Proximal regioselectivity of the O,O′-dialkylation of tetrahydroxyketocalix[4]arene

Noa Seri, Silvio E. Biali*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The only dialkylated products obtained in the reaction of tetrahydroxyketocalixarene 2a with MeI/ K2CO3 or PhCH 2Br/K2CO3 are the corresponding proximal (i.e., 1,2) O,O′-dialkyl ethers, in contrast to the parent tetrahydroxycalix[4] arene 1a which affords the distal (1,3) dialkyl ether derivatives. Pairs of geminally alkylated phenoxy groups in the conformationally rigid dibenzylated and tetrabenzylated derivatives are oriented in an anti fashion. These results can be rationalized assuming that the 1,3-alternate arrangement of the rings preferred by 2a is adopted during all the intermediate stages of the alkylation. The NMR spectra (in CDCl3) of the monomethyl, dimethyl, trimethyl, and tetramethyl ether derivatives of 2a are in agreement with a 1,3-alternate conformation.

Original languageAmerican English
Pages (from-to)5278-5282
Number of pages5
JournalJournal of Organic Chemistry
Volume70
Issue number13
DOIs
StatePublished - 24 Jun 2005

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