Final Report Summary - NSR-ANP (New Synthetic Reactions for Antitumor Natural Products)
Parallel efforts towards the installation of nitrogen atom functionalities into organic molecules triggered the recent discovery of a straightforward intermolecular carboamination methodology. A thioether substituent in readily accessible 2-alkyl-5-(methylthio)tetrazoles enables facile photoinduced denitrogenation and intramolecular nitrile imine 1,3 dipolar cycloaddition to afford a wide range of polycyclic pyrazoline products with excellent diastereoselectivity. The methylthio group obviates the requirement in all previous substrate systems for at least one aryl substituent and can subsequently be converted into a variety of other functionalities. This synthetic platform has been applied to the concise total syntheses of the alkaloid natural products (±) newbouldine and withasomnine.