炭素-炭素単結合の活性化を基盤とする新合成手法の開拓

Abstract

Carbon-carbon single bonds constitute the main frameworks of organic molecules. They are non-polar, thermodynamically stable, and kinetically inert in general. Nonetheless, it would streamline synthetic pathways if carbon-carbon single bonds are subjected to site-selective cleavage and directly utilized for construction and/or functionalization of organic skeletons. We herein describe the synthetic methods we have developed based upon carbon-carbon bond activation during the past four years. Rhodium(I) complexes cleave the carbon-carbon bond of strained tert-alcohols by β-carbon elimination to generate organorhodium(I) intermediates, and thus trigger reconstruction of their frameworks into totally different ones with excellent atom economy. These reactions are combined with Norrish-Yang type photo-reactions to make thermodynamically disfavored transformations possible. Ring expansion of orthocyclophanes to metacyclophanes and enantioselective synthesis of 3-hydroxyindolines from α-(N-aryl)amino ketones present prototypical examples of organic synthesis driven by photo-energy. Also described is a restructuring reaction of N-arenesulfonylazetidinols into benzosultams.