TY - JOUR AU - Koppenwallner, Maximilian; Rais, Eduard; Uzarewicz-Baig, Magdalena; Tabassum, Sobia; Gilani, Mazhar Amjad; Wilhelm, René TI - Synthesis of New Camphor-Based Carbene Ligands and Their Application in a Copper-Catalyzed Michael Addition with B2Pin2 SN - 0039-7881 SN - 1437-210X PY - 2015 JO - Synthesis JF - Synthesis LA - EN VL - 47 IS - 06 SP - 789 EP - 800 ET - 2014/12/22 DA - 2015/02/25 KW - N-heterocyclic carbenes KW - copper KW - catalysis KW - Michael addition KW - camphor AB - In this work the synthesis of new asymmetric camphor-based carbene ligands from camphoric acid is described. The new carbenes can be prepared directly in high yields by the sequence: regioselective arylation of the less hindered primary amine group of (+)-cis-1,2,2-trimethylcyclopentane-1,3-diamine by Buchwald–Hartwig amination, treatment with trimethyl orthoformate, and finally treatment with a benzylic halide. The resulting carbenes, incorporating an aryl and a benzylic substituent, were successfully applied as ligands in a copper-catalyzed B2Pin2 [bis(pinacolato)diboron] addition to an unsaturated carbonyl compound. Depending on the substituents dual stereocontrol was observed and one enantiomer was obtained in up to 82% ee and the opposite enantiomer in up to 78% ee. PB - © Georg Thieme Verlag DO - 10.1055/s-0034-1379877 UR - http://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0034-1379877 ER -