Copper(II)-Catalyzed Alkoxyhalogenation of Alkynyl Ureas and Amides as a Route to Haloalkylidene-Substituted Heterocycles
摘要:
A highly effective synthesis of haloalkylidene-substituted heterocycles by copper(II)-catalyzed cyclization of alkynyl ureas and secondary amides has been developed. The reaction, which involves a catalytic amount of CuCl2 and a stoichiometric amount of N-halosuccinimide, occurs selectively through an alkoxyhalogenation process. Alternatively, alkoxychlorination and alkoxybromination reactions can be performed working solely with stoichiometric CuCl, and CuBr2, respectively.
Sulfur-Fluoride Exchange (SuFEx)-Mediated Synthesis of Sterically Hindered and Electron-Deficient Secondary and Tertiary Amides via Acyl Fluoride Intermediates
作者:Christopher J. Smedley、Andrew S. Barrow、Christian Spiteri、Marie-Claire Giel、Pallavi Sharma、John E. Moses
DOI:10.1002/chem.201701552
日期:2017.7.26
Amide bond formation is one of the most executed reactions in chemistry and biology. This is largely due to the ubiquity of the amide functional group in biological molecules, natural products and pharmaceutically important drugs. We report here the development of “SuFExAmide”: a new sulfur–fluoride exchange (SuFEx) click chemistry based protocol for the efficient amidation of carboxylic acids via
A palladium-catalyzed process to construct oxazoles and oxazolines with broad functional-group tolerance has been developed, and the method introduces difluoromethyl groups into heterocycles in a one-pot fashion. This system uses a carbonyl oxygen as the acceptor for the addition of a vinylpalladium intermediate to achieve the cyclization. Oxazoline derivatives are generated as the Z-isomer with high
Cyclobutene Formation in PtCl<sub>2</sub>-Catalyzed Cycloisomerizations of Heteroatom-Tethered 1,6-Enynes
作者:Zhenjie Ni、Laurent Giordano、Alphonse Tenaglia
DOI:10.1002/chem.201403643
日期:2014.9.8
Aza(oxa)bicyclo[3.2.0]heptenes are accessed through the PtCl2‐catalyzed cycloisomerizations of heteroatom‐tethered 1,6‐enynes featuring a terminal alkyne and amide as the solvent. It is shown that the weak coordinating properties of the solvent and alkyl substituent(s) at the propargylic carbon atom favor the formation of cyclobutenes instead of other possible cycloisomerization products such as 1
[reaction: see text] 2,5-Disubstituted oxazoles have been prepared through the reaction of N-propargylamides with aryl iodides in the presence of Pd(2)(dba)(3), tri(2-furyl)phosphine, and NaO(t)()Bu. The reaction appears to proceed through a palladium-catalyzed coupling step followed by the in situ cyclization of the resultant coupling product.
Iodine-promoted cyclization of N-propynyl amides and N-allyl amides via sulfonylation and sulfenylation
作者:Gopal Chandru Senadi、Bing-Chun Guo、Wan-Ping Hu、Jeh-Jeng Wang
DOI:10.1039/c6cc05138c
日期:——
Iodine-promoted sulfonylation of N-propynyl amides with sulfonyl hydrazides followed by DBU mediated cyclisation to afford 5-methyl-arylsulfonyloxazoles and oxysulfenylation of N-allyl amides through electrophilic addition of in situ generated sulfenyl iodide...