Asahara Chizuru, Iwamoto Takuya, Akashi Mitsuru, Shigemitsu Hajime, Kida Toshiyuki
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, 565-0871, Japan.
Chempluschem. 2018 Sep;83(9):868-873. doi: 10.1002/cplu.201800348.
A 6-O-tert-butyldimethylsilylated β-cyclodextrin (TBDMS-β-CD) dimer, in which two TBDMS-β-CD rings are connected in a head-to-head fashion by a m-xylylene linker, effectively forms inclusion complexes with pyrene and naphthalene in nonpolar organic solvents such as cyclohexane and benzene. This TBDMS-β-CD dimer shows a higher inclusion ability toward these guests than a TBDMS-β-CD dimer bearing a p-xylylene linker due to the greater cooperation of the two TBDMS-β-CD rings for the guest inclusion. Unlike the corresponding monomer, the TBDMS-β-CD dimer bearing a m-xylylene linker is also a good host even in polar organic solvents such as tetrahydrofuran. High chiral recognition of aromatic amines and alcohol is realized by utilizing inclusion within the cavity of the TBDMS-β-CD dimer in cyclohexane. In particular, an extremely high binding selectivity for (S)-1-(1-naphthyl)ethylamine and (S)-1-(1-naphthyl)ethanol over the corresponding (R)-isomers is achieved. Moreover, by utilizing the high chiral recognition with the TBDMS-β-CD dimer in cyclohexane, a non-enzymatic kinetic resolution of racemic 1-(1-naphthyl)ethylamine via enantioselective N-benzoylation is attained with an enantiomer excess of up to 87 % and an s-factor of 15.
一种6-O-叔丁基二甲基硅烷基化的β-环糊精（TBDMS-β-CD）二聚体，其中两个TBDMS-β-CD环通过间二甲苯连接基以头对头的方式相连，在环己烷和苯等非极性有机溶剂中能有效地与芘和萘形成包合物。由于两个TBDMS-β-CD环在客体包合方面具有更大的协同作用，这种TBDMS-β-CD二聚体对这些客体的包合能力比带有对二甲苯连接基的TBDMS-β-CD二聚体更高。与相应的单体不同，带有间二甲苯连接基的TBDMS-β-CD二聚体即使在四氢呋喃等极性有机溶剂中也是一种良好的主体。通过在环己烷中利用TBDMS-β-CD二聚体腔内的包合作用，实现了对芳香胺和醇的高手性识别。特别是，对于（S）-1-（1-萘基）乙胺和（S）-1-（1-萘基）乙醇，相对于相应的（R）-异构体，实现了极高的结合选择性。此外，通过在环己烷中利用TBDMS-β-CD二聚体的高手性识别，通过对映选择性N-苯甲酰化实现了外消旋1-（1-萘基）乙胺的非酶动力学拆分，对映体过量高达87%，s-因子为15。
