Based on isolobal analogy,the definition of metallafuran was described and its synthetic chemistry was briefly summarized.In the structure of furan,when one of CH groups was replaced by an isolobal metal fragment ML n(M=metal;L=ligand),the corresponding organometallic complex was called metallafuran,which should be two possible isomers called a-metallafuran(metal fragment at a-carbon of original furan)and b-metallafuran(metal fragment at b-carbon of original furan).As an organometallic complex,a-metallafuran has two resonant forms:one can be viewed as carbonyl coordinated vinyl metal complex and the other can be viewed as alkoxymetal carbene.Therefore,a-metallafuran was also called chelated vinyl ketone metal complex or oxametallacyclopentadiene in the early literatures.For synthesis of metallafurans,a-metallafurans were very common and easily prepared,for example,from alkynes insertion into acyl metal complexes and so on.While there were rare examples reported for b-metallafurans.In this mini review,the synthetic chemistry of metallafuran was mainly focused on its formation mechanism.
This review summarizes the recent advances in the catalytic syntheses of CFS-containing organic molecules using various nucleophilic or electrophilic trifluoromethylthiolating reagents.C-halogen and C—H bonds in various molecules have been transformed to C—SCFbonds by transition-metal-catalyzed reactions,such as cross-coupling of aryl halides.Enantioselective reactions controlled by chiral metal complexes or chiral organocatalysts have afforded many trifluoromethylthiolated chiral architectures,such as β-ketoesters and oxindoles.Very recently,visible-light-induced photoredox trifluoromethylthiolations have been developed,providing versatile CFS-containing structures efficiently.
An improved method for the preparation of pentafluoroethylating reagent pentafluoroethyl-substituted benzio- doxole （BIX-C2Fs） was described. Under mild conditions, BIX-C2F5 was able to react with β-ketoesters or aryl/ heteroaryl boronic acids to generate pentafluoroethylated compounds in good yields.
An effective method for Pd-catalyzed cross-coupling between polyfluoroarenes and cyclic vinyl triflates has been developed.This protocol provides a useful and facile access to polyfluoroarylated cyclic alkenes that are difficult to prepare otherwise.The advantages of this method are its high efficiency and operational simplicity.
