SHORT COMMUNICATIONSNatural hydroxy carboxylic acids possessing an asymmetric carbon atom are accessible chiral synthons. Among biologically active α-hydroxy acids, lactic acid attracts particular attention. It inhibits growth of putrefactive bacteria [1] and is used in medicine and veterinary as sodium, potassium, calcium, ammonium, and magnesium salts; calcium lactate is used for the treatment of calcium deficiency and as a styptic; iron(II) lactate is active in the treatment of anemia [2]; (R)-lactate is a component of antitumor agents [3]. Methyl (S)-(-)-lactate (1) used as a source of chirality in asymmetric synthesis [4] may also be involved in the preparation of phosphorus dithio acids [5] exhibiting antimicrobial activity.
Reactions of 2,4-diaryl-1,3-dithia-2λ 5 ,4λ 5 -diphosphetane 2,4-disulfides with tetraheptylcalix[4]-resorcinarene and octa-O-(2-hydroxyethyl)tetraoctylcalix[4]resorcinarene gave the corresponding octakis(aryldithiophosphonic acids). R = C 7 H 15 ; Ar = 3,5-di-tert-butyl-4-hydroxyphenyl (a), 4-phenoxyphenyl (b).Calixarenes can be functionalized at the hydroxy groups to change the size and geometric shape of the cavity and its ability to effectively and selectively bind ions and neutral molecules. In the series of calixarenes functionalized at the hydroxy groups by heteroatom moieties, much attention is given to cavitands phosphorylated at lower and upper rims [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. On the other hand, thiophosphorylated calixarene derivatives were studied to a considerably lesser extent. They were synthesized mainly via addition of sulfur to the corresponding phosphorylated calixarene derivatives with three-coordinate phosphorus atoms [15]. Prior to our studies dithiophosphorylated calixarenes were not reported in the literature. Nevertheless, such compounds attract interest as complexing agents, extractants, antioxidants, corrosion inhibitors, etc. We propose to obtain such compounds via reactions of calixarenes with 2,4-diaryl-1,3-dithia-2λ 5 ,4λ 5 -diphosphetane 2,4-disulfides as thophosphorylating agents. It is known that 2,4-dialkyl-or 2,4-diaryl-1,3-dithia-2λ 5 ,4λ 5 -diphosphetane 2,4-disulfides react with alcohols, diols, and other polyhydric alcohols at the O-H bonds with formation of aryldithiophosphonic, bis-aryldithiophosphonic, and poly-aryldithiophosphonic acids [16][17][18][19][20][21][22][23][24]. Calix[4]resorcinarene II reacted with 2,4-diaryl-1,3-dithia-2λ 5 ,4λ 5 -diphosphetane 2,4-disulfides Ia and Ib at a molar ratio of 1 : 4 in benzene to give octa-O- (2,4,6,8-tetraheptyl-1,3,5,7(1,3)-tetrabenzenacyclooctaphane-1 4 ,1 6 ,3 4 ,3 6 ,5 4 ,5 6 ,7 4 ,7 6 -octayl) octakis(hydrogen arylphosphonodithioates) IIIa and IIIb (Scheme 1).The reaction with diphosphetane disulfide Ia was complete in 10 h at 20°C, whereas heating of the reaction mixture for 20 h at 60°C was necessary to obtain compound IIIb. The 31 P NMR spectrum of IIIa contained a singlet at δ P 88.1 ppm, while the signal of compound IIIb with 4-phenoxyphenyl substituents on the phosphorus atoms was displaced upfield (δ P 81.7 ppm). Such chemical shifts are typical of di-
The use of ultrasonic irradiation in the reactions of trialkyl borates with octahydroxytetraoctyl[l 4 ] metacyclophane allowed us obtaining tetraalkoxyboratocavitands with higher yields and under milder conditions. We first obtained 1,3,2-dioxaborolane and 1,3,2-dioxaborinane derivatives of tetraoctyl[l 4 ]metacyclophane using ultrasonic irradiation. Boratocavitands were converted into the corresponding amine complexes with isobutylamine.Since recently, an increased attention is paid to structural, chemical, physicochemical aspects and application of the class of calixarene compounds. This is due to the existence of a hydrophobic cavity in the molecules of these compounds that is capable of complexing with the molecules of neutral organic compounds and ions [1][2][3][4]. Due to the presence of hydroxy groups, the calixarenes can be subjected to functionalization, which leads to a change in the size and geometry of the cavity and its ability of effective and selective bonding. The calixarenes whose molecules include a hetero-element may have practical value as a complexing agents and metals extractants, and can serve as the models of enzymatic and other biochemical processes. Among the calixarenes with the elements introduced through the HO groups the most attention attracted the cavitands O-and Cphosphorylated at the lower and upper rims [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. At the same time, other calixarenes of the O-element type (O-sulfonylated [20], O-and C-silylated [21-26] and O-borylated cavitands [27]) have been less studied.It is known that the reaction of calixresorcynols with triisobutyl borate in boiling toluene leads to the formation of tetraalkoxyborato-cavitands [28]. In order to increase the reactivity of borates in these reactions we exerted ourselves to search for initiators of these transformations. We have previously shown that the reaction of thiophosphorylation of trialkyl borates under ultrasonic irradiation occurs considerably faster,
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