Research On Carbenoid-involved Reactions Of Diazo Compounds Catalyzed By Hemin

Hemin,a natural iron porphyrin complex,widely exists in hemoproteins as a vital cofactor.In recent years,many hemin-containing enzymes have received considerable attention in biosynthetic and bioanalytic chemistry,such as myoglobin,horseradish peroxidase and cytochrome P450.While hemin itself is barely studied in organic synthesis,especially for unnatural organic reactions.Furthermore,metal carbenoids generated through the reactions between transition metal-catalysts and diazo compounds have attracted great attention for decades,which react with nucleophiles to achieve diverse transformations,such as X-H insertion(X= N,S,O,C,Si,B,ect.),cyclopropanation,and ylide formation.Under this background,we focus on expanding the catalytic repertoire of hemin in the unnatural carbene chemistry.The results include:Aqueous hemin-catalyzed,cyclodextrin-assisted insertion of carbenoids into N-H bonds:An aqueous hemin-catalyzed,cyclodextrin-assisted N-H insertion reaction of ?-diazo ester into aromatic amines is established.This aqueous catalytic system showed good compatibility with various aryl amines,with yields up to 96%.A size-controlled reaction phenomenon by different cyclodextrins was also observed when ethyl diazoacetate was used.Aqueous hemin-catalyzed sulfonium ylide formation and subsequent[2,3]-sigmatropic rearrangements:A mild hemin catalytic system for sulfonium ylide generation via metal carbenoid and subsequent[2,3]-sigmatropic rearrangement reaction in aqueous solvent is well-established,with the assistance of cyclodextrin and Triton X-100.The protocol displays high catalytic activity with a broad substrate scope of aryl/alkyl allyl sulfides and diazo reagents,affording homoallyl sulfide products in up to 99%yield.Hemin-catalyzed sulfonium ylide formation and subsequently reactant-controlled chemoselective rearrangements:Hemin-catalyzed competing routes of[1,2]-Stevens and Sommelet-Hauser rearrangements of benzyl sulfonium ylides through iron porphyrin carbenoid have been established.The rearrangements can be controlled by the electronic property of the substituents on the benzyl group together with solvent effects.Electron-donating or weak electron-withdrawing groups lead to the[1,2]-Stevens rearrangement,whereas strong electron-withdrawing groups at para-position favor the latter pathway under aqueous conditions.