Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins
作者:Christiane Schultze、Bernd Schmidt
DOI:10.3762/bjoc.14.278
日期:——
conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination/cyclizationsequence. They serve as a versatile platform for the annellation of five- to seven-membered rings using ring-closing olefin metathesis (RCM). Furano-, pyrano-, oxepino- and azepinocoumarins were synthesized from the same set of precursors using Ru-catalyzed double bond isomerizations and RCM in a defined
Zeolite‐promoted Synthesis of Coumarins and Thiocoumarins
作者:Olesia Zaitceva、Valérie Bénéteau、Dmitry S. Ryabukhin、Benoit Louis、Aleksander V. Vasilyev、Patrick Pale
DOI:10.1002/cctc.201901384
日期:2020.1.8
Acidic zeolites, especially faujasites, efficientlypromote the intramolecular cyclization of aryl propynoates and propynethioates, which produces coumarins and thiocoumarins, usually in high yields. Comparison with homogeneous Lewis or BrØnsted acids and with heterogeneous related sieve materials revealed the prevalence of zeolites exhibiting large cage‐type pores (H‐USY) for such cyclizations. Various