ChemInform Abstract: Synthesis and Mutagenic Properties of Tetrahydropyranyl‐ and Tetrahydrothiopyranylpyrazoles and ‐pyrimidines.

Abstract

The (thio)pyranylpyrazoles (III), prepared from the malononitrile derivatives (Ia) or the cyanoacetates (Ib) and the hydrazines (II), have mutagenic activity.

Kost-Sagitullin Rearrangement and Other Isomerization Recyclizations of Pyrimidines. (Review)

“…In 1982 Vartanyan and coworkers were able to subject 2-mercapto-and 2-amino-5-ethoxycarbonyl-4-methylpyrimidines 71b,c to such a transformation. Under the influence of an alcohol solution of sodium ethoxide they rearranged into the corresponding 5-acetyl-4-hydroxypyrimidines 72b,c [115]. However, in the cited papers, both then and later, neither the above-mentioned nor other authors have made any attempts to study such transformations in greater detail.…”

Recyclization of Condensed Carbethoxypyrimidines Accompanied by Substitution of a Carbon Atom into the Heterocycle

“…Evidently, in the recyclization process under the action of hydroxide ion there occurs a fission of the pyrimidine ring at the N-C (7) bond, subsequent rotation around the C (5) -C (6) single bond, and repeated recyclization. As a result, the ester group C atom is included in the newly formed pyrimidine ring while the C (7) atom which was situated in the pyrimidine ring appears outside the heterocycle.…”

“…As a result, the ester group C atom is included in the newly formed pyrimidine ring while the C (7) atom which was situated in the pyrimidine ring appears outside the heterocycle.…”

“…Hence in the example of 6-carbethoxy-7-methylpyrazolo[1,5-a]pyrimidines a possible transformation route might be a conversion to a pyrazolo [3,4-b]pyridine derivative by a Kost-Sagitullin type rearrangement [9] via fission of the N-C (7) bond of the pyrimidine ring and subsequent cyclization by attack at the C (4) atom of the azole. However, in the conditions indicated above we were unable to separate the expected reaction products.…”

“…A similar rearrangement has previously been noted in a series of 2-substituted 5-carbethoxy-4-methylpyrimidines. Upon heating in sodium ethylate solution they are converted to the corresponding 2-substituted 5-acetyl-4-hydroxypyrimidines [7]. We have previously shown [8] that 2-substituted 4-amino-5-carbethoxypyrimidines are converted to the corresponding 5-carbamoyl-5-hydroxypyrimidines by treatment with base.…”