Efficient resolution of racemic crown-shaped cyclotriveratrylene derivatives and isolation and characterization of the intermediate saddle isomer

• Sven Götz,
• Andreas Schneider and
• Arne Lützen

Beilstein J. Org. Chem. 2019, 15, 1339–1346, doi:10.3762/bjoc.15.133

• ; cyclotriveratrylenes; HPLC; macrocycles; racemization; saddle isomer; Introduction Cyclotriveratrylenes (CTVs) [1][2][3][4][5][6][7][8] are cyclic bowl-shaped molecules and belong to the most studied concave host molecules in supramolecular chemistry besides, e.g., calixarenes and resorcinarenes [9], cyclodextrins

• stable saddle conformers. A first example of such a saddle isomer of an achiral hexamethoxy-substituted CTV could be isolated and described by Luz and co-workers in 2004 [26]. At that time, they achieved this by heating the crown form to high temperatures and subsequent rapid cooling of the mixture

• the intermediate saddle conformer. Results and Discussion Synthesis and chiral resolution of 1 and isolation of the saddle isomer The synthesis of (rac)-1 was accomplished according to the already mentioned protocol by Rousseau and co-workers (Scheme 3) [60] although it should be noted here that