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A copper(II)-catalyzed protocol to construct trans-configured β-lactams and spirocyclic β-lactams from oximes and methyl propiolate has been developed, which features excellent substrate flexibility and diastereoselectivity (up to >99:1 dr). In situ FT-IR mechanistic experiments support that ketene species might be involved in the formation of β-lactams.

The highly efficient α- and vicinal bis-addition of cyclic imides to methyl propiolate in high yields and β-addition of these imides to α-imidoacrylates in quantitative yields is reported. These reactions offer a simple metal-free method for a gram-scale preparation of practically useful α-imidoacrylates and vicinal bisimides under mild conditions with high atom economy and selectivity.

A new and metal-free approach to the synthesis of substituted 6H-benzo[c]chromenes has been developed. This three-step synthetic sequence starts from variously substituted salicylaldehydes and α,β-unsaturated carbonyl compounds to form the chromene core. The de novo ring-forming key step is based on a highly regioselective intermolecular Diels–Alder cycloaddition between 3-vinyl-2H-chromenes and methyl propiolate, followed by oxidative aromatization of the cyclohexadiene cycloadduct intermediate to obtain the final products in good yields (up to 94% over two steps). A modular and divergent design was followed, including a multicomponent reaction, to maximize the scaffold diversity obtained from our approach. The mechanism, investigated by DFT calculations, was confirmed to be concerted through a slightly asynchronous transition state. Energetic analysis of the transition states which have been found confirmed the experimental results in terms of regioselectivity and reactivity tendencies.

The present study reports on the powerful nematicidal activity of a series of electron-deficient alkynes against the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood. Interestingly, we found that the conjugation of electron-withdrawing carbonyl groups to an alkyne triple bond was extremely proficient in inducing nematode paralysis and death. In particular, dimethylacetylenedicarboxylate (10), 3-butyn-2-one (1), and methyl propiolate (4), with EC50/48 h of 1.54 ± 0.16, 2.38 ± 0.31, and 2.83 ± 0.28 mg/L, respectively, were shown to be the best tested compounds. Earlier studies reported on the ability of alkynoic esters and alkynones to induce a chemoselective cysteine modification of unprotected peptides. Thus, also following our previous findings on the impairment of vacuolar-type proton translocating ATPase functionality by activated carbonyl derivatives, we speculate that the formation of a vinyl sulfide linkage might be responsible for the nematicidal activity of the presented electron-deficient alkynes.

International audience; The first example of a silyl gold(I) complex stabilized by an N-heterocyclic carbene (NHC) was synthesised and fully characterized, including crystallographically. The syn insertion of methyl propiolate into the Au-Si bond leading to a vinyl gold complex is reported. As substantiated by X-ray diffraction analysis, the reaction proceeds with opposite regioselectivity compared to that observed previously with phosphine silyl gold(I) complexes.

Reactions of penta-2,4-dienethioamides with acetylenedicarboxylic acid, methyl and ethyl esters, and methyl propiolate were systematically studied, and a number of new 2,3-dihydro-5H-thiazolo[3,2-a...

Methyl propiolate (HC CCOOCH3, MP) isolated in argon and nitrogen matrices was experimentally studied by infrared spectroscopy and by quantum chemical calculations. The calculations, carried out at the DFT(B3LYP) and MP2 levels of theory, predict the existence of two conformers with a planar skeleton. In situ broadband UV light (λ > 200 nm) irradiation of matrix-isolated MP led to the production of new bands ascribed to conformer II testifying the occurrence of the I →II photoisomerization. No other photochemical processes were observed. Assignment of the IR spectra of both conformers is presented, considerably extending the vibrational information available for this molecule hitherto.

A new organometallic iodide cluster complex (Bu4N)2[W6I8(C≡C–C(O)OCH3)6] (I), analogous to the previously described (Bu4N)2[Mo6I8(C≡C–C(O)OCH3)6], was obtained by the reaction of (Bu4N)2[W6I14] with silver methyl propiolate AgC≡C–C(O)OCH3. The crystal structure was established for the tetraphenylphosphonium salt (Ph4P)2[W6I8(C≡C–C(O)OCH3)6] (II). According to X-ray diffraction (CIF file CCDC no. 1829205), tungsten atoms in II are coordinated by terminal carbon atoms of methyl propiolate ligands at W–C distances of 2.220(12)–2.268(14) A. The methyl propiolate complexes were characterized by electrospray mass spectrometry, 1H and 13C NMR spectroscopy, elemental analysis, and IR spectroscopy.

