SYNTHESIS OF 2,3-DIHYDRO-8-(3-HYDROXY-3-METHYLBUT-1-ENYL)-7-METHOXY-2-PHENYL-4H-1-BENZOPYRAN-4-ONE - A NOVEL STRUCTURE FOR FALCIFORMIN

Synthesis of 2,3-dihydro-8-(3-hydroxy-3-methylbut-l-enyl)-7-methoxy-2-phenyl-4if-l-benzopyran-4-one (1) has been achieved in order to verify the proposed structure of falciformin, a new constituent of Tephrosia falciformis. The melting point and spectral characteristics of synthetic 1 are not consistent with those reported for the natural sample, thereby showing that the proposed structure is erroneous. Based on the data reported for the natural product, the new structure 2,3-dihydro-5-(l,l-dimethyl-2-hydroxyprop-2-enyl)-6-methoxy-2-phenyl-4H-l-benzopyran-4-one (4) is tentatively proposed for falciformin. The mass spectral fragmentation patterns of 1 and 4 are discussed in detail in support of their structures. © 1990, American Chemical Society. All rights reserved.