The First Example of Di--Methane Rearrangement in Nature: Cephalotanols A and B, Two Novel Rearranged Norlignan Glycosides from Cephalotaxus fortunei Hook

Abstract

: A pair of unique diastereoisomers of norlignan glycosides named cephalotanols A ( 1 ) and B ( 2 ), together with two known compounds, have been isolated from the twigs and leaves of Cephalotaxus fortunei Hook. Their structures were elucidated by using a combination of spectroscopic techniques and comparison of experimental and calculated electronic circular dichroism (ECD) data. To our knowledge, cephalotanols A and B represent the first rearranged norlignan glycosides with diphenylvinylcyclopropane core found in natural sources, of which biosynthetic pathways originating from co-occurring precursors 3 S -4  - O -  - D - glucopyranosylhinokiresinol ( 3 ) and 3 S -4  - O -  - D -glucopyranosylhinokiresinol ( 4 ) via di-  -methane rearrangement is proposed.