Inside Back Cover

Cobalt, as a naturally highly abundant first row (3d) transition metal, has emerged as versatile, efficient and less toxic catalyst for C—H bond activation to construct polycyclic molecular frameworks. The cover image depicts the selective synthesis of spiro indene-2,1'-isoindolinones and spiro isochroman-3,1'-isoindolinones via cobalt-catalyzed switchable [4 + 1] and [4 + 1 + 1] spirocyclization of aromatic amides with 2-diazo-1H-indene-1,3(2H)-dione. More details are discussed in the article contributed by Li and Fan et al. on page 363—369.