Zn(OTf)<sub>2</sub>-Catalyzed Formal [3 + 3] Cascade Annulation of Propargylic Alcohols with 2-Aminochromones: Accessing the Chromeno[2,3-<i>b</i>]pyridines
作者:Pei Tong、Zhou Sun、Shutao Wang、Yuan Zhang、Ying Li
DOI:10.1021/acs.joc.9b02120
日期:2019.11.1
A Zn(OTf)2-catalyzed formal [3 + 3] cascade annulation strategy for the synthesis of functionalized chromeno[2,3-b]pyridines has been developed using propargylicalcohols and 2-aminochromones as the substrates. The protocol provides a convenient and atom-economical method of accessing a broad range of chromeno[2,3-b]pyridine derivatives in excellent yields with good functional-group tolerance. The
Synthesis of 2-(2-hydroxybenzoyl)-4H-furo[3,2-c]chromen-4-one has been accomplished by the reaction of 3-halochromone with 2-aminochromone. In this reaction, 2-aminochromone acts as a masked 4-hydroxycoumarin.
A DDQ-mediated tandem annulation of 2-aminochromones with 1,3-diarylpropenes is disclosed, which provides the azaxanthones in moderate to good yields. The oxidative coupling, intramolecular cyclization and dehydro-aromatization might be involved in this high atom-efficiency reaction.
One-pot synthesis of chromeno[2,3-<i>b</i>]isoindolo[1,2-<i>e</i>]pyrrole-12,13-dione derivatives by sequential reaction of ninhydrin, 2-aminochromen-4-ones and arylamines
ABSTRACT Stirring an equimolar mixture of ninhydrin 1 and 2-aminochromen-4-ones 2 in CH3COOH at room temperature produced 6a,11a-dihydroxy-6H-chromeno[2,3-b]indeno[2,1-d]pyrrole-11,12(6aH,11aH)-diones 3, which on heating with aromatic amines 6 in acetic acid produced 11b-hydroxy-7-N-arylimino-6H-chromeno[2,3-b]isoindolo[1,2-e]pyrrole-12,13(11bH)-diones 7. GRAPHICAL ABSTRACT
Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine: synthesis of novel RF-containing isoxazole and chromone derivatives
作者:Vyacheslav Ya. Sosnovskikh、Vladimir S. Moshkin、Mikhail I. Kodess
DOI:10.1016/j.tet.2008.06.041
日期:2008.8
Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine free base proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4H-chromeno[3,4-d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones, which
3-(多氟酰基)发色酮与羟胺游离碱的反应通过亲核的1,4-加成反应进行,随后打开吡喃环并随后环化为4-(多氟烷基)-4 H-苯并[3,4- d ]异恶唑- 4-醇收率良好。用三氟乙酸处理时,该环状杂环系统的异恶唑环打开,得到3-氰基-2-(聚氟烷基)色酮,将其成功地用浓H 2 SO 4水解,得到3-氨基甲酰基-2-(聚氟烷基)色酮。 。另一方面,用羟胺盐酸盐对3-(聚氟酰基)色酮进行肟化反应是在与R F基团相连的羰基碳原子上或在C-2原子上发生的,从而得到3-R F。C(NOH)-色酮和5-R F -4-水杨酸异恶唑肟。通过简单地在二甲基亚砜中加热,将前者容易地转化为3-R F -4-水杨酸异恶唑。