927-80-0Relevant articles and documents
Structural, spectroscopic, and photochemical study of ethyl propiolate isolated in cryogenic argon and nitrogen matrices
Fausto, Rui,Lopes, S.,Nikitin, T.
, (2020/07/15)
Ethyl propiolate (HC ≡ CCOOCH2CH3, EP) was studied experimentally by infrared spectroscopy in argon and nitrogen cryomatrices (15 K) and by quantum chemical calculations (at the DFT(B3LYP) and MP2 levels of theory). Calculations predict the existence of four conformers: two low-energy conformers (I and II) possessing the carboxylic moiety in the cis configuration (O=C–O–C dihedral equal to ~0°) and two higher-energy trans forms (O=C–O–C dihedral equal to ~180°; III and IV). The conformation of the ethyl ester group within each pair of conformers is either anti (C–O–C–C equal to 180°; in conformers I and III) or gauche (C–O–C–C equal to ±86.6° in II, and ± 92.5° in IV). The two low-energy cis conformers (I and II) were predicted to differ in energy by less than 2.5 kJ mol?1 and were shown to be present in the studied cryogenic matrices. Characteristic bands for each one of these conformers were identified in the infrared spectra of the matrix-isolated compound and assigned taking into account the results of normal coordinate analysis, which used the geometries and harmonic force constants obtained in the DFT calculations. The two trans conformers (III and IV) were estimated to be 17.5 kJ mol?1 higher in energy than the conformational ground state (form I) and were not observed experimentally. The unimolecular photochemistry of matrix-isolated EP (in N2 matrix) was also investigated. In situ irradiation with UV light (λ > 235 nm) leads mainly to decarbonylation of the compound, with generation of ethoxyethyne, which in a subsequent photoreaction generates ketene (plus ethene).
Combined epimerisation and acylation: Meerwein-ponndorf-verley-oppenauer catalysts in action
Klomp, Dirk,Djanashvili, Kristina,Svennum, Nina Cianfanelli,Chantapariyavat, Nuttanun,Wong, Chung-Sing,Vilela, Filipe,Maschmeyer, Thomas,Peters, Joop A.,Hanefeld, Ulf
, p. 483 - 489 (2007/10/03)
A practical racemisation-epimerisation method for chiral secondary alcohols has been developed. Meerwein-Ponndorf-Verley-Oppenauer catalysts such as neodymium(III) isopropoxide are able to racemise these alcohols with retention of other stereocentres in the molecule. This is particularly useful for the recycling of the undesired products of kinetic resolutions of alcohols. By combination of such a racemisation with an acylation using isopropenyl or ethoxyvinyl esters as acyl donors, a fast straightforward recycling of starting materials may be achieved. The combined epimerisation and acylation process is demonstrated for the steroid estradiol methyl ether.
The behaviors of metal acetylides with dinitrogen tetroxide
Woltermann, Christopher J.,Shechter, Harold
, p. 354 - 369 (2007/10/03)
Lithium phenylacetylide (1a) and N2O4 (2) at - 78° yield diphenylbutadiyne (6a) by oxidative coupling, phenylacetylene (7a) by oxidation and then solvent H-abstraction, and benzoyl cyanide (8) by dimerizative-rearrangement of nitroso(phenyl)acetylene (23). Nitro(phenyl)acetylene (3, R = Ph) is not obtained. Benzonitrile (9), a further product, possibly results from hydrolytic decomposition of nitroso(phenyl)ketene (27) generated from phenylacetylenyl nitrite (26). Phenylacetylene (7a) and 2 give, along with (E)- and (Z)-1,2-dinitrostyrenes (34 and 35, resp.), 3-benzoyl-5-phenylisoxazole (10), presumably as formed by cycloaddition of benzoyl nitrile oxide (40) to 7a. Further, 2 reacts with other lithium acetylides (1b-1e), and with sodium, magnesium, zinc, copper, and copper lithium phenylacetylides, 1f-1l, to yield diacetylenes 6a-6c and monoacetylenes 7a-7c. Conversions of metallo acetylide aggregates to diacetylenes are proposed to involve generation and addition reactions of metallo acetylide radical cationic intermediates in cage, further oxidation, and total loss of metal ion. Loss of metal ions from metallo acetylide radical cations and H-abstraction by non-caged acetylenyl radicals will give terminal acetylenes. The principal reactions (75-100%) of heavy metal acetylides phenyl(trimethylstannyl)acetylene (44) and bis(phenylacetylenyl)mercury (47) with 2 are directed nitrosative additions (NO+) and loss of metal ions to give nitroso(phenyl)ketene (27), which converts to benzoyl cyanide (8).
