Preparation of Heteroaromatic (Aryl)iodonium Imides as I−N Bond-Containing Hypervalent Iodine
作者:Kazuma Ishida、Hideo Togo、Katsuhiko Moriyama
DOI:10.1002/asia.201601349
日期:2016.12.19
Hypervalent iodine(III) compounds containing iodine–nitrogen bonds are very attractive amination reagents in organic synthesis. Heteroaromatic (aryl)iodonium imidescontaining a iodine–nitrogen bond and a hypervalent iodine(III) atom were prepared from heteroarenes, bis(sulfon)imides and (diacetoxyiodo)arenes under mild conditions. These compounds were stable under air and in organic solvents, and
Copper-catalyzed C–N cross-coupling of arylboronic acids with N-acylpyrazoles
作者:Jin Zhang、Run-Ping Jia、Dong-Hui Wang
DOI:10.1016/j.tetlet.2016.06.044
日期:2016.8
A copper-catalyzed C–N bond forming reaction of arylboronicacids and N-acylpyrazoles was developed. This procedure used N-acetyl protected pyrazoles as starting material instead of free pyrazoles (NH). The reaction worked under neutral conditions and did not require any base or ligand. The reaction showed good functional group tolerance.
Diastereoselective .alpha.-Alkylation of 2-Acyl-3-phenyl-l-menthopyrazoles
作者:Choji Kashima、Iwao Fukuchi、Akira Hosomi
DOI:10.1021/jo00104a045
日期:1994.12
N-Acylpyrazoles were alpha-alkylated in good yields by the treatment with alkyl halides after metalation with LDA or LiHMDS, In the case of chiral N-acylpyrazoles, e.g., 2-acyl-3-phenyl-l-menthopyrazoles (4), the alpha-alkylation was highly diastereoselective. The subsequent alpha-alkylation products could be converted into esters in good yield in the presence of BF3.OEt(2) without the loss of the optical purity.
The Preparation of<i>N</i>-Acylpyrazoles and Their Behavior Toward Alcohols
According to four different methods, various types of N-acylpyrazoles were prepared from the corresponding pyrazoles and carboxylic acids or their acid chlorides. Although N-acylpyrazoles were inert to alcohols under neutral or weakly basic conditions, the alcoholysis was dramatically accelerated by the action of strong acid or base. On the basis of these chemical properties, the regioselective synthesis of methyl benzyl 2,2-dimethylglutarate was achieved by selective protection and functionalization of a carboxylic acid derivative using N-acylpyrazoles.