Tandem Palladium/Charcoal-Copper(I) Iodide (Pd/C-CuI) Catalyzed Sonogashira Coupling and Intramolecular Cyclization from 2-Bromonicotinic Acid (=2-Bromopyridine-3-carboxylic Acid) and Ethynylarenes to 4-Azaphthalides (=Furo[3,4-b]pyridin-5(7H)-ones) and 5
作者:Agathe Begouin、Maria-João R. P. Queiroz
DOI:10.1002/hlca.201100060
日期:2011.10
Pd/CPh3PCuI and Et3N in dry dioxane under Ar at 90°, a mixture of 4‐azaphthalides (usually the major product) and 5‐azaisocoumarins was obtained after 3.5 h under normal heating (Schemes 3 and 4; Tables 1 and 2). This mixture of compounds was also obtained with the same catalytic system undermicrowave (MW) irradiation in only 25 min (Tables 3 and 4). The 1‐ethynyl‐3‐methoxybenzene gave on heating only the corresponding
制备了几种4-氮杂酞(=呋喃[3,4- b ]吡啶-5(7 H)-one)和5-氮杂异香豆素(= 5 H-吡喃并[4,3 - b ]吡啶-5 -one ) Pd / C介导的Sonogashira串联异质偶联以及2-溴烟酸(= 2-溴吡啶-3-羧酸)与各种乙炔基芳烃或3-乙炔基噻吩的5 exo-dig或6 -endo分子内环化反应。在Pd / C的存在下博士3 P 的CuI和Et 3在90°C的Ar下于干燥的二恶烷中的N,在常规加热下3.5 h后获得4-氮杂酞(通常是主要产物)和5-氮杂异香豆素的混合物(方案3和4;表1和2)。在仅25分钟的微波(MW)辐照下,也用相同的催化系统获得了该化合物的混合物(表3和4)。1-乙炔基-3-甲氧基苯仅加热加热相应的4-氮杂萘化物(表2),而在MW照射下,获得了5 -exo-dig和6 -endo-dig产物(表4))。对于3-乙炔基噻吩,两种方法
NHC-Catalyzed Oxidative Cyclization Reactions of 2-Alkynylbenzaldehydes under Aerobic Conditions: Synthesis of O-Heterocycles
作者:Jong Hyub Park、Sachin V. Bhilare、So Won Youn
DOI:10.1021/ol200481u
日期:2011.5.6
An NHC-catalyzed, regio- and stereoselective oxidative cyclization of o-alkynylbenzaldehydes bearing an unactivated alkyne moiety as an internalelectrophile has been developed to afford phthalides and isocoumarins. A single organocatalytic system enabled two sequential C−O bond formations to take place in an atom economical manner via highly efficient dual activation. Molecular oxygen in air could