Chiral photochemistry in a confined space: torquoselective photoelectrocyclization of pyridones within an achiral hydrophobic capsule

TETRAHEDRON

卷:65

Article

Sundaresan, Arun Kumar¹  Gibb, Corinne L. D.²  Gibb, Bruce C.²  Ramamurthy, V.¹ 

[1] Univ Miami, Dept Chem, Coral Gables, FL 33124 USA

[2] Univ New Orleans, Dept Chem, New Orleans, LA 70148 USA

关键词: Host-guest;    Chiral photochemistry;    Electrocyclization;    Pyridones;    Confined space;    Supramolecular assemblies;   

DOI  :  10.1016/j.tet.2009.01.110

来源: Elsevier

【 摘 要 】

Chiral induction during the photoelectrocyclization of pyridones included within octa acid (C)A) capsule has been established. Chiral induction is brought about by a chiral auxiliary appended to the reactive pyridone moiety. Importantly, the same chiral auxiliary while ineffective in acetonitrile solution is found to be effective within the confined space of OA capsule. The diastereomeric excess of 92% obtained here is comparable only to that in solid state. OA capsule, we believe, provides restriction to the rotational motions of the reactant pyridone and chiral auxiliary and thus places the chiral auxiliary in a selective conformation with respect to the reactive pyridone part. A correlation between the position of the methyl group on the pyridone ring and diastereoselectivity was noted. Structures of the host-guest complexes were examined by H-1 NMR and the data were used to obtain preliminary information concerning the mechanism of chiral induction within the confined spaces of OA capsule. (C) 2009 Elsevier Ltd. All rights reserved.

【 授权许可】

Free