Abstract
AbstractDiels–Alder (DA) cycloadditions of 5‐hydroxy‐2‐pyrones based on the use of 2H‐pyran‐2,5‐diones and 5‐(tert‐butyldimethylsilyloxy)‐2‐pyrones as synthons have been developed. Upon treatment either with a base or with a Lewis acid, 2H‐pyran‐2,5‐diones equilibrated to 5‐hydroxy‐2‐pyrones and underwent DA cycloaddition. The base‐catalyzed protocol was optimized with cHex2NMe (0.1 equiv.) in tBuOH at room temperature, which gave the bicyclic cycloadducts in yields of up to 81 % (endo/exo = 6.2:1). The Lewis‐acid‐promoted protocol was optimized by conversion of 2H‐pyran‐2,5‐diones into 5‐(tert‐butyldimethylsilyloxy)‐2‐pyrones and use of BF3·OEt2, which afforded the same DA products in yields of up to 90 % (endo/exo = 12:1).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