A high yielding, reproducible synthesis of trimethylsilylketene
Black, T. Howard,Farrell, John R.,Probst, Donald A.,Zotz, Michael C.
, p. 2083 - 2088 (2007/10/03)
A two-step sequence for the preparation of trimethylsilylketene, from chloroacetaldehyde diethyl acetal via ethoxyacetylene, has been modified and optimized.
Synthesis and phosphorylation of 1-ethoxy-1-trimethylsiloxy-2-trimethylsilylthioethene
Burilov, A. R.,Cherepashkin, D. V.,Pudovik, M. A.
, p. 20 - 21 (2007/10/03)
A new organosilicon reagent, 1-ethoxy-1-trimethylsiloxy-2-trimethylsilylthioethene, was prepared by silylation of ethyl (trimethylsilylthio)acetate. its thermal isomerization and phosphorylation with bis(diethylamino)chlorophosphine and diphenylchlorophosphine were studied.
Dehydrobromination of 1,2-Dibromoethoxyethane Using Various Amine Bases
Stalick, Wayne M.,Khorrami, Ali,Hatton, Kimi S.
, p. 3577 - 3581 (2007/10/02)
1,2-Dibromoethoxyethane was treated with a number of basic reagents, mainly tertiary amines, to accomplish dehydrobromination to 1-bromo-2-ethoxyethene, a precursor to an acetaldehyde carbanion equivalent.The yield of this vinyl bromide and the other common byproducts of reaction varied markedly depending on the base and reaction conditions employed.Direct distillation of the product under reduced pressure from a tertiary amine solution was the method of choice, showing little if any effect of temperature and giving reproducible results.Following this procedure, N,N-dimethyldodecylamine was the preffered base for this reaction.This paper presents results of the dehydrobromination reaction using more than 30 different bases and conditions
Ru-CATALYZED OXIDATION OF SUBSTITUTED ACETYLENES TO α-KETO ESTERS AND α-KETO AMIDES WITH IODOSYLBENZENE
Mueller, Paul,Godoy, Jose
, p. 3661 - 3664 (2007/10/02)
Oxidation of alkynyl ethers and -amines with iodosylbenzene in presence of Ru-catalysts affords α-keto esters and α-keto amides in 44-84percent yield.These conversions can also be effected with RuO4.
A CONVENIENT ROUTE TO ALKYNES VIA PHASE TRANSFER CATALYSIS; ( APPLICATIONS OF PHASE TRANSFER CATALYSIS, PART 19 )
Dehmlow, Eckehard V.,Lissel, Manfred
, p. 1653 - 1658 (2007/10/02)
High yield, rapid formations of alkynes from vic-dibromides are possible using powered potassium hydroxide and catalytic amounts of lipophilic phase transfer catalysts.Reasons are given why molar amounts of expensive catalysts were necessary in earlier procedures.
A FACILE SYNTHESIS OF METHYL (+/-)-10,11-EPOXY-3,7,11-TRIMETHYLDODECA-2,6-DIENOATE, THE INSECT JUVENILE HORMONE III
Biernacki, Wladyslaw
, p. 777 - 780 (2007/10/02)
A rapid synthesis of the title compound has been described.