Novel polysubstituted pyrrolo[1′,2′:1,2]azocino[4,5-c]quinolines were efficiently synthesized by a one-pot three-component reaction of proline, isatins and chalcones in refluxing methanol and by a sequential domino annulation reaction with methyl propiolate in refluxing acetonitrile. The reaction with isatins without an N-protecting group afforded hexahydropyrrolo[1′,2′:1,2]azocino[4,5-c]quinolines, while the reaction with N-benzylisatins gave octahydropyrrolo[1′,2′:1,2]azocino[4,5-c]quinolones with an additional propiolate unit connecting to a dihydropyridyl ring. The reaction mechanism with domino [3 + 2]cycloaddition, ring-expansion and annulation processes was rationally proposed for the formation of polycyclic products.

Ferrocenyl methyl ketone reacts with aromatic aldehydes yielding 1-ferrocenyl-3-aryl-propenones (chalcones), which upon treatment with Lawesson’s reagent (LR) are converted to the corresponding thiochalcones. The latter enter the thia-Diels–Alder reaction with acetylenic dienophiles (DMAD and methyl propiolate) to give ferrocenyl-substituted 4H-thiopyrans. In the case of methyl propiolate, the formation of the six-membered ring occurs with complete regioselectivity.

A simple approach to a series of 2,4a,7,7a-tetrahydro-1H-cyclopenta[c]pyridines was proposed on the basis of the amino-Claisen rearrangement of readily accessible 2-azabicyclo[2.2.1]hept-5-enes under the action of dialkyl acetylenedicarboxylates, methyl propiolate or propiolamide. The rearrangement is highly diastereoselective and leads to the formation of only one isomer with cis-annulation of the five- and six-membered rings in satisfactory yields. Using the developed method, close analogs of the altemicidin and SB-203207 cores were synthesized.

With 2-(trimethylsilyl)aryl triflates as aryne precursors, an unprecedented three-component carboarylation reaction of unactivated imines with arynes and carbon nucleophiles has been developed to access a variety of functionalized tertiary amines under transition metal-free conditions. Suitable carbon nucleophiles include chloroform, acetonitrile, and methyl propiolate.

A short route toward aromatic cassane diterpenes from labdane terpenoids has been developed. In the key step, the aromatic ring with the oxygenated function at C-12 and the characteristic carbon group at C-14 of the target compounds is elaborated via a Diels-Alder/aromatization sequence of a furanosesquiterpene and methyl propiolate. On this basis, the synthesis of the proposed structure of benthaminin 1 from trans-communic acid has been achieved. The physical properties of the synthetic compound are somewhat different from those reported for the natural product.

The excellent catalytic effect on methyl propiolate addition to a wide range of aromatic and aliphatic aldehydes promoted by inexpensive and commercially available BINOL-based ligand is reported. The catalyst systems showed high yields and excellent enantioselectivities for aromatic aldehydes, and excellent yields and high enantioselectivities for aliphatic aldehydes.

Compounds with propargylamine moiety are useful synthetic precursors of several important classes of nitrogen-containing heterocycles. The title compound, methyl (2E)-3-[3-benzyl-2-(3-methoxy-3-oxoprop-1-yn-1-yl)-2-(1-naphthyl)imidazolidine-1-yl]acrylate, has been prepared by domino-reaction, employing easily available 1-benzyl-2-(1-naphthyl)-4,5-dihydro-1H-imidazole and methyl propiolate in a high 92% yield. The structure of title compound was determined using 1H-NMR, 13C-NMR, UV, FT-IR and HRMS (High-Resolution Mass Spectrometry).

[Formula: see text]-Enaminoesters were generated in situ by the reaction of aliphatic or aromatic primary amines to electron-deficient alkynes, dimethyl acetylenedicarboxylate, and methyl propiolate. [Formula: see text]-Enaminoesters thus formed were reacted with 1-adamantanamine and formaldehyde in methanol to give novel molecular hybrids: dimethyl 3-((3s,5s,7s)-adamantan-1-yl)-1-(alkyl/aralkyl/aryl)-1,2,3,4-tetrahydropyrimidine-5,6-dicarboxylates (5a-j) and methyl 3-((3s,5s,7s)-adamantan-1-yl)-1-(alkyl/aralkyl/aryl)-1,2,3,4-tetrahydropyrimidine-5-carboxylates (9a-j). The structures of the molecular hybrids have been established based on the spectral and analytical data. Structural confirmation of the products was done by X-ray crystallography of 5d as a representative product of the series.

