Several Rhodamine B derivatives based on a tri-substituted pyrimidine core were prepared using solid-phase chemistry. Some derivatives exhibited fluorescence also at high pH and showed significant mitochondrial localization.

Derivatives of 3-methyl-3,6-dihydro-2H-1,2-oxazine-6-carboxylic acid prepared by regioselective hetero Diels-Alder reaction of arylnitroso compounds with sorbic acid were used for solid-phase synthesis of a library of derivatives that included modification of carboxylic group, dihydroxylation of double bond and cleavage of N-O bond. Derivatives of 2,3,4-trihydroxyhexanoic acid obtained from 3,6-dihydro-2H-1,2-oxazines after double bond dihydroxylation and N-O cleavage were used for simple and stereoselective formation of chiral lactones derived from 3,4-dihydroxydihydrofuran-2(3H)-one. The final compounds obtained as a mixture of stereoisomers were analyzed with use of chiral HPLC and SFC. HPLC analyses were not successful for all derivatives or required lengthy chromatography. On the other hand SFC afforded much shorter analyses and was effective for all studied derivatives. The method of synthesis and analysis is thus suitable for future study of stereoselective synthesis of lactones and other derivatives from single oxazine derivatives and application of high-throughput synthesis on solid-support and combinatorial chemistry.

Rearrangement of some anthranilic acid esters, thioesters or amides under particularly acidic conditions gives derivatives of 2-aryl-3-substituted-quinolinon-4(1H)-ones. The reaction represents undoubtely the most efficient method for the preparation of derivatives bearing hydroxy and amino group at position 3. Furthermore, the target compounds comprise organic molecules with very interesting biological properties that have been reviewed quite recently. This mini-review summarizes information about limits and scopes of the unprecedent reaction that became extremely useful and revolutionary in area of flavonoids analogues research.

4-Chloro-2-fluoro-5-nitrobenzoic acid is a commercially available multireactive building block that can serve as a starting material in heterocyclic oriented synthesis (HOS) leading to various condensed nitrogenous cycles. This work describes its ability for the preparation of substituted nitrogenous heterocycles having 5-7-membered cycles via polymer-supported o-phenylendiamines. Immobilization of this compound on Rink resin followed by further chlorine substitution, reduction of a nitro group and appropriate cyclization afforded benzimidazoles, benzotriazoles, quinoxalinones, benzodiazepinediones and succinimides. The method developed is suitable for the synthesis of diverse libraries including the mentioned types of heterocycles, which have significant importance in current drug discovery. In this paper, we also report limitation of these method and unsuccessful attempt to prepare an 8-membered benzodiazocine cycle.

Base-catalyzed rearrangement of 2H-indazoles 1-oxides, prepared by tandem carbon-carbon followed by nitrogen-nitrogen bond formations from easily accessible N-alkyl-2-nitro-N-(2-oxo-2-aryl-ethyl)-benzenesulfonamides using glycine, 2-nitrobenzenesulfonyl chlorides, and bromo ketones/acetates, yielded high purity quinazolines.

The efficient solid-phase synthesis of 3-hydroxy-2,7-disubstituted-6-nitroquinolin-4(1H)-ones using Rink amide resin is described. Synthesis starts from immobilized 4-chloro-5-nitroanthranilic acid which, after the nucleophilic replacement of the chlorine atom with various amines and subsequent esterification with bromoacetophenones, afforded substituted phenacylanthranilates. Their cyclization by heating in sulfuric acid gave corresponding hydroxyquinolinones of excellent purity.

The preparation of various 5-[alkoxy-(4-nitro-phenyl)-methyl]-uracils with alkyl chain lengths C1–C12 is described. The synthesis is based on the preparation of 5-[chloro-(4-nitro-phenyl)-methyl]-uracil and subsequent substitution of chlorine with appropriate alcohols. The resulting ethers were tested for their cytotoxic activity in vitro against five cancer cell lines. The compounds were less active in lung resistance protein expressing cell lines, suggesting the involvement of this multidrug resistant protein in control of the biological activity. Cytotoxic substances induced rapid inhibition of DNA and modulation of RNA synthesis followed by induction of apoptosis. The data indicate that the biological activity of 5-[alkoxy-(4-nitro-phenyl)-methyl]-uracils depends on the alkyl chain length.