Reaction of S-methiodide derivatives of activated thioureas with hydroxylic compounds. Novel synthesis of mercaptans

Abstract

2-Methyl-2-thiopseudourea hydriodides activated by electron-withdrawing groups undergo attack by alcohols and water to give several types of products whose formation is dependent on the nature of the hydroxylic reactant. When l-benzoyl-2-methyl-2-thiopseudourea hydriodide (5) was heated with alcohols, methyl mercaptan was evolved and there was formed 1-benzoylurea (2) and the iodide corresponding to the alcohol. The yield of 2 was diminished and the formation of l-benzoyl-2-thiourea (1) took on greater prominence in going from a primary to a tertiary alcohol. Methyl JV-benzoylthiolcarbamate (6) and NHJ were also formed when the more hindered alcohols were used and were essentially the only products obtained in the reaction of 5 with water.S-Methiodide derivatives of other activated thioureas, i.e., l-acetyl-2-methyl-2-thiopseudourea (9), 2-methyl-2-thiopseudobiuret (10), 2-methyl-2,4-dithiopseudobiuret (11), and 1-(4-nitropheny 1 )-2-methy 1-2-thiopseudourea (12) hydriodides, reacted with ethanol and water in a similar manner as 5. Thiols could be generated in moderate yields by the reaction of l-acetyl-2-thiourea ( 14) with primary alkyl halides in ethanol.

Selective Palladium‐Catalysed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides using PCy3 as Ligand

“…The residue was purified by column chromatography on silica gel (hexane/ethyl acetate, gradient from 100:0 to 80:20). [17] White solid, 31 mg (77 %). [18] White solid, 41 mg (97 %).…”

“…[19] White solid, 32 mg (76 %). [17] White solid, 40 mg (95 %). [21] Light yellow solid, 33 mg (78 %).…”

Total Synthesis of TAN-1057 A/B, a New Dipeptide Antibiotic fromFlexibacter sp. PK-74

“…2:1). Ϫ Major isomer (common signals are marked with *), 1 (18) was synthesized according to the published procedure [12] [13] . (19): A suspension of the amino acid 15 (505 mg, 2.00 mmol) and the isothiuronium salt 18 (1.044 g, 4.00 mmol) in water (5 ml) was treated under stirring with 2  aqueous NaOH until pH 11 was reached, and the clear solution was stirred at room temp.…”

“…Therefore N α -methyl--asparagine (13) was protected by reaction with benzyl chloroformate (ZCl) to give the com-Scheme 3 pound 14. The Z-protecting group was preferred at this stage as it can be cleaved hydrogenolytically, while the Bocdeprotection requires strongly acidic conditions and the sixmembered ring in TAN-1057 (and probably its precursors) is sensitive towards acidic hydrolysis.…”

“…The isothiuronium salt 18, chosen as a reagent to introduce the N-carbamoylamidino function, was obtained from monothiobiuret (17) (Scheme 4) as described earlier [12] [13] . Although there was no information in the literature on reactions of 18 with amines to form carbamoylguanidines, a very similar "thiocarbamoylguanidination" of amines with the thioanalog of 18 was described recently [14] .…”