2288-18-8Relevant articles and documents
Yu, Fei-Le,Bai, Da-Chang,Liu, Xiu-Yan,Jiang, Yang-Jie,Ding, Chang-Hua,Hou, Xue-Long
, p. 3317 - 3321 (2018)
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Grummit,Leaver
, p. 1595 (1952)
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Efficient Synthesis of 3,6-Dihydro-2H-pyrans via [3+2+1] Annulation Based on the Heteroatom-free Tri-atom Donor
Li, Hui,Liu, Haiping,Liu, Yufeng,Cao, Zhongzhong,Su, Miaodong,Fu, Meiqiang,Luo, Weiping,Liu, Qiang,Guo, Cancheng
, p. 5392 - 5399 (2019/11/11)
A new [3+2+1] annulation strategy based on the heteroatom-free tri-atom donor to synthesize 3,6-dihydro-2H-pyrans has been developed. In this method, 2-arylpropylene served as tri-atom donor to contribute three carbon atoms, the heteroatom was provided by aldehyde, and DMSO served as one carbon donor and solvent. This annulation reaction gave 3,6-dihydro-2H-pyrans in moderate to good yields. Based on the control experiments, a possible mechanism was proposed. (Figure presented.).
Regio- and Diastereoselective Iron-Catalyzed [4+4]-Cycloaddition of 1,3-Dienes
Kennedy, C. Rose,Zhong, Hongyu,MacAulay, Rachel L.,Chirik, Paul J.
supporting information, p. 8557 - 8573 (2019/06/04)
A family of single-component iron precatalysts for the [4+4]-cyclodimerization and intermolecular cross-[4+4]-cycloaddition of monosubstituted 1,3-dienes is described. Cyclooctadiene products were obtained with high regioselectivity, and catalyst-controlled access to either cis- or trans-diastereomers was achieved using 4-substituted diene substrates. Reactions conducted either with single-component precatalysts or with iron dihalide complexes activated in situ proved compatible with common organic functional groups and were applied on multigram scale (up to >100 g). Catalytically relevant, S = 1 iron complexes bearing 2-(imino)pyridine ligands, (RPI)FeL2 (RPI = [2-(2,6-R2-C6H3-Na-CMe)-C5H4N] where R = iPr or Me, L2 = bis-olefin), were characterized by single-crystal X-ray diffraction, M??bauer spectroscopy, magnetic measurements, and DFT calculations. The structural and spectroscopic parameters are consistent with an electronic structure description comprised of a high spin iron(I) center (SFe = 3/2) engaged in antiferromagnetically coupling with a ligand radical anion (SPI = -1/2). Mechanistic studies conducted with these single-component precatalysts, including kinetic analyses, 12C/13C isotope effect measurements, and in situ M??bauer spectroscopy, support a mechanism involving oxidative cyclization of two dienes that determines regio- and diastereoselectivity. Topographic steric maps derived from crystallographic data provided insights into the basis for the catalyst control through stereoselective oxidative cyclization and subsequent, stereospecific allyl-isomerization and C-C bond-forming reductive elimination.
