Uma, M.; Gopalakrishnan, M.; Jayabharathi, J., Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 1995, vol. 34, # 7, p. 612 - 616
Catalytic Asymmetric 1,3‐Dipolar Cycloaddition of β‐Fluoroalkylated α,β‐Unsaturated 2‐Pyridylsulfones with Nitrones for Chiral Fluoroalkylated Isoxazolidines and γ‐Amino Alcohols
across various aromatic and aliphatic nitrones in the presence of a chiral NiII/bis(oxazoline) catalyst. The process was tuned by 4 Å molecular sieves, chiralbis(oxazoline) ligands, reaction solvents, and temperature. A wide array of optically pure fluoroalkylated isoxazolidines were obtained, thus facilitating the asymmetric synthesis of an enantioenriched α‐trifluoromethylated γ‐amino alcohol in gram‐scale
An enantioselective Mannich‐type reaction of 3‐butynol and nitrones is described, which affords dihydrofuran‐3‐ones in good yields and with excellent enantioselectivities. The reaction is initiated by gold‐catalyzed alkyne oxidation and modification of the resulting gold carbene species with a tethered hydroxy group to form enolate species; the reaction terminates with an enantioselective Mannich‐type
methyleneindolinones and nitrones as the starting materials through [3+2] annulationcatalyzed by a bisthiourea. Products with three contiguous stereocenters, including one spiroquaternary stereocenter, are obtained in good yields with excellent enantio‐ and diastereoselectivity. The bisthiourea catalyst acts as a multiple‐hydrogen‐bond donor to simultaneously activate both substrates.
An unprecedented gold‐catalyzed dual annulation of homopropargyl alcohols with nitrones has been developed, which provides an effective access to the 1,3,4,5‐tetrahydropyrano[4,3‐b]indole derivatives in good to high yields. Mechanistically, this one‐pot three‐step cascade reaction is initiated by a gold‐catalyzed alkyne oxoarylation, followed by an intramolecular cyclodehydration and terminated with
与硝酮高炔丙基醇的前所未有的金催化的双环已被开发,这提供了有效的访问-1,3,4,5-四氢吡喃并[4,3- b ]吲哚衍生物以良好至高产率。从机理上讲,这种一锅三步的级联反应是由金催化的炔基羰基化反应引发的,然后进行分子内环脱水反应,并终止于醛间的分子间环化反应,而醛是该级联反应过程的早期残留物。
Construction of 1,2-dihydro-1,3,5-triazines <i>via</i> reactions involving amidines
作者:Honghong Guo、Jianying Lin、Qiang Liu、Xing Li
DOI:10.1039/d3ob00283g
日期:——
synthesized through three sets of reactions of amidines with, respectively, paraformaldehyde, aldehydes and N-arylnitrones under different conditions. The catalysts used in these three reactions were Cu(OAc)2, ZnI2 and CuCl2·2H2O, respectively. Most of the substrates tested for these reactions provided the target products in moderate to good yields. In the reactionsinvolving paraformaldehyde, Cu(OAc)2 also