Stereoselective total synthesis of the putative structure of nitraraine

Abstract

After the structure originally proposed for nitraraine was shown to be incorrect by total synthesis, the alternative structure 5 was recently suggested for the alkaloid on biosynthetic grounds and by comparison with the (1)H NMR data of tangutorine. The unambiguous synthesis of 5 is reported from tryptophanol and ketodiester 6, via oxazoloquinolone lactam 7. However, the melting point and (1)H NMR data of 5 did not match those reported for the natural product.