Partial functionalisation of C₄-symmetric tetramethoxyresorcinarenes

Abstract

Investigations into the distal-functionalisation of the phenols of racemic C 4symmetric tetramethoxyresorcinarene has led to a simple, single-step procedure that allows the isolation of gram quantities of partially silylated derivatives, with the targeted distally-silylated resorcinarene being obtained in a yield of 31%. These partially-silylated derivatives would serve as versatile intermediates for the selective functionalisation of this elegant architecture. The solid state structures of many of these derivatives have been determined by single crystal X-ray crystallography.

Synthesis of Distally‐Bridged Chiral Resorcinarene Crowns

“…Having synthesised gram quantities of the distal-TBDMS resorcinarene (1) in our previous work, [14] the crown ether bridge should be readily installed on the remaining two distal hydroxy groups of the resorcinarene. However, when resorcinarene (1) was subjected to the Cs 2 CO 3 /DMF bridging conditions employed by Nissinen and co-workers, [12a,12c] a complex mixture was produced.…”

“…Moreover, the NMR spectra matched that of the product that was obtained from the direct partially-selective benzylation of the starting tetramethoxyresorcinarene. [14] This deprotection reaction is scalable with a 3.9-gram reaction yielding the target product (4) in 97 %.…”

“…NMR data was consistent with literature. [14] General procedure for the synthesis of resorcinarene crowns: To a clear solution of resorcinarene (4) (1 equiv. ), caesium carbonate (8 equiv.)…”

“…No practical procedure has been known to enable the preparation of gram-quantities of a distally-functionalised tetramethoxyresorcinarene precursor, until our recent report. [14] Through this key precursor, we were then able to accomplish the first distally-bridged chiral tetramethoxyresorcinarene…”