Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition
作者:Hao Yuan、Jianxian Gong、Zhen Yang
DOI:10.1021/acs.orglett.6b02703
日期:2016.11.4
A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]heptenes has been developed, featuring a tandemreaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloadditionreaction. This tandemreaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic
Chiral Copper(II) Phosphate Catalyzed Enantioselective Synthesis of Isochromene Derivatives by Sequential Intramolecular Cyclization and Asymmetric Transfer Hydrogenation of<i>o</i>-Alkynylacetophenones
作者:Kodai Saito、Yuki Kajiwara、Takahiko Akiyama
DOI:10.1002/anie.201308303
日期:2013.12.9
A good mix: The title reaction of o‐alkynylacetophenones with the Hantzsch ester in the presence of a chiral copper/phosphate catalyst proceeds in good yields with excellent enantioselectivities. The key intermediate for enantiocontrol is the ion pair of the carbonyl ylide with a chiral phosphate anion, and this process provides straight forward access to highly enantioriched chiral isochromenes.
Ruthenium-Catalyzed Aromatization of Aromatic Enynes via the 1,2-Migration of Halo and Aryl Groups: A New Process Involving Electrocyclization and Skeletal Rearrangement
作者:Hung-Chin Shen、Sitaram Pal、Jian-Jou Lian、Rai-Shung Liu
DOI:10.1021/ja0379159
日期:2003.12.1
The halo and aryl substituents of the 1,2-disubstituted styryl group of aromatic enynes undergo a 1,2-shift in the aromatization reaction catalyzed by TpRuPPh3(CH3CN)2PF6 (10 mol %) in toluene (110 degrees C, 6-8 h). The aryl group shifts to the neighboring olefin carbon, and the iodo (or bromo) substituent migrates to the terminal alkyne carbon. The mechanisms of these two migrations have been elucidated
excellent yields. The salient features of this reaction include readily available starting materials, good functional group compatibility, mild reaction conditions, no column chromatography, high bond-formation efficiency, and ease in further transformations. Notably, this is the first example for the synthesis of 2H-indazoles with in situ generated diazoniumsalt as the nitrogen source, and a mechanistic
Substituent Effect on the Reactions of OsCl<sub>2</sub>(PPh<sub>3</sub>)<sub>3</sub> with <i>o</i>-Ethynylphenyl Carbonyl Compounds
作者:Wenqing Ruan、Tilong Yang、Chuan Shi、Wei Bai、Herman H. Y. Sung、Ian D. Williams、Zhenyang Lin、Guochen Jia
DOI:10.1021/acs.organomet.9b00810
日期:2020.2.24
Reactions of OsCl2(PPh3)3 with o-ethynylphenyl-carbonyl compounds o-HC≡CC6H4C(O)R (2, R = H (a) and Et (b)) produced the η3-o-ethynylphenyl-carbonyl complexes OsCl2(PPh3)2η3-(o-HC≡CC6H4C(O)R)} (3). Treatment of OsCl2(PPh3)3 with o-HC≡CC6H4C(O)NEt2 (2c) produced the complex OsCl2(PPh3)2═C═CH-o-C6H4C(O)NEt2)(CH═CC6H4–C(O)NEt2)} (4c), which contains both a vinylidene and a vinyl or isobenzofuranyl carbene