Minor Coumarins from <i>Calophyllum teysmannii</i> var. <i>inophylloide</i> and Synthesis of Cytotoxic Calanone Derivatives

Abstract

Abstract A Chemotaxonomic survey for biologically active compounds from Malaysian Calophyllum species led to the findings of the four new benzoylcoumarins 1a , 2 , 3 , and 4a (including the unusual prenylated 6‐benzoylcoumann 1a ), two uncommon coumarins 5 and 6a with a pyran‐4‐one moiety fused at C(6) and C(7), and compounds 7a , 9 , and 10 , all isolated from the bark of C. teysmannii var. inophylloide . Their structures were determined by spectroscopic analysis and chemical transformations. X‐Ray crystal‐structure determination of 2 provided information on the conformational preferences of substituents in this class of coumarins. The syntheses of the cytotoxic calanone ( 7a ) and of some related coumarins are described.