An Unexpected Result of Base-Promoted Rearrangement of 4a-Acetyl-8a-hydroxydecahydroquinazoline-2-thione

Treatment of 4a-acetyl-8a-hydroxydecahydroquinazoline-2-thione with NaH in acetonitrile leads to its isomerization into 1-hydroxy-1-methyl-3-thioxo-2,4-diazaspiro[5.5]undecan-7-one followed by the C1-C6 bond cleavage to give N-acetyl-N’-[(2-oxocyclohexyl)methyl]thiourea. The starting compound as a single diastereomer was prepared by the reaction between the K-enolate of 2-acetylcyclohexanone and N-(tosylmethyl)thiourea or N-(azidomethyl)thiourea

A General Stereoselective Approach to 1,2,4-Triazepane-3-thiones/ones via Reduction or Reductive Alkylation of 2,4,5,6-Tetrahydro-3H-1,2,4-triazepine-3-thiones/ones

A general stereoselective approach to previously unknown 1,2,4-triazepane-3-thiones/ones based on reduction or reductive alkylation of readily available 2,4,5,6-tetrahydro-3H-1,2,4-triazepine- 3-thiones/ones has been developed. The approach involved treatment of tetrahydrotriazepines with sodium cyanoborohydride in MeOH at pH 3 or with sodium borohydride and excess of carboxylic acid in tetrahydrofuran to give 1-unsubstituted or 1-alkyl-substituted 1,2,4-triazepane-3- thiones/ones, respectively. The latter were also prepared by reaction of 1-unsubstituted 1,2,4- triazepane-3-thiones/ones with sodium cyanoborohydride and aldehyde in MeOH in the presence of AcOH

An Unexpected Result of Base-Promoted Rearrangement of 4a-Acetyl-8a-hydroxydecahydroquinazoline-2-thione

Treatment of 4a-acetyl-8a-hydroxydecahydroquinazoline-2-thione with NaH in acetonitrile leads to its isomerization into 1-hydroxy-1-methyl-3-thioxo-2,4-diazaspiro[5.5]undecan-7-one followed by the C1-C6 bond cleavage to give N-acetyl-N’-[(2-oxocyclohexyl)methyl]thiourea. The starting compound as a single diastereomer was prepared by the reaction between the K-enolate of 2-acetylcyclohexanone and N-(tosylmethyl)thiourea or N-(azidomethyl)thiourea

A New Approach to 5-Functionalized 1,2-Dihydropyrimidin-2-ones/imines via Base-Induced Chloroform Elimination from 4-Trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones/imines

A novel four-step methodology for the synthesis of 5-acyl- and 5-arylsulfonyl-1,2-dihydropyrimidin-2-ones has been developed. The reaction of readily available N-[(1-acetoxy-2,2,2-trichloro)ethyl]-ureas with Na-enolates of 1,3-diketones, β-oxoesters, or α-arylsulfonylketones followed by heterocyclization–dehydration of the oxoalkylureas formed gave 5-acyl- or 5-arylsulfonyl-4-trichloromethyl-1,2,3,4-tetrahydropyrimidin-2-ones. The latter, in the presence of strong bases, eliminates CHCl3 to give the target compounds. The above methodology was also used in the synthesis of 5-acyl-1,2-dihydropyrimidin-2-imines starting from N-[(1-acetoxy-2,2,2-trichloro)ethyl]-N′-guanidine

Synthesis of γ‑Azido-β-ureido Ketones and Their Transformation into Functionalized Pyrrolines and Pyrroles via Staudinger/aza-Wittig Reaction

A simple two-step procedure yielding γ-azido-β-ureido ketones or/and their cyclic isomers, 6-(1-azidoalkyl)-4-hydroxyhexahydropyrimidin-2-ones, has been developed. The synthesis includes three-component condensation of acetals of 2-azidoaldehydes with urea or methylurea and <i>p</i>-toluenesulfinic acid in aqueous formic acid followed by reaction of the obtained <i>N</i>-[(2-azido-1-tosyl)­alkyl]­ureas with sodium enolates of α-functionalized ketones. The azido ketones or their cyclic isomers are transformed into ureido-substituted Δ¹- or/and Δ²-pyrrolines via Staudinger/aza-Wittig reaction promoted by PPh₃. The obtained pyrrolines are converted into 3-functionalized 1<i>H</i>-pyrroles via elimination of urea under acidic conditions. Convenient one-pot syntheses of 1<i>H</i>-pyrroles starting from <i>N</i>-[(2-azido-1-tosyl)­alkyl]­ureas or γ-azido-β-ureido ketones have been also developed

A New Convenient Synthesis of 5-Acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/ones

An efficient one-pot synthesis of 5-acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/ones is described. The synthesis is based on the reaction of readily available α-tosyl substituted thioureas or ureas with enolates of β-oxoesters or 1,3-dicarbonyl compounds followed by acid-catalyzed dehydration of the obtained 5-acyl-4-hydroxyhexahydropyrimidine-2-thiones/ones

Practical synthesis of β-isothiocyanato ketones from chalcones

<p>Practical synthesis of 1,3-diaryl-substituted 3-isothiocyanatopropan-1-ones based on the reaction of chalcones with thiocyanic acid generated in situ by treatment of thiocyanate ammonium with dilute sulfuric acid has been developed.</p

A New Convenient Synthesis of 5-Acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/ones

An efficient one-pot synthesis of 5-acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/ones is described. The synthesis is based on the reaction of readily available α-tosyl substituted thioureas or ureas with enolates of β-oxoesters or 1,3-dicarbonyl compounds followed by acid-catalyzed dehydration of the obtained 5-acyl-4-hydroxyhexahydropyrimidine-2-thiones/ones