6746-94-7Relevant articles and documents
Evidence for Concert in the Thermal Unimolecular Vinylcyclopropane to Cyclopentene Sigmatropic 1,3-Shift
Gajewski, Joseph J.,Olson, Leif P.,Willcott, M. Robert
, p. 299 - 306 (1996)
Gas phase pyrolysis of cis-2,3-dideuterio-trans-(1'-tert-butyl-2'-(Z)-deuteriovinyl)cyclopropane at 290 deg C gives trans,trans-3,4,5-trideuterio-1-tert-butylcyclopentene as the major 1,3-shift product with greater than 90percent stereospecificity in an orbital symmetry "allowed" suprafacial-inversion sense after correction for the geometric isomerization of starting material and the other materials present.The isotopic substitution at the critical sites of rearrangement eliminates steric of electronic influences of substitutents on a biradical pathway as a source of the suprafacial- inversion stereochemistry observed with more highly substituted drivatives.The stereochemical results coupled with a normal deuterium kinetic isotope effect (kH/2kD=1.14 at 311.6 deg C) at the exo-methylene carbon are best interpreted in terms of a concerted pathway for rearrangement.A less likely alternative is a stereospecific disrotatory ring opening to a biradical followed by rate-determining closure to a five-membered ring.Accompanying the rearrangement is geometric isomerization of starting material resulting from C-1-C-2 bond fission which favors either the single methylene rotation or a double rotation by a factor of 10 over single rotation at the vinyl-bearing carbon.
Safe and environment-friendly preparation method of cyclopropyl acetylene
-
Paragraph 0037-0070, (2020/08/22)
The invention relates to the field of medicine synthesis, and discloses a safe and environment-friendly preparation method of cyclopropylacetylene, which comprises the following steps: 1) performing chlorination reaction; 2) carrying out an ethynylation reaction; and 3) synthesizing cyclopropyl methyl ketone from the by-product E/Z-2, 5-dichloro-2-pentene. The process provided by the invention ishigh in chlorination yield; the chlorination reagent is triphosgene, the reaction condition is mild, and the safety is high. An organic solvent, inorganic base and a phase transfer catalyst system areadopted in the ethynylation reaction, and the yield is high; the high-flash-point organic solvent dilutes the reaction system, and the reaction is safe. E/Z-2-5-dichloro-2-pentene generated through the chlorination reaction is subjected to sulfuric acid dechlorination and cyclization and then converted into cyclopropyl methyl ketone, and application is achieved. Potassium chloride is treated as aby-product, and an organic solvent, water, organic alkali and a catalyst are used in chlorination reaction; an organic solvent and a phase transfer catalyst used in the ethynylation reaction can be recycled. The reaction is environment-friendly, only two potassium salt byproducts of potassium chloride and potassium sulfate are formed, and zero emission is basically realized.
Palladium-Catalyzed Cascade Intramolecular Cyclization and Allylation of Enynoates with Allylic Alcohols
Qiu, Sheng-Qi,Ahmad, Tanveer,Xu, Yun-He,Loh, Teck-Peng
, p. 6729 - 6736 (2019/06/14)
A Pd(II)-catalyzed mild and highly regioselective 6-endo cyclization/allylation reaction of enynoates with simple allylic alcohols has been developed. Under mild reaction conditions, the vinyl palladium species generated in situ after cyclization could insert C-C double bond of allylic alcohol through cross-coupling reaction and lead to the formation of allyl pyrone via β-OH elimination. This cascade cross-coupling reaction represents a direct and atom economic methodology for the construction of novel allyl pyrones in moderate to good yields.
Controlled photorelease of alkynoic acids and their decarboxylative deprotection for copper-catalyzed azide/alkyne cycloaddition
Vohradská, Nikoleta,Sánchez-Carnerero, Esther M.,Pastierik, Tomá?,Mazal, Ctibor,Klán, Petr
supporting information, p. 5558 - 5561 (2018/06/04)
A controlled photorelease of alkynoic acids from the meso-methyl BODIPY photoremovable protecting group facilitates their subsequent efficient decarboxylation to give terminal alkynes for a CuI-catalyzed azide/alkyne cycloaddition. The quantum efficiencies of the photochemical step and the kinetics of the click reaction step are reported.
