Polarized ethylenes. IV. Synthesis of polarized ethylenes using thioamides and methyl dithiocarboxylates and their application to syntheses of pyrazoles, pyrimidines, pyrazolo[3,4‐d]pyrimidines, and 5‐aza[2.2.3]cyclazines

Abstract

Polarized ethylenes having both electron‐donating (an amino or a methylthio group) and electron‐accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S‐alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields. These polarized ethylenes were alternatively synthesized by the reaction of thioamides or methyl dithiocarboxylates with tetracyanoethylene oxide in good yields. Reactions of these polarized ethylenes with hydrazine or guanidine derivatives occurred smoothly to give the corresponding pyrazole and pyrimidine derivatives in good yields. The synthesis of 5‐aza[2.2.3]cyclazine derivatives using polarized ethylenes is also described.

Electron ionization (EI) mass spectra of Exo-Endo double-bond isomers of polycyano “push-pull” pentadienes derived from cycloalkylidene malonic acid derivatives

“…These fragmentations may reflect intramolecular cyclization of the M ϩ⅐ ions similar to the thermally induced cyclizations that have been previously described in push-pull alkenes bearing a pyrrole substitu- ent [8 -10]. Depending on whether the compounds are derived from malonodinitrile [8,9] or from cyanoacetic esters [10], their thermal cyclizations could involve the loss of ROH (Scheme 3). Since numerous analogies are known between the thermally induced intramolecular reactions and mass-spectrometric fragmentations, we assume this to be the case in Compounds 5-12 as well.…”

Synthesis of 4-amino-5-cyano-2, 6-Disubstituted Pyrimidines as a Potential Antifilarial DNA Topoisomerase II Inhibitors

“…Five compounds (12)(13)(14)(15)(16) having 4-chloro-phenyl substitutent at position-6 showed 90-95% inhibition at 40 g/mL concentration and at 5 g/mL concentration, these compounds have 70-80 % inhibitory activity. Surprisingly, compounds (17,18) bearing 4-chloro-phenyl substitutent with the aminobenzyl and the 3-imidazol-1-yl-propylamine at position-2 respectively showed weak inhibition. It is interesting to note that the compounds having 4-chloro-phenyl substitutent are more potent than the compounds with 4-fluorophenyl group.…”

“…Knoevenagel condensation reaction was carried out between the different aldehydes (1) and malononitrle (2) in the presence of piperidine in ethanol to yield the corresponding benzylidine malononitriles (3a-d). Compounds (3a-d) were cyclised with S-methylisothiourea sulfate in the presence of K 2 CO 3 in methanol to give 2-thiomethyl-4-amino-5-cyano-6-aryl pyrimidines (4a-d) according to the reported procedure with slight modification [17,18]. Compounds (4a-d) were further oxidized to corresponding sulfones (5a-d) in the presence of m-chloroperoxybenzoic acid.…”

Sulfonic Acid-Functionalized Lus-1: An Efficient Catalyst for One-Pot Synthesis of 2,4-Diamino Pyrimidine-5-Carbonitrile Derivatives

“…15 There are only few reports for the synthesis of 2,4-diamino pyrimidine-5-carbonitriles via multicomponent reactions of aldehydes, malononitrile and guanidine. [16][17][18][19][20][21] However, many of these reported methods suffer from drawbacks such as long reaction times, formation of side products, multistep synthesis, the use of organic solvents, large amount of catalyst and catalysts that cannot be recycled. In continuation of our previous works on the application of heterogeneous solid catalysts in organic synthesis, [22][23][24][25][26][27][28][29][30][31] herein, we would like to report a highly efficient method in the synthesis of 2,4-diamino pyrimidine-5-carbonitriles using LUS-Pr-SO 3 H under solvent-free conditions.…”