Rh(Ⅲ) Catalyzed Diazo-1,3-cyclohexanedione Synthesis Of Isocoumarins And Octahydrobenzoxanthene Derivatives

Oxygenated heterocyclic compounds exist widely in many complex natural product molecules and drug molecules.They have good biological activity and pharmacological activity.They have been widely used in medicine,materials and probes.Therefore,the development of green,efficient and accurate methods for synthesizing oxygen-containing heterocyclic compounds has always been a direction for synthetic chemists.Diazonium compounds can form carbene in the presence of transition metals,and can realize multiple chemical reactions with many reagents.Therefore,they have an important position in organic synthesis and drug synthesis.In this paper,we reviewed the recent studies on the organic reactions involving diazo compounds in recent years,and developed a stable diazo-1,3-ring based on the study of diazo-1,3-dione catalyzed by ruthenium in the earlier part of our research group.The methodological study on the synthesis of oxygen-containing heterocyclic compounds from hexanedione catalyzed by Rh（Ⅲ）and transition metals,with the guide group compounds,is as followsA methodological study on the synthesis of isocoumarin compounds catalysedby[Cp*RhCl₂]₂wasdevelopedforthereactionof2-diazo-1,3-cyclohexanedione,phthalic anhydride and methanol.The reaction was activated by C-H bond and the intramolecular esterification reaction forms an isocoumarin compound.The reaction conditions are mild and the yield is high.The reaction removes H₂O and releases N₂ in green synthesis.Based on the literature and experimental results,the reaction mechanism of this reaction was proposed.Developmentofmethodologyforthesynthesisof octahydrobenzoxanthenesusingdiazo-1,3-cyclohexanedione,benzoylacetonitrile and toluene in the presence of trivalent europium[Cp*RhCl₂]₂ and Cs OAc the study.The first occurrence of C-H bond activation forms the C-C bond between the molecules,and the endotherm undergoes an intramolecular cyclization reaction to form a new C-O bond.The reaction mechanism of this reaction was proposed based on literature and experiments.This step gives five rings of octahydrobenzoxanthenes with great significance.