Abstract
The epoxyimine (11a), derived from berberinium chloride, smoothly gives the naphthoquinone epoxide (25a) via several steps. The site-selective reduction of 25a with lithium tri-tert-butoxyaluminohydride affords the cis-epoxy ketol (27a) (45%) and trans isomer (28a) (38%) which result from the attack of the reducing agent at the 4-position. Further reductions of 27a and 28a with sodium borohydride provide the cis-dihydroxy epoxide (32a) and trans isomer (29a), respectively, as a sole product in each case. The desired compounds having the 1-hydroxyl groups trans with respect to the oxirane rings are not formed. Treatment of 32a with methylamine results in the formation of the amide (33a), which is transformed to the isoindolinone (34) and phthalide (35) during purification by preparative thin-layer chromatography using silica gel. The epoxyimine (11b), derived from protopine, gives similar results. The correlation between the proton magnetic resonance data and the structures of the compounds obtained is briefly discussed.
Sign-in/Register to access full text options 
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.
