Free Radical-promoted Cycloalkanol Ring-opening Reactions And Heteroaryl Migration Reactions

Remote functionalized alkyl ketone compounds are widely present as ubiquitous structural motif in natural products,drugs,and biologically active molecules.The carbonyl distal functionalization product can be rapidly synthesized through the ring-opening reaction of the cycloalkanol and the tertiary alcohol migration reaction.Therefore,I mainly use the free radical-promoted cycloalkanol ring-opening reactions and heteroaryl migration reactions to engage in the synthesis of these compounds during the master’s degree.(1)Manganese-catalyzed ring-opening hydrazinationWe introduce manganese-catalyzed ring-opening hydrazination.In the presence of Mn(OAc)3.2H2 O,cyclobutanol is oxidized by single electron to form alkoxy radicals,which are selectively cleaved by C-C bonds to form alkyl radicals,the alkyl radicals are captured by DBAD,and efficiently produced γ-substituted alkyl hydrazines,the ring-opening under mild reaction conditions,the functional groups are well compatible and exclusive regioselectivities.(2)Visible-light catalyzed ring-opening bromination of unstrained cycloalkanolsDue to the ring-strain energy is small and the carbocyclic ring is more stable,the ring-opening reaction of unstrained cycloalkanols is more challenging..In this part,we mainly introduce the visible-light catalyzed ring-opening bromination of unstrained cycloalkanols.We use cyclopentanol as a substrate,PIDA as oxidant and NBS as bromine source,under visible-light irradiation,successfully constructed the ring-opening bromination,This reaction is applicable not only to the ring-opening bromination of cyclopentanols,but also to the ring-opening bromination of cyclohexanols,cycloheptanols,cyclododecanols,and cyclopentadecanols.This method can be constructed a distally brominated alkyl ketones that is difficult to obtain by the conventional methods.(3)Visible-light catalyzed di/monofluoroalkyl heteroarylation of unactivated alkenesWe descride visible-light catalyzed di/monofluoroalkyl heteroarylation of unactivated alkenes.We used benzothiazole-substituted tertiary alcohol as a substrate,various fluorine-containing alkylation reagents such as Br CF2 COOEt are used as fluorine reagents.Under visible-light irradiation,di/monofluoroalkyl heteroarylation of unactivated alkenes is rapidly achieved by the 1,4-heteroaryl migration reaction.