One-step synthesis of rccc- and rctt-diastereomers of novel calix[4]resorcinols based on a para-thiophosphorylated derivative of benzaldehyde Irina R. Knyazeva a,⇑ , Victoria I. Sokolova a , Margit Gruner b , Wolf D. Habicher b , Victor V. Syakaev a , Vera V. Khrizanforova a , Bulat M. Gabidullin a , Aidar T. Gubaidullin a , Yulia H. Budnikova a , Alexander R. Burilov a , Michael A. Pudovik a a A.E. Arbuzov Institute of Organic and Physical Chemistry of Kazan Scientific Center, Russian Academy of Sciences, Arbuzov Str. 8, Kazan 420088, Russia b Institute of Organic Chemistry, Dresden University of Technology, Mommsenstr. 13, Dresden D-01062, Germany article info Article history: Received 21 February 2013 Revised 18 April 2013 Accepted 26 April 2013 Available online 3 May 2013 Keywords: Thiophosphorylated calix[4]resorcinol Condensation Resorcinol Aldehyde Conformation abstract Novel calix[4]resorcinols with four 2-thioxo-1,3,2-dioxaphosphorinane fragments included in aromatic substituents have been synthesized via a one-step condensation of resorcinol and its derivatives with a new para-thiophosphorylated benzaldehyde. It has been found that the diastereomeric ratio depends substantially on the reaction conditions, in particular, the solvents and catalysts used. The macrocyclic products obtained are rctt- and/or rccc-isomers, which were isolated and the structures determined by NMR and single crystal X-ray diffraction studies. Ó 2013 Elsevier Ltd. All rights reserved. The design of phosphorus-containing macrocyclic compounds including calixarenes is an important area of development in con- temporary organoelement chemistry. 1 The introduction of func- tional groups with a phosphorus atom of varying coordination in the macrocycle allows the synthesis of substances with three- dimensional architecture. Organophosphorus fragments having high coordination ability can enhance substantially the particular properties of a macromolecule or give it completely new features. For example, modification of the calix[4]arene matrix with func- tional groups containing phosphorus and sulfur atoms allows a remarkable improvement of the extraction ability of the deriva- tives obtained compared to their unsubstituted precursors, with respect to soft metal ions, specifically, Ag + , Co 2+ , Cu 2+ , Zn 2+ , Pb 2+ , and Hg 2+ . 2 A general method for the synthesis of calix[4]resorcinols in- volves the acid-catalyzed condensation of resorcinol or its deriva- tives with aliphatic or aromatic aldehydes. 3 The macrocyclic compounds formed can exist as four diastereomers, namely, rccc, rcct, rctt, and rttt, which are differentiated by the spatial orienta- tion of the substituents of the calixarene matrix relative to the macrocyclic cavity. The ratio of diastereomers usually depends on the nature of the initial aldehyde and the reaction conditions. For example, condensation of resorcinol with long-chain aliphatic aldehydes gives predominantly the rccc-isomer in high yields, and the use of aromatic aldehydes leads to a mixture of rccc- and rctt-isomers. Recently, we realized for the first time the highly effective single- step synthesis of P = S-substituted calix[4]resorcinols containing four diethyl thiophosphate or 2-thioxo-1,3,2-dioxaphospholane groups on the aromatic substituents, which was based on the con- densation of new thiophosphorylated derivatives of benzaldehyde with resorcinol or its derivatives in acidic media. 4 It was shown that the reactions proceeded stereoselectively in moderate to high yields with formation of only the isomer of calixarene in chair conforma- tion with rctt-configuration of the thiophosphorylated substituents. It should be noted that the introduction of thiophosphoryl groups on the calixarene framework has so far been a labor-consuming process, and involved predominantly the addition of a sulfur atom to trivalent phosphorus atoms, which had been previously intro- duced on the upper rim of calix[4]resorcinols or cavitands via O-phosphorylation. 2b,5 In order to design thiophosphorylated calix[4]resorcinols as functionalized partners in the reaction with resorcinol and its derivatives, we used for the first time 2-(4-formylphenoxy)-2-thi- oxa-5,5-dimethyl-1,3,2-dioxaphos-phorinane (3), which was syn- thesized in a yield of 88% by the reaction of 2-chloro-2-thioxo- 1,3,2-dioxaphosphorinane (1), synthesized according to a known 0040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.tetlet.2013.04.114 ⇑ Corresponding author. Tel.: +7 9178804234. E-mail address: ihazieva@mail.ru (I.R. Knyazeva). Tetrahedron Letters 54 (2013) 3538–3542 Contents lists available at SciVerse ScienceDirect Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet