Exploiting the Chiral Ligands of Bis(imidazolinyl)- and Bis(oxazolinyl)thiophenes—Synthesis and Application in Cu-Catalyzed Friedel–Crafts Asymmetric Alkylation
作者:Mohammad Shahidul Islam、Abdullah Saleh Alammari、Assem Barakat、Saeed Alshahrani、Matti Haukka、Abdullah Mohammed Al-Majid
DOI:10.3390/molecules26237408
日期:——
Five new C2-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The utility of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subsequently, the optimized tridentate
2,5-双(咪唑啉基)噻吩(L1 – L3)和2,5-双(恶唑啉基)噻吩(L4和L5)的五个新的C 2 -对称手性配体由噻吩-2,5-二羧酸合成(1 ) 与具有优异光学纯度和化学产率的对映纯氨基醇 ( 4a – c )。探索了这些新手性配体在 Friedel-Crafts 不对称烷基化中的应用。随后,优化的三齿配体L5和 Cu(OTf) 2催化剂(15 mol%)在甲苯中放置 48 小时,以中等至良好的产率(高达 76%)和良好的对映选择性(高达 81% ee)促进了 Friedel-Crafts 不对称烷基化。的双(恶唑啉基)噻吩配体的比更有效的双(咪唑啉基)为弗里德尔-克拉夫茨不对称烷基化的不对称诱导噻吩类似物。