ISSN:
0009-2940
Keywords:
[1n]Metabiphenylophanes
;
Calixarenes
;
Spherands
;
Diastereoselectivity
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Condensation of 5,5′-di-tert-butyl-2,2′-dihydroxybiphenyl (1) with formaldehyde yields a cyclic trimer 2 (and tetramer 3) having three (four) methylene groups less than a calix[6]-arene (calix[8]arene). Alkylation of the (flexible) trimer with ethyl bromoacetate gives exclusively the stereoisomer 4 with C2 symmetry, while the isomer with D3 symmetry is not observed. Two isomers 6a and 6b (C2 and C1 symmetry) are obtained by treatment with tert-butyl bromoacetate which both are converted by transesterification with methanol into the same hexamethyl ester 5 having C2 symmetry. These results are rationalized by restricted rotation around Ar—Ar bonds for larger O-alkyl groups also around Ar—CH2—Ar bonds. The structure of the hexaethyl ester 4 is also confirmed by single crystal X-ray analysis.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941270219
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