Thermolysis of N-arylnicotinamide oximes 1a–c (R = H, CH3 and Cl) under nitrogen gives rise to benzimidazoles
3a–c as the major products (60–62%), in addition to nicotinonitrile 4, arylamines 5a–c, nicotinic
acid 6, phenols 7a–c and 8a–c, nicotinanilides 9a–c, 2-(pyridin-3-yl) benzoxazoles 10a and carbazoles
11a–c. In the presence of naphthalene, thermolysis of 1a gave - and -naphthols 12 and 13 beside the
previous products. Also pyrolysis of 1a in boiling tetralin lead to the formation of 1-hydroxytetralin 14,
-tetralone 15 and 1,1-bitetralyl 16 as the major products. The isolated products have been interpreted
in the terms of a free radical mechanism involving the homolysis of N–O and/or C–N bonds.

Thermolysis of N-phenylbenzamide oximes I, II and III (R = Cl, NO2 and OCH3) under nitrogen gives rise
to benzimidazoles as the major products (45–52%), in addition to benzonitrile, arylamines, benzoic acid,
phenols, benzanilides, 2-phenyl benzoxazoles and carbazoles. In the presence of naphthalene, I gave
- and -naphthols beside the previous products. Also heating of I under reflux boiling tetralin lead to
the formation of 1-hydroxytetralin, -tetralone and 1,1-bitetralyl as the major products. The isolated
products have been interpreted in the terms of a free radical mechanism involving the homolysis of N–O
and/or C–N bonds.

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.