Uncommon carbene insertion reactions

Abstract

Transition-metal-catalysed carbene insertion reaction is a straightforward and efficient protocol for the construction of carbon–carbon or carbon–heteroatom bonds.

Fe-Catalyzed Selective Formal Insertion of Diazo Compounds into C(sp)–C(sp3) Bonds of Propargyl Alcohols: Access to Alkyne-Substituted All-Carbon Quaternary Centers

“…31 Notably, transition metals with diazo compounds are able to form energetic carbenoids that can formally insert into the C−C bonds, producing homologues plus one carbon. 32 This one-carbon insertion strategy not only allows selective cleavage of inert C−C bonds but also forms functionally all-carbon quaternary centers. 33,34 However, the strained system is commonly required as it can provide a pivotal thermodynamic driving force through strain release.…”

“…In these transformations, acid or base can promote homologation of diazo compounds with ketones, which insert into C–C bonds through a carbene-free process . Notably, transition metals with diazo compounds are able to form energetic carbenoids that can formally insert into the C–C bonds, producing homologues plus one carbon . This one-carbon insertion strategy not only allows selective cleavage of inert C–C bonds but also forms functionally all-carbon quaternary centers. , However, the strained system is commonly required as it can provide a pivotal thermodynamic driving force through strain release. − In 2018, Bi and co-workers reported the first Ag-catalyzed one-carbon insertion into the unstrained C­(CO)–C bonds of 1,3-dicarbonyl compounds using diazoes (the left of Figure c). , Subsequently, Cheng’s group developed an unparalleled Rh-catalyzed multicomponent assembly reaction of 1,3-diones, diazoesters, and N , N -dimethylformamide via insertion of O –C­(sp 3 )–C­(sp 2 ) into unstrained C­(CO)–C bonds (the right of Figure c) .…”

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C−H Functionalization and Allylic Alkylation

“…[10][11][12][13][14] Various metal-carbenoid intermediates have found wide applications in synthetic chemistry due to their unique reactivities. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] In this regard, the aromatic C(sp 2 )À H functionalization of electron-rich aromatics with metal carbenes generated from diazo compounds has attracted considerable attention, and transition metal catalysts based on Rh, [33][34][35][36][37][38][39][40][41][42][43][44] Au, [45][46][47][48][49][50][51][52][53][54][55] Cu, [56][57]…”

Electrochemical S–H and O–H insertion reactions from thiols or salicylic acids with diazo esters

“…Diazo compounds are important starting materials that are used widely in the organic synthesis field, 1 including X–H insertion (X = C, 2 N, 3 O, 4 S, 5 Si, 6 B, 7 etc. ), C–C coupling, 8 alkene cyclization 9 and the Wolff rearrangement.…”