Palladium Participitaed Ring-opening-cyclization Cascades Of O-bromoarylcyclobutanones En Route To Benzospirocycles

Carbon-carbon bonds are widely present in organic compounds.Based on its inertness and diversity in compounds,highly selective C-C bond activation is one of the hot and difficult topics in the field of organic chemistry.The chemical conversion process can provide new ideas and methods for organic reaction research and organic synthetic chemistry.In this paper,the release of the ring-strain of four-membered rings facilitates the C-C bond cleavage.O-bromoaryl cyclobutanones as the substrates,the addition of carbonyl sites of cyclobutanone to the occurrence of ?-carbon elimination under the catalysis of transition metals,leading to benzocyclopentanone intermediate,and further reaction with dba to give benzospiro compounds.The compounds are important bioactive molecules,and showed well-defined apoptotic and differentiation activity,making them potential leads for development as new anticancer agents and as chemical probes.We disclosed the first intramolecular C–Br bond triggered ring opening reaction of arylcyclobutanones,distinct from related reports in which the reactions were initiated by arylboron,silane or unsaturated chemical motifs,among others.The research is of great significance to the ring opening reaction of cyclobutanone and the activation of carbon-carbon bonds,and provides a new design idea for the synthesis of benzospiro compounds.Benzospirocyclic skeleton plays a key role in many functional compunds and drug molecules.Based on our previous work,the derivatization of the products was conducted by Wittig reaction.Several non-respond benzospiro compounds were synthesized,turning their structure into characterization.This further verifies the research value of the chemical reactions we have developed.