Some Chromeno[4,3-b]quinoline derivatives were synthesized in a tricomponents one-pot reaction of 1,3-cyclohexadione arylaldehydes and 4-aminocoumarin under Microwave irradiation in the solventless system by using a heteropolyacid catalyst ,H3[PW12O40] in 80-95% yields and high rates. The shorter reaction times, one-pot, good yields, simple work-up procedure and environmentally friendly conditi...

A survey is presented of the more important solution methods of the equation of the title. When space permits, a brief description of the methods and numerical examples are also given. The paper concludes with an incomplete list of 218 primitive nontrivial solutions in rational integers not exceeding 106.

In the crystal structure of the title compound, C(18)H(11)FN(4), the pyridopyrazine system makes dihedral angles of 45.51 (7) and 44.75 (7)° with the attached 4-fluoro-phenyl ring and the pyridine ring, respectively. The 4-fluoro-phenyl ring makes a dihedral angle of 54.54 (8)° with the pyridine ring. The pyridine ring part of the pyridopyrazine ring and the pyrazine ring of two c-glide-plane-r...

To reduce the size of this section's PostScript le, we have divided it into four PostScript les. We present the following index: PART 1

The crystal structure of the title compound, C(14)H(11)ClN(2)O(2)S, features a three-dimensional network stabilized by π-π inter-actions between the rings of the 4-methyl-phenyl-sulfonyl protecting group [centroid-centroid distance = 3.623 (1) Å]. The 4-methyl-phenyl-sulfonyl ring makes a dihedral angle of 79.60 (6)° with the 4-chloro-1H-pyrrolo[2,3-b]pyridine unit.

In the crystal structure of the title compound, C(18)H(11)FN(4), the pyridopyrazine ring makes dihedral angles of 34.67 (7) and 52.24 (7)° with the 4-fluoro-phenyl and pyridine rings, respectively. The 4-fluoro-phenyl ring makes a dihedral angle of 59.56 (9)° with the pyridine ring.

Mathematicians and physicists have long wondered why the Octionic Projective Plane (OP2), the Freudenthal – Tits Magic Square, or Magic Triangle and certain functions of the Octonions and Sedenions abruptly end. This paper lays out the various elements included in this conundra, with the assumption that irregularities and undiscovered relationships between these structures account for the anoma...