To improve the efficiency of the photocatalytic decarbonylation of cyclopropenones, the effects of substituents on cyclopropenone were explored. A benzothiophene-substituted aminocyclopropenone exhibited significantly improved decarbonylation efficiency to produce the corresponding ynamine, which worked as a potent dehydration condensation agent. The benzothiophene derivative was applicable to the
Ammonia-borane as a Catalyst for the Direct Amidation of Carboxylic Acids
作者:P. Veeraraghavan Ramachandran、Henry J. Hamann
DOI:10.1021/acs.orglett.1c00591
日期:2021.4.16
Ammonia-borane serves as an efficient substoichiometric (10%) precatalyst for the direct amidation of both aromatic and aliphatic carboxylicacids. In situ generation of amine-boranes precedes the amidation and, unlike the amidation with stoichiometric amine-boranes, this process is facile with 1 equiv of the acid. This methodology has high functional group tolerance and chromatography-free purification
Hydroamidation of olefins constitutes an ideal, atom-efficient method to prepare carboxylic amides from easily available olefins, CO, and amines. So far, aliphatic amines are not suitable for these transformations. Here, we present a ligand- and additive-free Rh(I) catalyst as solution to this problem. Various amides are obtained in good yields and excellent regioselectivities. Notably, chemoselective
The electronic effects of tetranuclear zinc cluster catalysts on transesterification were investigated by changing the carboxylate ligands in the clusters. High catalyst activity crucially depended on the balance between Lewis acidity and Brønsted basicity of the catalyst; this was consistent with the dual activation of both the electrophile and nucleophile by the cooperative zinc centers. In addition
A Novel Dehydrazination Reaction. V. The Formation of Various Amides from Aliphatic and Aromatic Carboxylic Acid Hydrazides in the Presence of Chloral
作者:Tetsuji Kametani、Osamu Umezawa
DOI:10.1248/cpb.14.369
日期:——
In the previous papers the reactions between aromatic, aliphatic and heterocyclic carboxylic acid hydrazides and either chloral or bromal in various alcohols were attempted and respective esters were obtained. In this paper the reactions of aromatic and aliphatic acid hydrazide with chloral in the presence of various amines were examined, leading eventually to reveal the formation of our expected acid amides as are shown in Table I and II. The intermediates in this reaction, 1-benzoyl-2-(2, 2, 2-trichloroethylidene) hydrazine (III : R=C6H5-, X=Cl) was found to form the amides (VI) when heated in amines. This fact indicated that the acid hydrazides converted to their amides through III.