Palladiumkatalysierte Kreuzkupplungen in der Totalsynthese

SNF4435C and D, novel nitrophenyl pyrones, have been isolated from the culture broth of an actinomycete strain SNF4435. The strain was identified as Streptomyces spectabilis from its morphological and cultural characteristics. SNF4435C and D showed a potent immunosuppressive activity in vitro and selectively suppressed B-cell proliferation induced by LPS versus T-cell proliferation induced by Con A.

SNF4435C and D are new immunosuppressants isolated from the culture broth of a strain of Streptomyces spectabilis. Their molecular formulas were determined as C28H31NO6 based on the HRFAB-MS analyses. The structures of SNF4435C and D were elucidated to be novel nitrophenyl pyrones having an intriguing tricyclic ring system and diastereoisomers of each other by spectroscopic analyses including various NMR measurements.