Catalyst-Free Intramolecular Oxidative Cyclization of N-Allylbenzamides: A New Route to 2,5-Substituted Oxazoles
摘要:
A catalyst-free intramolecular oxidative cyclization reaction of N-allylbenzamides has been developed to prepare 2,5-disubstituted oxazoles with good yields. This reaction gives an efficient synthetic strategy to form an oxazole nucleus directly from easily accessible substrates under temperate conditions.
Pd(II)-Catalyzed, Picolinamide-Assisted, Z-Selective γ-Arylation of Allylamines To Construct Z-Cinnamylamines
摘要:
Investigations of Pd(II)-catalyzed, picolinamide-assisted, gamma-C(sp(2))-H activation and Z-selective arylation of allylamines are reported. The reactions of N-allylpicolinamides with various aryl iodides in the presence of the catalyst Pd(OAc)(2) and additive AgOAc have led to the selective gamma-arylation of allylamines to construct various cinnamylamines with moderate to good yields and good to high E/Z ratios. To obtain good E/Z ratios, the Pd(II)-catalyzed arylation reaction of N-allylpicolinamides was probed using different additives, directing groups, and reaction conditions. The Pd(II)-catalyzed arylation of an allylamine containing both gamma-C(sp(2))-(H) and gamma-C(sp(3)) H bonds afforded moderate yields of the gamma-C(sp(2)) H and gamma-C(sp3) H bisarylated cinnamylamines. Although Heck-type gamma-arylations of allylamines have generally afforded the E-cinnamylamines, the bidentate directing group picolinamide-directed arylations of allylamines were found to be Z-selective. A plausible mechanism was proposed for the observed regioselectivity and Z-selective arylation of N-allylpicolinamides. Additionally, the Pd(II)-catalyzed arylation of an N-allyl-5-methylisoxazole-3-carboxamide afforded the E-cinnarnylamines plausibly via a ligand-free Heck-type reaction mechanism.
Metal-Free Oxidative Functionalization of C(sp<sup>3</sup>)–H Bond Adjacent to Oxygen and Radical Addition to Olefins
作者:Wei Zhou、Ping Qian、Jincan Zhao、Hong Fang、Jianlin Han、Yi Pan
DOI:10.1021/acs.orglett.5b00088
日期:2015.3.6
A DTBP-promoted oxidative functionalization of a C(sp3)–Hbond adjacent to oxygen and intermolecular radical addition to olefins without use of any metal catalyst or photoredox catalysis is reported. The reaction has a wide scope of olefin, alcohol, and cycloether substrates, which provides an easy way for direct preparation of α,ω-amino alcohols.
Mercurial Diuretics. II. Methoxymercuration of N-Allyl Amides
作者:R. L. Rowland、Wendell L. Perry、Samuel Gerstein
DOI:10.1021/ja01145a033
日期:1951.1
Preparation of Heterocycles via Visible-Light-Driven Aerobic Selenation of Olefins with Diselenides
作者:Qing-Bao Zhang、Pan-Feng Yuan、Liang-Lin Kai、Kai Liu、Yong-Liang Ban、Xue-Yang Wang、Li-Zhu Wu、Qiang Liu
DOI:10.1021/acs.orglett.8b03738
日期:2019.2.15
The aerobic dehydrogenative cyclization of alkenes with easily accessible diselenides facilitated by visible light is reported. Notably, the features of this transition-metal-free protocol are pronounced efficiency and practicality, good functional group tolerance, atom economy, and high sustainability, since ambient air and visible light are adequate for the clean construction of five- and six membered heterocycles in yields of up to 98%.