Details

Autor(en) / Beteiligte

• Serrano, Elena
• Juan, Alberto
• García-Montero, Angel
• Soler, Tatiana
• Jiménez-Márquez, Francisco
• Cativiela, Carlos
• Gomez, M. Victoria
• Urriolabeitia, Esteban P.

Titel

Stereoselective Synthesis of 1,3-Diaminotruxillic Acid Derivatives: An Advantageous Combination of CH-ortho-Palladation and On-Flow [2+2]-Photocycloaddition in Microreactors

Ist Teil von

• Chemistry : a European journal, 2016-01, Vol.22 (1), p.144-152

Ort / Verlag

Weinheim: WILEY-VCH Verlag

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• The stereoselective synthesis of ε‐isomers of dimethyl esters of 1,3‐diaminotruxillic acid in three steps is reported. The first step is the ortho‐palladation of (Z)‐2‐aryl‐4‐aryliden‐5(4H)‐oxazolones 1 to give dinuclear complexes 2 with bridging carboxylates. The reaction occurs through regioselective activation of the ortho‐CH bond of the 4‐arylidene ring in carboxylic acids. The second step is the [2+2]‐photocycloaddition of the CC exocyclic bonds of the oxazolone skeleton in 2 to afford the corresponding dinuclear ortho‐palladated cyclobutanes 3. This key step was performed very efficiently by using LED light sources with different wavelengths (465, 525 or 625 nm) in flow microreactors. The final step involved the depalladation of 3 by hydrogenation in methanol to afford the ε‐1,3‐diaminotruxillic acid derivatives as single isomers. An advantageous combination: The stereoselective synthesis of ε‐isomers of dimethyl esters of 1,3‐diaminotruxillic acid is easily achieved in three steps (see scheme): 1) regioselective CH‐ortho‐palladation of (Z)‐2‐aryl‐4‐aryliden‐5(4H)‐oxazolones; 2) efficient [2+2]‐photocycloaddition of the CC exocyclic bonds using LED light sources of different wavelengths in continuous flow microreactors; and 3) depalladation by hydrogenation in methanol.