Exploiting Hydrazones To Improve the Efficiency of 6π-Electrocyclization Reactions of 1-Azatrienes
作者:Matthew P. Ball-Jones、Jasper Tyler、Helena Mora-Radó、Werngard Czechtizky、María Méndez、Joseph P. A. Harrity
DOI:10.1021/acs.orglett.9b02455
日期:2019.9.6
The greater geometric lability of hydrazones compared to that of oximeethers is used as a basis to overcome the reluctance of Z-oxime ether azatrienes to undergo electrocyclization toward the synthesis of borylated (heteroaromatic) pyridines and ring-fused analogues. Such hydrazones now allow access to previously inaccessible tri- and tetrasubstituted 3-borylpyridines in high yields.
Rhodium(II)-Catalyzed Cyclization of Bis(N-tosylhydrazone)s: An Efficient Approach towards Polycyclic Aromatic Compounds
作者:Ying Xia、Zhenxing Liu、Qing Xiao、Peiyuan Qu、Rui Ge、Yan Zhang、Jianbo Wang
DOI:10.1002/anie.201201374
日期:2012.6.4
Ahead of the PAC: Polycyclicaromaticcompounds (PACs) can be easily accessed by the combination of Suzuki–Miyaura cross‐coupling and a [Rh2(OAc)4]‐catalyzed carbene reaction using easily available bis(N‐tosylhydrazone)s as intermediates (see scheme; Ts=4‐toluenesulfonyl).
Metal-free visible light-promoted synthesis of isothiazoles: a catalytic approach for N–S bond formation from iminyl radicals under batch and flow conditions
applying photoredoxcatalysis. This simple strategy features mild conditions, broad scope and wide functional group tolerance representing a new enviromentally friendly option to prepare these highly valuable heterocycles. Furthermore, the synthetic value of the method is highlighted by the preparation of a natural product derivative and the implementation of the reaction in a continuousflow setup.
A base-promoted formal [2 + 2]-cycloaddition of 2-acyl-2′-vinyl-1,1′-biaryls was developed to provide polycyclic cyclobutanols as a step toward the synthesis of substituted polycyclic aromatic hydrocarbons and their heterocyclic analogues.
An Efficient Gold-Catalyzed Domino Process for the Construction of Tetracyclic Ketoethers
作者:Tobias Groß、Peter Metz
DOI:10.1002/chem.201302985
日期:2013.10.25
Au, yeah! Catalytic amounts of gold(III)chloride allow a mild and efficient oxidative domino cyclization/cycloaddition of enyne carbonyl compounds 1 and 4 to give the tetracycles 2 or 5, respectively, in the presence of pyridine N‐oxide 3 (see scheme; DCE = 1,2‐dichloroethane).