A user-friendly and general mechanochemical method was developed to access rarely described NHC (N-heterocyclic carbene) silver(I) complexes featuring N,N-diarylimidazol(idin)ene ligands and non-coordinating tetrafluoroborate or hexafluorophosphate counter anions. Comparison with syntheses in solution clearly demonstrated the superiority of the ball-milling conditions.
[EN] PROCESS FOR PRODUCING CARBOXYLIC ACID ESTER<br/>[FR] PROCÉDÉ DE PRODUCTION D'UN ESTER D'ACIDE CARBOXYLIQUE
申请人:SUMITOMO CHEMICAL CO
公开号:WO2012176930A1
公开(公告)日:2012-12-27
An object of the present invention is to provide a new process which can produce a carboxylic acid ester from an aldehyde. The object is achieved by a process for producing a carboxylic acid ester, including the step of mixing a compound represented by the formula (2-1): (wherein R2 represents an alkyl group optionally having a substituent, or the like; R3 and R4 each represent independently an alkyl group optionally having a substituent, or the like, or R3 and R4 are taken together to form a divalent hydrocarbon group optionally having a substituent, or the like; Y represents a group represented by -S- or a group represented by -N(R5)-; R5 represents an alkyl group optionally having a substituent, or the like, or R5 is taken together with R4 to form a divalent hydrocarbon group optionally having a substituent; and X- represents an anion), a base, an alcohol, oxygen and an aldehyde to oxidize the aldehyde.
Herein we describe a NHC-catalyzed Truce–Smiles rearrangement of N-aryl methacrylamides which enables the cleavage of an inert aryl C–N bond. A range of trans-cinnamides could be obtained by the direct construction of a C(aryl)–C(alkenyl) bond and functional groups such as Br, Cl, CN, and pyridinyl are compatible with NHC catalysis. The reaction features high atom-economy, transition-metal free catalysis
derivatives with the C−H bonds of arenes have met with limited success. Herein, we report the rhodium‐catalyzed cross‐coupling of aryl carbamates with arenes bearing a convertible directing group. The key to success is the use of an in situ generated rhodium bis(N‐heterocyclic carbene) species as the catalyst, which can promote activation of the inert C(sp2)−O bond in aryl carbamates.