Enantioselective Synthesis of Distorted π‐Extended Chiral Triptycenes Consisting of Three Distinct Aromatic Rings by Rhodium‐Catalyzed [2+2+2] Cycloaddition. Issue 14 (30th January 2020)

• Record Type: Journal Article
• Authors: Aida, Yukimasa; Shibata, Yu; Tanaka, Ken
• Is Part Of: Chemistry. Volume 26:Issue 14(2020)
• Page Start: 3004
• Page End: 3009
• Publication Date: 2020-01-30
• Subjects: [2+2+2] cycloaddition -- chiral triptycenes -- cyclic alkenes -- enantioselective synthesis -- rhodium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201905519
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The enantioselective synthesis of distorted π‐extended chiral triptycenes, consisting of three distinct aromatic rings, has been achieved with high ee value of 87 % by the cationic rhodium(I)/segphos complex‐catalyzed enantioselective [2+2+2] cycloaddition of 2, 2′‐di(prop‐1‐yn‐1‐yl)‐5, 5′‐bis(trifluoromethyl)‐1, 1′‐biphenyl with 6‐methoxy‐1, 2‐dihydronaphthalene followed by the diastereoselective Diels–Alder reaction and aromatization. Demethoxy derivatives were also synthesized by the C−O bond cleavage. In this synthesis, the use of the electron‐deficient diyne and the electron‐rich alkene is crucial to suppress the undesired strain‐relieving carbocation rearrangement and stabilize the distorted triptycene structure. Abstract : The enantioselective synthesis of distorted π‐extended chiral triptycenes, consisting of three distinct aromatic rings, has been achieved with high ee value of 87 % by the rhodium(I)‐catalyzed [2+2+2] cycloaddition followed by the Diels–Alder reaction and aromatization. Demethoxy derivatives were also synthesized by the C−O bond cleavage. In this synthesis, the use of an electron‐deficient diyne and an electron‐rich alkene is crucial to suppress the undesired strain‐relieving carbocation rearrangement and stabilize the distorted triptycene structure (see figure).