Vachan B S, Ramesh Aishwarya, Karuppasamy Muthu, Muthukrishnan Isravel, Nagarajan Subbiah, Menéndez J Carlos, Maheswari C Uma, Sridharan Vellaisamy
Department of Chemistry, School of Chemical and Biotechnology, SASTRA Deemed University Thanjavur-613401 Tamil Nadu India
Department of Chemistry, National Institute of Technology Warangal Warangal-506004 Telangana India.
RSC Adv. 2019 Oct 16;9(57):32946-32953. doi: 10.1039/c9ra07108c. eCollection 2019 Oct 15.
An oxidant-free three-component synthesis of biologically significant 7-amino-6-benzo[]chromen-6-ones was established involving a Sc(OTf) catalyzed three-component reaction between primary amines, β-ketoesters and 2-hydroxychalcones under green conditions. In this strategy, both the B and C rings of 6-benzo[]chromen-6-ones were constructed simultaneously starting from acyclic precursors by generating four new bonds including two C-C, one C-N and one C-O in a single synthetic operation. The mechanism of this sequential cascade process involves the initial formation of a β-enaminone intermediate followed by Michael addition with 2-hydroxychalcone, intramolecular cyclization, dehydration, lactonization and aromatization steps. Unlike the related literature approaches, this reaction delivered the products without the addition of any external oxidants to achieve the key aromatization step.
建立了一种无氧化剂的三组分合成具有生物学意义的7-氨基-6-苯并[]色烯-6-酮的方法，该方法涉及在绿色条件下，由钪（III）三氟甲磺酸盐催化伯胺、β-酮酯和2-羟基查耳酮之间的三组分反应。在该策略中，6-苯并[]色烯-6-酮的B环和C环均由无环前体同时构建，通过在单一合成操作中生成四个新键，包括两个C-C键、一个C-N键和一个C-O键。这种连续级联过程的机制包括首先形成β-烯胺酮中间体，随后与2-羟基查耳酮进行迈克尔加成反应、分子内环化反应、脱水反应、内酯化反应和芳构化反应步骤。与相关文献方法不同的是，该反应无需添加任何外部氧化剂即可完成关键的芳构化步骤，从而得到产物。
