Table of Contents

Abstract: n/a

Abstract: A stereoselective synthesis of (6Z, 11Z)-octadecadienoic acid (1) and (6Z, 11Z)-eicosadienoic acid (2) from easily accessible pentane-1,5-diol (3) is described. Thus, compound 3 on pyranylation and oxidation gave the aldehyde 5 which was converted to the acid 7 by Wittig reaction with a suitable phosphorane. Its depyranylation and oxidation furnished the key aldehyde 9 which upon Wittig reaction with n-heptylidene and n-nonylidene phosphoranes, respectively followed by alkaline hydrolysis afforded the title acids.

Abstract: 2-Chloro-1,3-dithiane was obtained by the chlorination of 1,3-dithiane with N-chlorosuccinimide. Reactions of 2-chloro-1,3-dithiane with various substituted phenols lead to 2-(1,3-dithianyl)phenols (3). Hexakis-[p-(1,3-dithian-2-yl)phenoxy]cyclotriphosphazene (6) was obtained by reaction with hexachlorotriazacyclotriphosphazene (5).

Abstract: Irradiation of pentafluoroiodobenzene and alkenes gave the corresponding adducts. The presence of single electron-transfer scavengers, (p-dinitrobenzene and t-Bu₂NO) and the free radical inhibitor (hydroquinone) suppressed the reaction. A photoinduced electron-transfer mechanism is proposed.

Abstract: The synthesis of combinatorial compound libraries has become a powerful lead finding tool in modern drug discovery. The ability to synthesize rapidly, in high yield, new chemical entities with low molecular weight on a solid support has a recognized strategic relevance (“small molecule libraries”). We designed and validated a novel solid phase synthesis scheme, suitable to generate diversity on small heterocycles of the pyrazole and isoxazole type. Appropriate conditions were worked out for each reaction, and a variety of more or less reactive agents (building blocks) was utilized for discrete conversions, in order to exploit the system’s breadth of applicability. Four sequential reaction steps were validated, including the loading of the support with an acetyl bearing moiety, a Claisen condensation, an a-alkylation and a cyclization of a b-diketone with monosubstituted hydrazines. In a second stage, the reaction sequence was applied in a split and mix approach, in order to prepare a combinatorial library built-up from 4 acetyl carboxylic acids (R¹), 35 carboxylic esters (R²) and 41 hydrazines (R⁴) (and 1 hydroxylamine) to yield a total of 11,760 compounds divided into 41 pyrazole sublibraries with 140 pairs of regioisomers and 1 isoxazole sublibrary of equal size.