Lower cyclic oligomers C-2-C-5 of a family of naphthalenophane formaldehyde acetals C-n have been isolated and characterized, the dimer being obtained in two atropisomeric forms, syn-C-2 and anti-C-2, as confirmed by X-ray analysis. The investigated cyclophanes showed interesting recognition properties towards electron-poor guests (K approximate to 10(5) M-1 for association of the guanidinium ion with C-3 in chloroform). A library of macrocycles was generated by acid catalyzed transacetalation of C-n in chloroform, but the dynamic nature of the system was spoiled by the occurrence of irreversible reaction pathways promoted by the relatively easy formation of extended benzyl-like carbocations I. (C) 2013 Elsevier Ltd. All rights reserved.
Naphthalenophane formaldehyde acetals as candidate structures for the generation of dynamic libraries via transacetalation processes / Albert, Ruggi; Roberta, Cacciapaglia; DI STEFANO, Stefano; Bodo, Enrico; Franco, Ugozzoli. - In: TETRAHEDRON. - ISSN 0040-4020. - STAMPA. - 69:13(2013), pp. 2767-2774. [10.1016/j.tet.2013.01.080]
Naphthalenophane formaldehyde acetals as candidate structures for the generation of dynamic libraries via transacetalation processes
DI STEFANO, Stefano;BODO, Enrico;
2013
Abstract
Lower cyclic oligomers C-2-C-5 of a family of naphthalenophane formaldehyde acetals C-n have been isolated and characterized, the dimer being obtained in two atropisomeric forms, syn-C-2 and anti-C-2, as confirmed by X-ray analysis. The investigated cyclophanes showed interesting recognition properties towards electron-poor guests (K approximate to 10(5) M-1 for association of the guanidinium ion with C-3 in chloroform). A library of macrocycles was generated by acid catalyzed transacetalation of C-n in chloroform, but the dynamic nature of the system was spoiled by the occurrence of irreversible reaction pathways promoted by the relatively easy formation of extended benzyl-like carbocations I. (C) 2013 Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
