Biodegradable and biocompatible inorganic–organic hybrid materials. I. Synthesis and characterization

The hydroxyl or vinyl end-groups of linear or three-arm star-shaped poly(ε-caprolactone) (PCL) chains have been derivatized into triethoxysilane groups reactive in the sol-gel process. New transparent hybrid materials that combine tetraethylorthosilicate (TEOS) and PCL known for biodegradability and biocompatibility have accordingly been prepared. The sol-gel process is, however, limited by the early vitrification of the reactive system. However, thermal posttreatment can overcome these diffusional and/or kinetic limitations as assessed by a set of analytical methods. The thermal stability of PCL is improved by incorporation into the silica network. Conversely, the thermal stability of the ceramer depends on the effective PCL content. The extent of PCL incorporation into the silica network depends on PCL molecular weight, number, and reactivity of the PCL functional groups. IR spectroscopy has shown that hydrogen bonding occurs between the ester groups of PCL and residual OH groups of the silicate component. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2295–2309, 1997     

Metallation of benzyl selenides and of α-aryl selenoacetals. Scope and limitations.

α-Metallo benzylselenides and α-metallo selenoacetals derived from aromatic aldehydes have been conveniently prepared by metallation of the corresponding carbon acids. KDA in THF proved among the various basic systems tested, the most efficient.α-Metallo benzylselenides and α-metallo selenoacetals derived from aromatic aldehydes have been conveniently prepared by metallation with KDA of the corresponding carbon acids. These reactions have been used for the synthesis of arylalkanes, including those bearing a trialkylated benzylic carbon, from aromatic aldehydes.     

Pyrilocyanines. 36.α-thienyl substituted pyrilo- and thiopyrilocyanines

Symmetrical and nonsymmetrical 2,6- (and 4,6-)-di--thienyl substituted - and -pyrilo- and thiopyrilocyanines have been synthesized. The effect of changing the phenyl groups for -thienyl on the electronic absorption spectral parameters of the dyes obtained is discussed. It was found that such a change leads to a decrease in the effective length and increase in the electron donor ability of the hetero fragments containing these groups. The more intense coloring of the thienyl substituted dyes is due to interaction of the polymethine and quasilocal electronic transitions.For Communication 35 see [1].Institute of Organic Chemistry, National Academy of Sciences of Ukraine Kiev 253660. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 494–500, April, 1998.     

Binary and Ternary Complexes Between Lauryl Hexaoxyethylene, Benzoate and Cyclodextrin. Part I. α-CD

The characterization of binary and ternary complexes of benzoate, lauryl hexaoxyethylene (C₁₂E₆) and -CD is presented. Complexation was characterized by capillary zone electrophoresis and titration microcalorimetry. These techniques suggested that -CD formed two qualitatively different complexes with C₁₂E₆. The stoichiometric ratio of -CD : C₁₂E₆ in the individual complexes was 1 : 1 and 1.4 : 1, with stability constants of2.0 × 10³ M^-1 and 6.4 × 10⁵ M^-1.4, respectively. At higher concentrations of interacting species (10 mM), a precipitate formed. Addition of benzoate seemed to prevent precipitate formation and appeared to increase the stability constants of both binary complexes. Both techniques also indicated formation of ternary complexes between -CD, C₁₂E₆ and benzoate.     

Binary and Ternary Complexes Between Lauryl Hexaoxyethylene, Benzoate and Cyclodextrin. Part II. β-CD

The characterization of binary and ternary complexes of benzoate, lauryl hexaoxyethylene (C₁₂E₆) and -CD is presented. The complexation equilibrium was characterized by UV-Vis spectrophotometry, titration microcalorimetry, capillary electrophoresis, and 2D ROESY ¹H-NMR. Results suggested that -CD forms one complex with C₁₂E₆in the stoichiometric ratio of -CD : C₁₂E₆1.5 : 1, with a stability constant 1.3 × 10⁵ M^-1.5. The 2-D ROESY ¹H-NMR spectrum indicated that C₁₂E₆is included inside the -CD cavity. The primary binding site of C₁₂E₆ is on the lauryl subunit of this molecule. Analogous to a previously reported study of -CD, the combination of -CD and C₁₂E₆precipitated from the solution. Addition of benzoate seemed to dissolve the precipitate and nearly doubled the apparent stability constant of the complex. Results from the various techniques supported formation of ternary complexes between -CD, C₁₂E₆, and benzoate.     

Fluorine containing amino acids and their derivatives. 7. Synthesis and antitumor activity of α- and γ-substituted methotrexate analogs

Three types of reactions of α-substituted malonates, difluoromethylation, alkylation with n,n,n-trifluoroalkyl sulfonates, and Michael addition to 2-substituted-acrylates, conveniently afforded a number of fluorine containing α amino acids such as β-fluorinated-alanines, 2-amino-n,n,n-trifluoroalkanoic acids, and fluorinated glutamic acids as well as other γ-heteroatom substituted glutamic acids. Here, an efficient enzymatic optical resolution using hog kidney acylase was conducted to obtain both optical isomers of 2-amino-n,n,n-trifluoroalkanoic acids. In addition, a novel sulfoxide rearrangement was observed in a base-catalyzed reaction of diethyl α-difluoromethyl-α-sulfoxymalonates. Finally, α- and γ-substituted glutamic acids obtained were used for chemical modification of the antitumor agent methotrexate to reveal remarkable structure-activity relationships. In particular, the significant effects of fluorine substitution on the in vivo antitumor activity were observed.     

Synthesis with organoboranes. 21. Synthesis of α- and gd-bamascone

Selective syntheses of α- and gd-damascone, using allylic organoboranes as the key intermediates, are described.