Solid-phase synthesis of novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives via cyclization reactions of dithiocarboxy resin bound pyrazoles.
A general method is described for the solid-phase synthesis of novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives. The sequence developed for this purpose is based on cyclization reactions of resin-bound 3,4-functionalized-5-amino-1-dithiocarboxypyrazoles 4 and 5, promoted by reaction with various isocyanates. The resin-bound pyrazoles produced by cyclization reactions of cyanocarboimidates 8 or 3-ethoxyacrylonitriles 9 with Merrifield resin linked hydrazine dithiocarbazate 3, serve as key intermediates for subsequent bicyclic heterocycle diversification. Reactions of the resin-bound 5-amino-1-dithiocarboxy pyrazoles 4 and 5 with various aryl isocyanates produce the novel 7,8-functionalized pyrazolo[1,5-a][1,3,5]-2-oxo-4-thioxotriazine derivatives 6 and 7 in good yields and high purities.
Gong
Young-Dae
YD
Center for High Throughput Synthesis Platform Technology, Korea Research Institute of Chemical Technology, Yuseong, Daejon, Korea. ydgong@krict.re.kr
Ryu
In Ae
IA
D020650:Combinatorial Chemistry Techniques / Q000191:economics / Q000379:methods*; D003500:Cyclization; D011720:Pyrazoles / Q000138:chemical synthesis / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry; D014227:Triazines / Q000138:chemical synthesis / Q000737:chemistry*
D011720:Pyrazoles; D012117:Resins, Synthetic; D014227:Triazines