An eco-friendly protocol for synthesis of thiourea derivatives: 1-benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl- O-ethylisourea. A possible non-purely thermal microwave assisted reaction

• Published in: Tetrahedron Vol. 62; no. 11; pp. 2616 - 2621
• Main Authors: Marquez, Heiddy, Loupy, André, Calderon, Osmar, Pérez, Eduardo R.
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 13.03.2006; Elsevier
• Subjects: 1-Benzoyl-3-benzyl- O-ethylisourea; 1-Benzoyl-3-benzylguanidine; Chemistry; Chemistry, Organic; Microwave irradiation; Physical Sciences; Science & Technology; Solvent-free conditions; Thiocarbamates; Microwave irradiation; 1-Benzoyl-3-benzylguanidine; 1-Benzoyl-3-benzyl- O-ethylisourea; Solvent-free conditions; Thiocarbamates; REAGENT; ORGANIC-SYNTHESIS; O-ALKYLISOUREAS; thiocarbamates; SOLID-PHASE SYNTHESIS; HGCL2-PROMOTED GUANYLATION REACTION; ONE-POT SYNTHESIS; ALKYLATION; 1-benzoyl-3-benzylguanidine; 1-benzoyl-3-benzyl-O-ethylisourea; GUANIDINES; CYCLOADDITIONS; ESTERS; microwave irradiation; solvent-free conditions
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2005.12.037

1-Benzoyl-3-benzylguanidine and 1-benzoyl-3-benzyl- O-ethylisourea were synthesized in good yields (68 and 76%, respectively) from 1-benzoyl-3-benzylthiourea and benzoyl-ethylthiocarbamate in dry media conditions using KF–Al 2O 3 under microwave irradiation. Strong nucleophilic amines promoted the sulfur elimination by attack on the thiocarbonyl group in both thiourea and thiocarbamates to afford guanidines and isourea, respectively. Transesterification products were obtained from p-TsOH catalyzed reaction of thiocarbamate with alcohols under MW-solvent-free conditions. Very important non-purely thermal MW specific effects were evidenced and attributed to stabilization by coulombic interactions between materials and waves. Graphical Abstract