Generation and in situ acylation of enaminone anions: a convenient synthesis of 3-carbethoxy-4(1H)-pyridinones and -4-pyrones and related compounds
作者:Stuart W. McCombie、William A. Metz、Dennis Nazareno、Bandarpalle B. Shankar、Jayaram Tagat
DOI:10.1021/jo00016a028
日期:1991.8
Treatment of 2-[(dimethylamino)methylene]-3-oxobutanoates 9 or 10 with LiN(SiMe3)2 in the presence of RCOCl results in C-acylation. The resulting intermediate, without isolation, may be converted to 6-R 3-Carbethoxy-4-pyrones (e.g., 12) by H3O+ or to the corresponding pyridinones (e.g., 13) by NH4OAc. Typically, yields are 55-75% for R groups lacking acidic alpha or gamma protons and ca. 30% for R = Me2CH or MeCH = CH. Replacing 9 with MeCOC(= CHNMe2)SCH2Ph (from MeCOCH2SCH2Ph and Me2NCH(OMe)2 similarly affords 3(PhCH2S)-substituted products such as 29. Alkylation of the pyridinone anions produces mixtures of N- and O-substituted compounds, with the latter predominating; aminolysis of the isolated pyrones (R'NH2-HOAc, where R' = alkyl, Ar, HO, etc.) is the preferred route to the 1-R'-substituted pyridinones.
Synthesis and Evaluation of Novel Nonpeptide Angiotensin II Receptor Antagonists: Imidazo(4,5-c)pyridine Derivatives with an Aromatic Substituent.
prepared a new series of 6-arylimidazo[4,5-c]pyridine derivatives. Variation of phenyl groups at the 4-, 6- or 7-position of imidazo[4,5-c]pyridine showed that substitution at the 6-position resulted in receptor-binding activity almost as potent as that of DuP 753. This led to synthesis and evaluation of an extensive series of 6-aryl-imidazo[4,5-c]pyridine derivatives. Some of them were 4-fold more potent
Access to Chromenopyrrolidines Enabled by Organophotocatalyzed [2 + 2 + 1] Annulation of Chromones with <i>N</i>-Arylglycines
作者:Xin Zhou、Biwei Zhang、Ping Wu、Wei Xu、Renqi Wang、Jingbai Li、Hongbin Zhai、Bin Cheng、Taimin Wang
DOI:10.1021/acs.orglett.3c02801
日期:2023.10.20
conditions via organophotocatalyzed aerobic decarboxylative [2 + 2 + 1] annulation of chromones with N-arylglycines, in which N-arylglycines perform dual roles (i.e., radical precursor and methylene provider). Mechanistic studies suggested that a Giese-type radical addition and consequent Mannich pathway were likely responsible for the annulation reaction.