A powerful, novel approach to meroterpenes conicol, epiconicol and didehydroconicol has been achieved via a key step Diels–Alder reaction of ( E )-3-methyl-1-(2′,5′-dimethoxyphenyl)buta-1,3-diene as diene with methyl vinyl ketone, methyl acrylate or methyl propiolate as dienophiles. Activation by high pressure (9 kbar) or by the use of Lewis acid catalysts, allows the Diels–Alder reaction to proceed in excellent yield and diastereoselectively to form cyclohexenyl-benzene cycloadducts, which are useful precursors for conicols. The successful total syntheses of conicol, epiconicol and didehydroconicol, are described.

Three stereoselective synthetic approaches to tetrahydrofuran-containing biaryl scaffolds are described. All approaches involve a high-pressure promoted Diels-Alder reaction of substituted diene with methyl propiolate to give, after aromatization, the corresponding biaryl. The tetrahydrofuran moiety can be created starting from aryl-Br or aryl-CO2Me functional groups through a γ-phenylseleno ketone intermediate.

Nitrilimine cycloadditions to ethylenes, acetylenes, and activated nitriles have been exploited in the presence of catalytic amounts of oleic-acid-coated iron oxide nanoparticles (diameter = 11.9 +/- 1.0 nm). The reactions were fully regioselective with monosubstituted ethylenes and ethyl cyanoformiate, while mixtures of cycloadducts were obtained in the presence of methyl propiolate. The intervention of iron oxide nanoparticles allowed carrying out the cycloadditions at milder conditions compared to the metal-free thermal processes. A labile intermediate has been proposed to explain this behavior.

The three-component reactions of α,β-unsaturated N-arylaldimines, dimethyl acetylenedicarboxylate (methyl propiolate) and isatylidene malononitriles in dry acetonitrile at room temperature afforded polysubstituted spiro[indoline-3,4′-pyridines] in good yields and with high diastereoselectivity. Under similar reaction conditions, the corresponding functionalized spiro[indene-2,4′-pyridines] were also obtained from the three-component reactions containing 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)malononitrile.

Hetaryl-substituted thiochalcones react with acetylenic mono- and diesters in the THF solution in the presence of LiClO4 at 65°C to give, after 24 h, 4H-thiopyran carboxylates and dicarboxylates, respectively, in moderate to good yields. The same reactions were performed also in the THF solution without a catalyst under microwave irradiation. In that case, the reaction time was reduced to three minutes and, in most cases, an improvement in the yield of the [4+2]-cycloadduct was observed. The reactions with methyl propiolate occurred regioselectively and the 3-carboxylates were formed exclusively.

The excellent catalytic effect on methyl propiolate addition to a wide range of aromatic and aliphatic aldehydes promoted by inexpensive and commercially available BINOL-based ligand is reported. The catalyst systems showed high yields and excellent enantioselectivities for aromatic aldehydes, and excellent yields and high enantioselectivities for aliphatic aldehydes.

The three-component reactions of α,β-unsaturated N-arylaldimines, dimethyl acetylenedicarboxylate (methyl propiolate) and isatylidene malononitriles in dry acetonitrile at room temperature afforded polysubstituted spiro[indoline-3,4′-pyridines] in good yields and with high diastereoselectivity. Under similar reaction conditions, the corresponding functionalized spiro[indene-2,4′-pyridines] were also obtained from the three-component reactions containing 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)malononitrile.

A novel compound, methyl 3-(quinolin-2-yl)indolizine-1-carboxylate (2) has been synthesized by cycloaddition reaction of 1-(quinolin-2-ylmethyl)pyridinium ylide (1) with methyl propiolate in presence of sodium hydride in THF. The structure of this compound was established by IR, 1H-NMR, 13C-NMR and MS data

2-(Chloromethyl)-5,6,7,8-tetrahydropyrido[4',3':4,5]thieno[2,3-d]pyrimidin-4(3Н)-ones reacted with acetylenedicarboxylate ester, methyl propiolate or acetylacetylene, forming mixtures of 2-(chloromethyl)-5,6,7,10-tetrahydropyrimido[5',4':4,5]thieno[3,2-d]azocin-4(3Н)-ones and 2'-chloromethyl-6'-methylidene-2,3-dihydro-1Н-spiro[pyrido[4,5']thieno[2,3-d]pyrimidin]-4'(3'H)-ones in various ratios. Analogous products were also obtained in the reaction of 2-(methoxymethyl) derivative with methyl propiolate, while using 2-[(morpholin-4-yl)-methyl] derivative in a similar reaction led to the formation of a more complex product mixture.

Multisubstituted dihydropyridines (III) are efficiently obtained from methyl propiolate (II) and propargylamines (I) with high regioselectivity.