Resolution of inherently chiral calix[4]arenes with AABB and CDCD substitution patterns on the upper and lower rims, respectively

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• 作者：Caccamese ; Salvatore ; Bottino ; Alessandra ; Cunsolo ; Francesca ; Parlato ; Silvia ; Neri ; Placido
• 刊名：Tetrahedron: Asymmetry
• 出版年：2000
• 出版时间：August 11, 2000
• 年：2000
• 卷：11
• 期：15
• 页码：3103-3112
• 全文大小：220 K

文摘

Proximal di-tert-butylcalix[4]arene (5,11-di-tert-butylcalix[4]arene-25,26,27,28-tetrol) 1b, obtained by direct partial removal of tert-butyl groups from p-tert-butylcalix[4]arene, gave high yields of inherently chiral derivatives upon ‘symmetry breaking’ by syn-distal di-O-alkylation or di-O-acylation in the presence of K₂CO₃. The chirality of these compounds was proven by the splitting of ¹H NMR signals in the presence of Pirkle's reagent and in some cases by HPLC enantiomeric resolution using chiral stationary phases and corroborated by mirror-image CD spectra.