Selective Mono- or Dialkoxylation of 2,4,6-Trichloro-1,3,5-triazine in Solid-Liquid Phase Transfer Conditions

Design, Synthesis, and Utility of Defined Molecular Scaffolds

A growing theme in chemistry is the joining of multiple organic molecular building blocks to create functional molecules. Diverse derivatizable structures—here termed “scaffolds” comprised of “hubs”—provide the foundation for systematic covalent organization of a rich variety of building blocks. This review encompasses 30 tri- or tetra-armed molecular hubs (e.g., triazine, lysine, arenes, dyes) that are used directly or in combination to give linear, cyclic, or branched scaffolds. Each scaffold is categorized by graph theory into one of 31 trees to express the molecular connectivity and overall architecture. Rational chemistry with exacting numbers of derivatizable sites is emphasized. The incorporation of water-solubilization motifs, robust or self-immolative linkers, enzymatically cleavable groups and functional appendages affords immense (and often late-stage) diversification of the scaffolds. Altogether, 107 target molecules are reviewed along with 19 syntheses to illustrate the distinctive chemistries for creating and derivatizing scaffolds. The review covers the history of the field up through 2020, briefly touching on statistically derivatized carriers employed in immunology as counterpoints to the rationally assembled and derivatized scaffolds here, although most citations are from the past two decades. The scaffolds are used widely in fields ranging from pure chemistry to artificial photosynthesis and biomedical sciences.

In vitro cytotoxic activities of 2-alkyl-4,6-diheteroalkyl-1,3,5-triazines: new molecules in anticancer research

The cytotoxic activities of new 2-alkyl-4,6-dihetero(N,O)alkyl-1,3,5-triazines toward selected tumor cell lines have been evaluated, and for the first time, the potential of 2-alkyl-4,6-dialkoxy-1,3,5-triazines has been shown.

Triazine-based condensing reagents

The synthesis, properties, and application of condensing reagents derived from 1,3,5-triazines are described. The mechanism of activation of carboxylic function, structure of reactive intermediates, and mechanism of acylation of nucleophiles are presented. The synthetic versatility of mono- and bifunctional reagents for syntheses in solution, triazine-based immobilized reagents, chiral triazines for enantiodifferentiating syntheses, are discussed. The scope and limitation of the synthetic utility of triazine reagents in the preparation of heterocyclic compounds, amides, esters, oligopeptides-including large-scale syntheses and use in the combinatorial chemistry-is demonstrated.

New chiral stationary phases based on (R)-1-naphthylethylamine bound to 2,4,5,6-tetrachloro-1,3-dicyanobenzene

Chiral functionalization of 2,4,5,6-tetrachloro-1,3-dicyanobenzene (1) by regioselective nucleophilic substitution of one or two chlorine atoms by optically pure (R)-(+)-1-naphthylethylamine (NEA), or by a glycine unit as a spacer to (R)-NEA, enables the preparation of brush-type chiral selectors (2, 3, 9, 13). By the introduction of the 3-aminopropyltriethoxysilyl (APTES) group, reactive intermediates 4a/b, 5, 10a/b, and 14a/b are obtained (a/b indicate a mixture of regioisomers with APTES in 6- and 2-position). Binding of these to silica gel afforded four novel chiral stationary phases (CSPs) 6, 7, 15, and 16. HPLC columns containing CSPs with (R)-NEA directly linked to polysubstituted aromatic ring (6, 7) are not very effective in resolution of most of the 23 racemic analytes, whereas the columns with distant pi-basic subunits (15, 16) exhibited higher resolving efficacy, in particular towards the isopropyl esters of racemic N-3,5-dinitrobenzoyl-alpha-amino acids. Effective resolution of test racemates reveals the importance of the presence of the hydrogen bond donor amido group and the distance between the persubstituted benzene ring in 1 and the pi-basic naphthalene ring of (R)-NEA. Copyright 1999 Wiley-Liss, Inc.