Rhodium(II)-catalyzed multicomponent assembly of α,α,α-trisubstituted esters via formal insertion of O–C(sp3)–C(sp2) into C–C bonds

Abstract

The direct cleavage of C(CO)−C single bonds, delivering otherwise inaccessible compounds, is a significant challenge. Although the transition metal-catalyzed insertion of functional groups into C(CO)−C bonds has been studied, strained ketone substrates or chelating assistance were commonly required. In this article, we describe a rhodium(II)-catalyzed three-component reaction of 1,3-diones, diazoesters, and N,N -dimethylformamide (DMF), leading to an unusual formal insertion of O–C(sp 3 )–C(sp 2 ) into unstrained C(CO)−C bonds. This procedure provides a rapid entry to a gamut of otherwise inaccessible α,α,α-trisubstituted esters/amide from relatively simple substrates in a straightforward manner. 55 examples of highly decorated products demonstrate the broad functional group tolerance and substrate scope. The combination of control experiments and isotope-labeling reactions support that O, C(sp 3 ), and C(sp 2 ) units derive from 1,3-diones, diazoesters, and DMF, respectively.

Novel oxoisochromene synthesisviachemoselective O–H insertion of 1,3-dicarbonyl compounds and subsequent Pd-catalyzed intramolecular arylation reaction

“…On the other hand, 1,3-dicarbonyl compounds are versatile substrates for organic synthesis, in particular, C–H, 10 C–C 11 and O–H 12 insertion reactions (Fig. 1).…”

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

“…40,41 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 1c). 42 These two extremely rare examples successfully realized the insertion of diazoes into acyclic C−C bonds, but the range of substrates were limited to 1,3-dicarbonyl species. Moreover, to the best of our knowledge, the insertion of diazo-derived metal-carbene into C(sp)− C(sp 3 ) bonds of internal alkynes is still unknown.…”

“…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) . These two extremely rare examples successfully realized the insertion of diazoes into acyclic C–C bonds, but the range of substrates were limited to 1,3-dicarbonyl species.…”

A Selective C–C Bond Cleavage Strategy Promoted by Visible Light

“…The same selectivity is also observed for the use of other metal catalysts, such as Sc­(OTf) 3 or CuCN/PCy 3 /NaBAr 3 , or a heterogeneous catalyst containing a Brønsted acid source, TFMSA@BSA-15 . However, the same reagents, 1 and 2 , have been reported to selectively lead to formal C–C insertion compounds 4 in the presence of the catalyst AgOTf ,, or in the presence of the same previously reported gold catalyst (ArO) 3 PAuNTf 2 (Ar = 2,4- t Bu 2 C 6 H 3 ) while also in the presence of a catalytic amount of H 3 PO 4 and by carefully fine-tuning the reactivity of the system by choosing the ester moiety of the aryldiazoacetate partner 1 as the group (2,6-Cl 2 )­C 6 H 3 (Scheme a) …”

“…6 However, the same reagents, 1 and 2, have been reported to selectively lead to formal C−C insertion compounds 4 in the presence of the catalyst AgOTf 4a, 7,8 or in the presence of the same previously reported gold catalyst (ArO) 3 PAuNTf 2 (Ar = 2,4-t Bu 2 C 6 H 3 ) while also in the presence of a catalytic amount of H 3 PO 4 and by carefully fine-tuning the reactivity of the system by choosing the ester moiety of the aryldiazoacetate partner 1 as the group (2,6-Cl 2 )C 6 H 3 9 (Scheme 1a). 10 In contrast to these strategies, the construction of organic molecules is also possible via the cleavage of C−C bonds promoted by (high-energy) UV light. Norrish reactions are possibly among the most well-known textbook strategies, albeit they generally afford only poor or modest selectivities 11 (Scheme 1b).…”