 1,5-diarylpenta-1,4-dien-3-ones and alkynes; the crystal structure of [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η]tricarbonylmanganese

[1-Phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-κO]ethenyl-κC¹]tetracarbonylmanganese (1a) reacts with PhCCH in CCl₄ at room temperature to form [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η⁵]tricarbonylmanganese (2a), whose X-ray crystal structure is reported to complement that of its isomer [6-oxo-2,4,7-triphenylcyclohepta-1,4-dienyl-1,2,3,4,5-η]tricarbonylmanganese (3a), previously obtained from the reaction under reflux; but for 1a and PhCCPh the pyranyl complex cannot be isolated before rearrangement to the 3a analogue occurs. More forcing reaction conditions for 1a with Me₃SiCCH and for [1-(2-trifluoromethylphenyl)-2-[(E)-3-(2-trifluoromethylphenyl)prop-2-en-1-oyl-κO]ethenyl-κC¹]tetracarbonylmanganese (1b) with Me₃SiCCH and PhCCH give new analogues of 3a where previously only 2a analogues had been isolated.The reaction in CCl₄ under reflux of PhCCH and the β-deuterio analogue of 1a, [1-phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-3d-κO]ethenyl-κC¹]tetracarbonylmanganese, gave deuteriated 3a with exo-D at the α-carbon, C7. This is inconsistent with the Mn-mediated Ph migration mechanism originally proposed to accommodate the endo position of Ph in 3a, and instead it implicates a cyclopropyl carbonyl-addition intermediate or a cyclopropyl acyl-substitution transition state in the key rearrangement step for 2a → 3a.     

仓库害虫集合信息素的合成锈赤扁谷盗和长角扁谷盗

本文报道通过不保护羟基的10-癸炔醇-1, 在LiNH2作用下直接与W-溴代羧酸酯反应引入羟酸基团, 从而缩补了反应步骤并提高了收率。十一碳烯内酯和十三碳烯内酯的心率为14.4%和11%, 立体选择性Z>98%。     

Microwave-enhanced Pd(0)/acetic acid catalyzed allylation reactions of C, N, and O-pronucleophiles with alkynes

An efficient method for the allylation of C, N, and O-nucleophiles with alkynes under solvent-free conditions and by microwave activation is established. The process can be termed as a real eco-chemical process since no waste elements are produced in the reaction, moreover it is solvent free. This technique can also be used for the allylation of dimethyl methylmalonate, which proves inert under the previously reported reaction conditions (refluxing in 1,4-dioxane).     

Three-component coupling of aldehyde, alkyne, and amine catalyzed by silver in ionic liquid

A three-component coupling of aldehyde, alkyne, and amine was developed by using gold, copper, or silver as catalysts in ionic liquid.     

3,3′-Functionalized octahydro-BINOL: a facile synthesis and its high enantioselectivity in the alkyne addition to aldehydes

A facile synthesis of an enantiomerically pure 3,3′-bismorpholinylmethyl H₈-BINOL ligand has been developed. This compound in combination with Et₂Zn and Ti(OⁱPr)₄ is found to catalyze the highly enantioselective reaction of phenylacetylene with aromatic aldehydes. The enantioselectivity of this catalytic process for the reactions of ortho-substituted benzaldehydes is significantly higher than that based on H₈-BINOL.     

Pictet Spengler-type reactions in 3-arylmethylpiperazine-2,5-diones. Synthesis of pyrazinotetrahydroisoquinolines

The behavior of aldehydes and acetals as N-alkylating agents of 1-acetyl-3-arylmethylpiperazine-2,5-diones and the subsequent cyclization of the N-alkylated products was studied. Use of paraformaldehyde in different reaction conditions gave 6-unsubstituted 3,6,11,11a-tetrahydro-2H-pyrazino[1,2-b]isoquinoline-1,4-diones and, in some cases, benzo[f]pyrazino[1,2-c]1,3-oxazepine-1,4-diones. Succesful reactions with benzaldehyde required a first activation of the lactam function and a catalyzed N-alkylation with the aldehyde dimethyl acetal. The isolated O,N-amidoacetals thus obtained were submitted to a diastereoselective Pictet Spengler-type reaction that worked with arenes at several degrees of ring activation and with thiophene to give 6-phenylpyrazinoisoquinolinediones and the corresponding thieno analog.     

The alkyne-anion promoted ring-contraction of hexachlorotropone: synthesis and structure of [trimethylsilyl(pentachlorobenzoyl)ethyne]-hexacarbonyldicobalt

The reaction of hexachlorotropone with trimethylsilylethynyl-lithium leads to contraction of the seven-membered ring via a semibenzilic acid rearrangement to yield pentachlorophenyl trimethylsilylethynyl ketone, 4. Treatment of 4 with dicobalt octacarbonyl yields the corresponding alkyne-dicobalt hexacarbonyl, 6, which has been characterized by X-ray crystallography.