cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO4)2 complex of an N,N′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1
Ligand-free Cu(<scp>ii</scp>)-mediated aerobic oxidations of aldehyde hydrazones leading to N,N′-diacylhydrazines and 1,3,4-oxadiazoles
作者:Lei Liu、Suliu Feng
DOI:10.1039/c7ob00042a
日期:——
A Cu(II)-mediated synthesis of N,N′-diacylhydrazines and 1,3,4-oxadiazoles from aldehyde hydrazones has been developed. This is the first time that the synthesis of N,N′-diacylhydrazines and 1,3,4-oxadiazoles using N,N-dimethylamides as the acylation reagent and O2 in air as the oxidation reagent is reported. These reactions offered several advantages including simple workups, ligand-free inexpensive
cyclization protocol employing cobalt nitrate and 1,2‐dichloroethane to produce substituted 1H‐1,2,4‐triazoles. Notably, 1,2‐dichloroethane serves both the solvent and a hydrogen source for transfer hydrogenation. This methodology works under mild conditions, providing a direct approach for the synthesis of 1H‐1,2,4‐triazoles.
A novel sequential [3+2] annulation reaction has been developed using prop-2-ynylsulfonium salts and hydrazonyl chlorides, affording a series of pyrazoles with functional motifs that can be post modified in the preparation of various drugs or drug candidates. Further transformation and gram-scale operations could also be achieved efficiently.
Hydrazone Phosphaketene as a Synthetic Platform To Obtain Three Classes of 1,2,4-Diazaphosphol Derivatives by Switchable Chemoselectivity Strategies
作者:Xin Wang、Dong-Ping Chen、Wen-Peng Wang、Chun-Hong Yang、Ming Li、Wen-Bo Xu、Xi-Cun Wang、Zheng-Jun Quan
DOI:10.1021/acs.orglett.4c00993
日期:2024.5.3
classes of 1,2,4-diazaphosphol derivatives. First, the five-membered heterocyclic P and O anion intermediates acted as nucleophilic agents in the selective construction of C–P and C–O bonds. Second, the phosphinidene served as a phosphorus synthon, allowing for the formation of C–P and C–N bonds. Finally, a stepwise mechanism, supported by DFT calculations, was invoked to explain the reaction selectivity