Photochemical transformations of small ring heterocyclic compounds. 91. Photochemistry of the chroman and 3-chromanone ring systems. An example of tautomeric control of excited-state chemistry
Novelroute for the construction of chromans from benzylic and aliphatic alcohols in the presence of NaHSO4/SiO2 has been developed. In this reaction, substituted olefins are formed from benzylic and aliphatic alcohols and then converted to chromans through intramolecular cyclization. Twenty novel chromans were synthesized by this simple procedure.
Multicomponent Condensation Reactions via <i>ortho</i>-Quinone Methides
作者:Emily E. Allen、Calvin Zhu、James S. Panek、Scott E. Schaus
DOI:10.1021/acs.orglett.7b00647
日期:2017.4.7
with electron-rich phenols to generate ortho-quinonemethides that undergo Diels—Alder condensations with alkenes. The reaction sequence occurs in a single vessel to afford benzopyrans in up to 95% yield. The reaction was discovered while investigating a two-component strategy using 2-(hydroxy(phenyl)methyl)phenols to access the desired ortho-quinonemethide in a Diels—Alder condensation. The two-component