Synthesis of new heterofunctionalized resorcinarene derivatives

Abstract

New derivatives of heterofunctionalized resorcinarenes differing by the nature, number, ratio, and orientation of functional groups were obtained by modification of free reactive centers in the phosphoresorcinarenes of different types.Currently great attention is paid to the design of the receptor systems that can act as chemosensors or extractants. The most common matrices for their creation are macrocyclic molecules containing free cavities and a large number of reaction centers located in a certain mode relative to each other [1][2][3][4]. These compounds include resorcinarenes and their modified analogs. Due to the conformational lability of these molecules and presence of hydroxy groups and the ortho position of benzene rings at the macrocycle whose reactivity can be controlled, the resorcinarenes form a convenient basis for the design of complex compounds with polyfunctionalized cavity systems [5-10].Our goal was to synthesize derivatives of the new heterofunctional resorcinarenes and consider the ways to modify the free reaction sites of phosphoresorcinolarenes of various types.To implement this task we used a common scheme: the resorcinarenes were phosphorylated with phosphorous amides, the phospho(IV)resorcinarenes formed were transformed in the phosphorus(IV) resorcinollarenes, and various functional groups were introduced into the latter molecules.Depending on the required regioselectivity of the process, we selected as the basic compounds the resorcinollarenes I with certain substituents in methylidene bridges and ortho position of benzene rings of the macro-cyclic framework.As a platform for the synthesis of new orthofunctionalized phosphocavitands served ortho-bromotetra(phenylethyl)resorcinarene Ia, due to its boat conformation, that is convenient for the phosphocyclization [9,11], and to the presence of easily replaceable bromine atoms in the ortho positions of benzene rings of the macrocyclic skeleton [12][13][14][15] (Scheme 1).The cyclophosphorylation of Ia with tripiperidylphosphite was performed by the standard method [16,17] in dioxane at room temperature. To the formed phosphorus(III)cavitand was added sulfur without its isolation from the reaction mixture (Scheme 1). Two singlet signals with equal integral intensities appeared in the 31 P NMR spectrum of the isolated tionamidophosphatocavitand II and the doubling of signals of the the benzene rings meta-protons of the framework in the 1 H NMR spectrum indicated the implementation of the kite conformation [17,18].The phosphorus(IV)cavitand II was brpoght into the reaction of electrophilic substitution. Compound II was treated with BuLi, then to it was added either methylchloroformate, which led to ortho-methoxycarbonyl derivative III (Scheme 1, a), or sequentially trimethylborate and hydrogen peroxide with sodium hydroxide solution, which completed by the formation of the ortho-hydroxylated cavitands IV (Scheme 1, b). Further, in the interaction of IV with acetic anhydride ortho-acetylated cavitand V was obtained (Scheme 1, c).Compounds III...