932370-72-4Relevant academic research and scientific papers
Synthesis of Highly Substituted Pyridines via [4 + 2] Cycloadditions of Vinylallenes and Sulfonyl Cyanides
Bartko, Samuel G.,Hamzik, Phillip J.,Espindola, Leandro,Gomez, Christian,Danheiser, Rick L.
, p. 548 - 563 (2019/12/27)
A convergent strategy for the synthesis of multisubstituted pyridines is described. Vinylallenes combine with commercially available arylsulfonyl cyanides in Diels-Alder cycloadditions to generate isopyridine cycloadducts that are converted to pyridines upon further heating or addition of a base. The 2-sulfonylpyridine products undergo nucleophilic aromatic substitution reactions with oxygen and carbon nucleophiles to provide access to a variety of highly substituted pyridines.
Copper(I)-catalyzed regio- and stereoselective intramolecular alkylboration of propargyl ethers and amines
Iwamoto, Hiroaki,Ozawa, Yu,Kubota, Koji,Ito, Hajime
, p. 10563 - 10573 (2018/05/31)
The copper(I)-catalyzed regio- and stereoselective intramolecular alkylation of propargyl ethers and amines bearing an alkyl electrophilic moiety has been developed. The reaction showed high functional group tolerance and gave highly functionalized alkenylboronates bearing heterocyclic rings, which are versatile synthetic intermediates in organic chemistry. The borylation products can be transformed into multisubstituted alkenes through stereospecific transformations. Mechanistic studies showed that the chemo- and stereoselectivity of copper(I)-catalyzed borylation depends on the type of leaving group. Density functional theory calculations suggested that the regioselectivity of the borylcupration of the alkyne is controlled by the electronic effect of the oxygen atom of the propargyl ether in combination with the steric congestion between the boryl group and the substituent at the propargylic position.
Preparation of substituted cyclopentadienes through platinum(II)-catalyzed cyclization of 1,2,4-trienes
Funami, Hideaki,Kusama, Hiroyuki,Iwasawa, Nobuharu
, p. 909 - 911 (2007/10/03)
(Chemical Equation Presented) A pinch of platinum... Platinum(II)-catalyzed cyclization of 1,2,4-trienes proceeds under mild conditions to give well-defined, highly substituted cyclopentadienes in good yield. The reaction was confirmed to proceed through
Synthesis of trisubstituted furans from epoxypropargyl esters by sequential SmI2-promoted reduction - Elimination and Pd(II)-catalyzed cycloisomerization
Aurrecoechea,Perez,Solay
, p. 564 - 569 (2007/10/03)
A two-step one-pot synthesis of 2,3,5-trisubstituted furans 8 from 4,5-epoxyalk-2-ynyl esters 6 is described. The sequence is initiated by a SmI2-promoted reduction that takes advantage of the ability of the alkynyloxirane moiety present in 6 to accept electrons from SmI2. The resulting organosamarium species then eliminates an adjacent acetate or benzoate leaving group, leading to the formation of unstable 2,3,4-trien-1-ols 7. Without isolation, these are cycloisomerized to furans 8 by treatment with a catalytic amount of a Pd(II) complex and a proton source. The whole sequence takes place under mild reaction conditions. Some useful functional groups such as cyano and α, βunsaturated esters are tolerated, but benzyl- and silyl-protected hydroxyl groups are deprotected to some extent. Starting materials can be easily assembled using reliable reactions from acetylene, an aldehyde or ketone, and a vinyl halide fragment. This offers the possibility of introducing branched substituents at C-5 of the furan ring.
