Abstract
We report an unexpected rearrangement of 3-hydroxyoxindoles into benzoxazinones using electrochemistry. Our reaction employs mild and environmentally friendly conditions, and the benzoxazinone products are obtained in moderate to excellent yields. Mechanistic experiments suggest that a peroxide intermediate is likely involved.
Highlights
We report an unexpected rearrangement of 3-hydroxyoxindoles into benzoxazinones using electrochemistry
Given the prevalence of this motif in medicinal chemistry, there remains a general need for divergent methodologies that facilitate the preparation of a range of benzoxazin-2-one derivatives to support drug discovery
Other approaches form the desired carbamates either by double-lithiation of a transient urea, formed from an isocyanate, followed by reaction with an aldehyde,[4] or by an aminolysis−Hofmann rearrangement starting from phthalides[5] (Scheme 1B, right)
Summary
Water and atmospheric oxygen were ruled out as possible sources after it was found that neither the addition of molecular sieves, water, or molecular oxygen nor conducting the reaction under an inert atmosphere with degassed solvents had a significant impact on the yield (Scheme 3, eq 1) These results highlight the robustness of our protocol which proved to be tolerant of water as well as oxygen. In the presence of additional methylamine, 1 is converted into a 3,3-disubstituted quinazolinone derivative 10 in 64% yield (Scheme 5) This result, reminiscent of that obtained with K2CO3 (cf Scheme 3, eq 3), can be explained by the basic character of methylamine, enabling possible fragmentation of the perox-.
Sign-in/Register to view highlights & summary 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 callSimilar Papers
Disclaimer: 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.
