Reported herein is the first example of a gold-catalyzed cyclization of bis­(arylmethyl)­ethynylphosphine oxides. This represents an original approach to bridgehead methanophosphocines 1, eight-membered heterocycles. Gold catalyst in combination with triflic acid activates alkyne and induces a double hydroarylation. Mechanistic studies suggest that the reaction proceeds stepwise, forming first the 1H-isophosphinoline 2-oxide 5. Reduction and protection of the corresponding phosphine oxides 1 described herein also highlight the effectiveness of our approach to this new class of electron-rich ligands.

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The scheme of formation of bicyclic phosphonates 3 synthesized on the basis of resorcinol and its derivatives was suggested based on the model reactions of dichloroanhydride 1 with 3‐methoxyphenol 7 in the presence of triethylamine with a variable ratio of reagents. Composition and structure of the products obtained were confirmed according to 1H and 31P NMR, IR spectroscopy, elemental analysis, and X‐ray analysis. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:340–344, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21022

Reaction of resorcinol with phosphorylated acetals or ethoxyvinylphosphonic acid esters in acidic media leads to calix[4]resorcinarenes, containing dialkoxyphosphoryl fragments at the lower rim of the molecule. When the alkyl substituent in alkoxy groups at phosphorus atom is not very long, a partial hydrolysis of the initially formed products takes place to give calixarenes with alkoxyhydroxyphosphoryl fragments.Exploration of chemistry of calix[n]arenes, in particu lar calix[4]resorcinarenes, is one of the most promising and intensively developing trends in organic chemistry. 1-3 The simplicity of their synthesis and the ability to form complexes of the "guest-host" type with various in struc ture organic compounds and metal ions, as well as the tendency to self association, leading to supramolecular ensembles, are the conditions of it. All the properties described above make this class of compounds very pro spective from the point of view of creation of new types of complex forming agents and the metal ions extragents, as well as new catalytic systems. The most widely used ap proach to the formation of calixarene matrix includes the reaction of polyphenols with aldehydes and their deriva tives. However, it has certain limitations, since the ques tion about influence of the starting aldehyde and polyphe nol structures on the composition of the forming final products is not entirely clear. It is known 4-6 that un substituted aliphatic and aromatic aldehydes, as well as aliphatic aldehydes with functional substituents, separated from the reaction center by four-eight carbon atoms, afford calix[4]resorcinarenes by condensation with resor cinol in acidic media. At the same time, such structures are not formed in the reaction of α halogen substituted aliphatic aldehydes with resorcinol. 5 Within the frame work of approach under discussion, there is no informa tion about a possibility of the synthesis of calixarenes by the reaction of resorcinol with aldehydes, containing func tional substituents, separated from the carbonyl group by two-three carbon atoms.Calix[4]resorcinarenes, bearing phosphoryl substi tuted alkyl groups at the lower rim of the molecule, are of particular interest as complex forming agents and extragents. Methods for the preparation of compounds of this type are not described in the literature, which, appar ently, is mainly connected with the difficulties in the synthesis of phosphorylated aliphatic aldehydes. It should be also noted that so far the attempts to obtain calixarenes, bearing phosphorus containing alkyl fragments at the lower rim of the molecule, by phosphorylation of the already made calixarene matrix failed and it is doubtful whether such an approach will be implemented in the nearest future. We came to a conclusion that the synthesis of calix [4]resorcinarenes, phosphorylated at the lower rim of the molecule, most likely can be fulfilled during forma tion of calixarene matrix. Since, as it was already men tioned above, phosphorylated aldehydes are not easily available, we tried to ...

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