Macrocycles tetraesters

Other metalloids such as tin have also been used as template ions because they form dimeric complexes which react with electrophiles to build large cyclic molecules in a 2 2 ratio (Lifson et al., 1987). Shanzer and coworkers have studied cyclizations using a dibutyltin derivative as an intermediate (Shanzer et al., 1980, 1981, 1982, 1983 Schwartz et al., 1985). The tin intermediate acts like a template to direct the diacid chloride and diol to react to form a macrocyclic tetraester as the sole cyclic product. Ninagawa and... 

The actin antibiotics, of which several are represented by the structures 1-9, occur in various Streptomyces species (1,2). The structures were elucidated as 32-membered macrocyclic tetraesters. Nonactin itself was isolated in 1955 by Prelog and his co-workers (1) as the first member of the family, and is its lowest homologue and most symmetrical member. All members of the actin family exhibit antimicrobial and antifungal activity, which increase with increasing size of R, and insecticidal activity against mites (3). 

Mandolmi, L., Montaudo, G., Scamporrino, E., Roelens, S., and Vitalini, D., Or-ganotm-Mediated Synthesis of Macrocyclic Tetraesters. A Combined H-NMR Spectroscopy, Gel Permeation Chromatography, and Fast Atom Bombardment Mass Spectrometry Approach to Complete Product Analysis, Macromolecules, 22, 3275, 1989. 

Macrocyclic tetraesters with aliphatic substituents (alkane or cycloalkane) have been synthesised analogously using both the 1,3,2-dioxastannolanic and the corresponding stibolanic derivatives as templates [16], The greater reactivity of stibolanic derivatives toward diacyl chlorides reduces considerably the reaction times and makes their use preferable. 

Recognition of ion-pair species can be achieved using a calix[4]arene tetraester functionalized with the Re(i) bipyridyl fragment. The oxygen-rich lower rim of the macrocycle in 145 was designed to act as a cation-binding site. 

Macrocyclic model lipids for the formation of vesicles often contain four ester bonds— two on each head group. It has been found that these ester bonds are exceptionally stable against acid-catalyzed hydrolysis in water. The reasons probably lie in the partial hydrophobicity of the ester group s environment, the macrocycle s order, and the reversibility of ester hydrolysis. Partially hydrolyzed tetraesters are presumably immediately reformed in vesicular membrane structures before the second, third, and fourth ester group reacts (Scheme 2.4.9). 

A further variant of this method using bismalonate tetraester allows the preparation of bis-macrocyclic amides (64) <84IC39I7>, which can be then reduced with in diglyme to the corresponding bismacrocyclic amine (65) (Scheme 7) <86102671,87JCS(D)263i>. 

Finally, some work on macrocyclic thioethers was able to show that while a metal-free tetraester of a functionalised [14]aneS4 diol was non-mesomorphic as either its cis or trans isomer, complexation to palladium(II) stiffened the whole molecular unit and allowed differentiation between the non-mesomorphic, nonlinear cis complex ((312) y = l Cr 258 I), and the mesomorphic, linear trans complex ((312) y = 1 Cr 312 (N 272) Substituted with shorter lateral arms, the palladium salts (Pd(Bp4)2) exhibited monotropic SmC phases ((312) y = 0 Cr 222 (SmC 164) I). Difunctionalized tru 5-[16]aneS4 diol palladium ((313) MX = Pd(BF4)i, y = 0,l) also exhibited monotropic phase (SmC and N, respectively for y = 0 and 1), whereas the copper derivative ((313) y = 0, MX = Cu(PF6)) was surprisingly devoid of mesomorphism. Note that some related aza macrocyclic metal complexes as potential metallomesc ens were also studied, but it appeared that none of them were found to be mesomorphic. ... 

Macrocyclic polyether di- or tetraester ligands containing pyrazole units. 

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