Novel Spherand‐Type Calixarenes – Synthesis, Conformational Studies, and Isomer Separation

Abstract

The novel macrocyclic compounds hexahydroxy[1.0.1.0.1.0]-spectra. Methylation of the hydroxyl groups of 6b and 6c with 6b and octahydroxy[l.0.l.0.l.0.l.O]metacyclophane 6c have Me1 gives the corresponding methoxy[l,]metabiphenylobeen prepared in 50-70% yield by base-catalyzed conden-phanes 7b and 7c in good yields. The metacyclophane 7 b has sation of 5,5'-di-tert-butyl-2,2'-dihydroxybiphenyl (5) with been found to consist of two isomers, out of which one was formaldehyde in xylene. The conformations of trimer 6b and separated pure. The structural characterization of these prodtetramer 6c have been evaluated from their dynamic 'H-NMR ucts is discussed.Due to their importance in supramolecular chemistry['] a large variety of macrocyclic compounds such as crown ethersL2], cryptatesF3], cyclophane~~~~, and spherandsF5I have been synthesized and their properties investigated. Our present work is directly related to the studies of Cram and his co-workersF5] in designing spherands possessing 1,l'-biarene units (e. g. 1) which contain enforced, spherical cavities lined with electron pairs of heteroatoms so that upon complexation with metal ions no conformational rearrangement is possible.Closely related to the spherands are the "calixarenes", [l,]metacyclophanes (example 2a), prepared by base-catalyzed condensation of p-substituted phenols with formaldehyde[6a1. These are attractive building blocks, their phenolic hydroxyl groups being ordered in well-shaped cyclic arraysF6] which can be f~nctionalized~'~ to give novel guest inclusion blocks. The combination of structural elements of both spherands and calixarenes is expected to lead to novel macrocyclic compounds, which may be highly stimulating for future work in the field of host-guest chemistry.Recently, we have demonstrated a convenient synthesis of the propane-bridged calixareneanalogs of metacyclophanes such as tetrahydroxy (83%) 5 We describe in this paper the first example of the synthesis of a series of hydroxy[l,]metabiphenylophanes with three and four biarene units, 6, and their methoxy derivatives 7, derived from 5,5'-di-tert-butyl-2,2'-dihydroxybiphenyl (5). These compounds are expected to have combined properties of both the spherands and the calixarenes.The starting compound 5['] was prepared in two steps from 2,4-di-tert-butylphenol (3) by using the tert-butyl group as a positional protective group on the aromatic ring [9 -131When 5 was treated with paraformaldehyde in refluxing xylene under basic conditions['41, the expected products 4,10,17,23,30,36-hexa-twt-butyl-7,13,20,26,33,39-hexahydroxy-

Syntheses of Molybdenum and Tungsten Imido Alkylidene Complexes that Contain a Bidentate Oxo/Thiolato Ligand

“…Ultrahigh purity ethylene was purchased from Airgas and used without further purification. 3,3',5,5'-tetra-tertbutyl[1,1'-biphenyl]-2,2'-diol, [22] Mo(NAr)(CHCMe 2 Ph) (Me 2 Pyr) 2 , [23] Mo(NAd)(CHCMe 2 Ph)(Me 2 Pyr) 2 , [23] and W (NAr)(CHCMe 2 Ph)(Me 2 Pyr) 2 [24] were prepared as described in the literature. Elemental analyses were performed at the Elemental Analysis facility at the University of Rochester, New York, Midwest Microlab, Indiana, and Atlantic Microlab, Georgia.…”

One‐step syntheses of macrocyclic compounds: A short review

“…The base catalyzed condensation of 5,5'-di-t-butyl-2,2'-dihydroxybiphenyl with formaldehyde gave a calixarenelike macrocyclic compound as shown in Scheme 28 [75][76][77]. Macrocycles with three, four and eight 2,2'-dihydroxybiphenyl units have been prepared.…”

Unexpected Conformational Behaviour of a Diphosphate Derived from a Spherand‐Type Calixarene

“…[1] Macrocyclic compounds consisting of three or four methylene-linked bisphenol units 2 can be obtained by analogous condensation reactions. [2,3] Structurally, they represent intermediates between spherands (where all phenolic units are directly linked) and calixarenes (where the phenolic units are linked by methylene bridges), which explains the name "spherand-type calixarenes".…”

“…Thus, a cyclic bisphosphate 3 has been isolated from tert-butylcalix [6]arene (1b) after hydrolysis of the primary reaction products with water. [4] The same bisphosphate was obtained by acylation with ClP(O)(OEt) 2 and subsequent heating. [5] More-complex reaction products have been found for calix [4]-and calix [8]arenes 1a and 1c, where the number of hydroxy groups is not a multiple of three, while for calix [9]arenes a triphosphate with trans-cav-(RRS-twist), while a slightly higher energy was found for an RRS-crown isomer with a syn orientation of the phosporyl groups.…”