Studies Of Semipinacol Rearrangement

The multi-functional unit with quaternary carbon extensively exists in biologically significant natural products and other important organic molecules,and it is of major importance to stereoselectively construct this unit in organic chemistry.The semipinacol rearrangement is becoming a widely applied reaction in organic synthesis allowing the stereoselective construction of these units.Some significant progresses have been made by our group on this field.This thesis finished some breakthroughs in the high efficient and enantioselective construction of multi-functional unit with quaternary carbon and correspondingly a series of progressive results were achieved in this research field.The following two parts are mainly included:1.Tandem aziridination/rearrangement reaction of allylic alcohols induced by silica gel.On the basis of this methodology,an efficient and highly stereoselective approach to various 2-quaternary Mannich bases have been put in place from simple allylic alcohols in high yield,overcoming the limit of low yield of aziridination on the previous method.This kind of[1,2]-rearrangement process was firstly realized by silica gel,and expanded the research field of the tandem semipinacol rearrangement of aziridino alcohols.2.Enantioselective semipinacol rearrangement catalyzed by organocatalyst.The semipinacol rearrangement and fast developing concept of organocatalyst in last decade were combined successively,achieving asymmetric semipinacol rearrangement catalyzed by organocatalyst.Multi-functional spiro-quaternary centers were synthesized in up to 97%ee by this new method.A new and attractive research field with a good prospect of development and utilization was exploited on semipinacol rearrangement.