Synthesis of seleniumcontaining amino acid analogues is described. These compounds were prepared in a concise and short synthetic route in good yields by nucleophilic substitution reaction of pyridineselenol and quinolineselenol derivatives with Nphthaloylglycyl chloride followed by hydrazinolysis. The newly synthesized compounds were screened against different strains of bacteria and fungi.

The compound of selenium containing heterocycles namely (I) 4,6-dimethyl-3-cyanopyridine-(2H)- selenone (C8H8N2Se) was used as model to investigate the structural and micro-structural features of some selected selenones. Visualization of molecular structure of selenium containing moiety was accurately investigated to clarify role of selenium ion in nucleation process of forming 3D-framenet of H-bonded of substituted selenones. Bond distances, torsions on angles of investigated compound were compared with others crystal data to confirm crystal structures of substituted selenones which is monoclinic crystal form with P21/n space group.

Selenium has long been recognized as a dietary antioxidant and is now known to be an essential component of the active sites of several enzymes, including glutathione peroxidase [2] and thioredoxin reductase, which catalyze reactions essential for the protection of cellular components against oxidative and radical damage [3]. Moreover, previous work in our laboratory describes the synthesis of pyrimidoselenolo- [2,3-b]quinoline [4] and pyrimidoselenolo[2,3-c]pyridazine derivatives [5] and indicates that certain compounds possess significant anti-inflammatory and analgesic activities with strong fungicidal effects. Furthermore, in Part 1 [6] and Part 2 [1] we published the synthesis of selenolo[2,3-b]pyridine, pyrido[3',2':4,5]selenolo- [3,2-d]pyrimidine, 2,4-dimethyl-7,8-dihydropyrrolo[1,2-a]pyrido[3',2':4,5]selenolo[3,2-d]pyrimidin-10(6H)-one, 7,9-dimethylpyrido[3',2':4,5]selenolo[3,2-e][1,2,4]triazolo[4,3-c]pyrimidine, 7,9-dimethylpyrido[3',2':4,5]selenolo[ 3,2-d]pyrimidine-2,4(1H,3H)-dithione, 7,9-dimethylpyrido[3',2':4,5]selenolo[2,3-e]tetrazolo[1,5-c]pyrimidine- 6(5H)thione, 9,11-dimethylpyrido[3',2':4,5]selenolo[2,3-e][1,2,4]triazolo[1,5-c]pyrimidine, 7,9-dimethylpyrido[ 3',2':4,5]selenolo[2,3-e]imidazo[1,2-c]pyrimidine, and 10,12-dimethylpyrido[3'',2'':4',5']selenolo- [3',2':4,5]pyrimido[1,6-a]pyrimidine derivatives. Prompted by these observations and in continuation of our work we report herein new classes of fused tri- and tetracyclic systems containing the selenolo[2,3-b]pyridine fragment in the hope that members of these series may find interesting biological applications.

Selenium has attracted great interest as an essential element, and certain diseases have been eradicated by dietary supplementation of this element. Selenium is essential for cell metabolism as a component of glutathione peroxidase and other enzyme systems. Current interest lies in the prevention of certain cancers by supplementation with selenium [1–4]. One proposed mechanism for this activity is the cytotoxic effect of selenium on tumor cells [5, 6]. Organoselenium compounds continue to attract the attention of many investigators owing to a series of unique properties. There are data showing that organoselenium compounds are capable of sensitizing processes in the living organism, and there are four known naturally occurring proteins containing the selenium atom. Therefore, despite the high toxicity of selenium compounds [7–9], many of them have been prepared as and anticancer agents [10–15] and for other medicinal effects like antiviral [16–18], antimicrobial [19–22], and fungicidal [23–25] activities. Heterocyclic annelated pyridazines also attract considerable attention, which arises mainly from the large variety of interesting pharmacological, herbicidal, insecticidal, and fungicidal activities [26–30]. In the last two decades we have been involved in a program aimed at developing new synthesis of heterocyclic systems of anticipated biological and/or pharmacological effects [31–37]. In continuation of this program, some selenium-containing heterocyclic compounds were required for evaluation as biodegradable agrochemicals. The starting compound 4-cyano- 5,6-diphenylpyridazine-3(2H)- selenone 1, which was prepared as previously described [38] seemed suitable to fulfill this objective.

This paper presents U–Pb ID-TIMS geochronological data from granitoids in the Hafafit area in the Central and South Eastern Desert, Egypt. It dates several Neoproterozoic magmatic pulses and metamorphic events, and constrains one episode of U, Nb and Ta mineralisation along the Nugrus Shear Zone, part of the Eastern Desert Shear Zone, to 608±1 Ma. The data testify to the localized nature of deformation in the Eastern Desert, illustrating that previous subdivisions of granitoids into “Older” and “Younger” based on field criteria are inadequate. With robust ages fromgranitoids in theMeatiq, El Sibai and El Shalul areas the newages indicate 6 pulses of magmatism and/or metamorphism at (1) 705–680, (2) c. 660, (3) 635–630, (4) 610–604, (5) 600–590 and (6) c. 540 Ma. Most pulses are defined by ages from granitoids in both gneiss windows/domes and in the overlying eugeoclinal allochthon; the two tiers represent different crustal levels of related rocks. We propose that pulses 1–3 are syn-orogenic, pulses 4 and 5 reflect exhumation of mid-crustal gneisses along the Eastern Desert Shear Zone, whereas the final pulse post-dates the East African orogeny. Based on available data we propose that the tectono-magmatic evolution above applies to the entire Eastern Desert.

This paper presents U–Pb ID-TIMS geochronological data from granitoids in the Hafafit area in the Central and South Eastern Desert, Egypt. It dates several Neoproterozoic magmatic pulses and metamorphic events, and constrains one episode of U, Nb and Ta mineralisation along the Nugrus Shear Zone, part of the Eastern Desert Shear Zone, to 608±1 Ma. The data testify to the localized nature of deformation in the Eastern Desert, illustrating that previous subdivisions of granitoids into “Older” and “Younger” based on field criteria are inadequate. With robust ages fromgranitoids in theMeatiq, El Sibai and El Shalul areas the newages indicate 6 pulses of magmatism and/or metamorphism at (1) 705–680, (2) c. 660, (3) 635–630, (4) 610–604, (5) 600–590 and (6) c. 540 Ma. Most pulses are defined by ages from granitoids in both gneiss windows/domes and in the overlying eugeoclinal allochthon; the two tiers represent different crustal levels of related rocks. We propose that pulses 1–3 are syn-orogenic, pulses 4 and 5 reflect exhumation of mid-crustal gneisses along the Eastern Desert Shear Zone, whereas the final pulse post-dates the East African orogeny. Based on available data we propose that the tectono-magmatic evolution above applies to the entire Eastern Desert.