Enantioselective synthesis of tripodal cyclophanes and pyridinophanes by intramolecular [2+2+2] cycloaddition
摘要:
An enantioselective intramolecular [2+2+2] cycloaddition of 2-aminophenol-tethered triynes and diyne-nitriles proceeded using the chiral Rh catalysts, and tripodal cyclophanes and pyridinophanes with a long ansa chain (up to [16]pyridinophane) were obtained in acceptable yield with high to almost perfect ee. In the reaction of triynes, we elucidated that the oxygen atom at the alkyne terminus is essential for the excellent enantioselectivity. For the construction of cage-type molecule, the choice of rigid tether, which connects 1,6-diyne moiety with a side carbon chain having alkyne or cyano group on its terminus, was important, and 8-amino-2-naphthol moiety was also a preferable tether. (C) 2012 Elsevier Ltd. All rights reserved.
Enantioselective Synthesis of Chiral Tripodal Cage Compounds by [2 + 2 + 2] Cycloaddition of Branched Triynes
作者:Takanori Shibata、Toshifumi Uchiyama、Kohei Endo
DOI:10.1021/ol9014893
日期:2009.9.3
Cyclotrimerization of triynes branched by a nitrogen atom of 2-aminophenol yielded planar-chiral tripodal cagecompounds. When a cationic Rh−Me-DUPHOS catalyst was used, the cycloadducts were obtained in high yield and excellent ee, and a macrocyclic compound with a [15]cyclophane system was also obtained. This method can be further applied to the synthesis of a triarmed pyridinophane by the intramolecular
Enantioselective synthesis of tripodal cyclophanes and pyridinophanes by intramolecular [2+2+2] cycloaddition
作者:Takanori Shibata、Mayu Miyoshi、Toshifumi Uchiyama、Kohei Endo、Nobuaki Miura、Kenji Monde
DOI:10.1016/j.tet.2012.01.046
日期:2012.3
An enantioselective intramolecular [2+2+2] cycloaddition of 2-aminophenol-tethered triynes and diyne-nitriles proceeded using the chiral Rh catalysts, and tripodal cyclophanes and pyridinophanes with a long ansa chain (up to [16]pyridinophane) were obtained in acceptable yield with high to almost perfect ee. In the reaction of triynes, we elucidated that the oxygen atom at the alkyne terminus is essential for the excellent enantioselectivity. For the construction of cage-type molecule, the choice of rigid tether, which connects 1,6-diyne moiety with a side carbon chain having alkyne or cyano group on its terminus, was important, and 8-amino-2-naphthol moiety was also a preferable tether. (C) 2012 Elsevier Ltd. All rights reserved.