Reaction of 6-amino-2-thiouracil 1 with ethyl bromoacetate yielded ethyl 2-(7-amino-2,5-dioxo-3,5dihydro-2H-thiazolo[3,2-a]pyrimidin-6-yl)acetate 2. Reaction of 2 with sodium ethoxide afforded the pyrrolothiazolopyrimidine derivative 3. Compound 2 reacted with hydrazine hydrate to give 7-aminothiazolopyrimidine-carbohydrazide 4. The latter compound 4 reacted with carbon disulphide to form 7-amino-6-(oxadiazolylmethyl) thiazolopyrimidine 5. Compound 5 was heated in methanol to yield 9-thioxotriazolopyrrolothiazolopyrimidine 6.Also,thereactionof 3witharomaticaldehydesaffordedthe diarylmethylenepyrrolothiazolopyrimidine derivatives 7a-c. The latter compounds 7a-c underwent cyclocondensation with hydroxylamine to give diaryldioxazolopyrrolothiazolopyrimidine derivatives 8a-c. The new prepared compounds were subjected for antioxidant and antituomer studies, some of these compounds exhibited promising activity.

Synthesis, Antioxidant, Antituomer Activities of Some New Thiazolopyrimidines, Pyrrolothiazolopyrimidines and Triazolopyrrolothiazolopyrimidines Derivatives

Synthesis and biological evaluation of some thio containing pyrrolo [2,3-d]pyrimidine derivatives for their anti-inflammatory and anti-microbial activities.

Synthesis, in vitro antimicrobial and in vivo antitumor evaluation of novel pyrimidoquinolines and its nucleoside derivatives

Publisher Summary This chapter reviews the chemistry of 1,2,4-triazolopyrimidines. The chapter is devoted to surveying the chemistry of one of the four possible systems of this class of compounds—namely, 1,2,4-triazolo[4,3-a]pyrimidin. The chapter focuses on the chemistry of 1,2,4-triazolo[1,5-c]pyrimidines. This chapter discusses the introduction, synthesis, reactions, spectral properties, and applications of 1,2,4-triazolopyrimidines 11: 1,2,4-triazolo[4,3-c]pyrimidines. It also illustrates that many members of the 1,2,4-triazoIo[4,3-c]pyrimidines are shown to possess very interesting biological activities and medicinal applications. The chapter concludes by discussing that 1,2,4-triazoIo[4,3-c]pyrimidines have been synthesized using several general approaches: (1)annulation of the 1,2,4-triazole ring onto a pyrimidine structure; (2) annulation of the pyrimidine ring onto a 1,2,4-triazole structure; (3) concurrent formation of both of the 1,2,4-triazole and pyrimidine rings; and (4) rearrangement of pyrimido[5,4-e]l,2,4-triazines.

The Chemistry of 1,2,4-Triazolopyrimidines I: 1,2,4-Triazolo[4,3-a]Pyrimidines

Publisher Summary This chapter reviews the chemistry, biological significance, and uses of 1,2,4-triazolo- and tetrazolo-[x,y-zl pyrimidines. The arrangement of each ring follows the order of the site of fusion on the pyrimidine ring, denoted by the letter t, and the site of fusion on the triazole ring, denoted by the letters x and y . The classification of the subdivisions is dependent upon the extent of published work. There are four possible isomeric structures: (1) 1,2,4-triazolo[4,3-a] pyrimidines, (2) 1,2,4-triazolo[4,3-c]pyrimidines, (3) 1,2,4-triazolo[l,5-a] pyrimidine, and (4) 1,2,4-triazolo[1,5-c] pyrimidines. A characteristic feature triazolopyrimidines is the ease of a Dimroth rearrangement. 1,2-Diaminopyrimidines are general precursors, and they can be generated from 1-amino or 2-aminopyrimidines. The synthesis of 1,2,4-triazolo[4,3-a] pyrimidines ring system may be achieved by building the triazole onto a preformed pyrimidine ring. The synthesis from pyrimidines, triazoles, reactivity, physicochemical data, uses, and biological properties of all these rings are discussed in the chapter.

A. M. Hassan Rezk

Papers

Reactions with 2‐mercaptopyrimidines. Synthesis of some new thiazolo[3,2‐a]‐ and triazolo[4,3‐a]pyrimidines