O-Alkylation of cyclic thiohydroxamic acids 1 and 3-5 has large countercations, such as M = NBu 4 , are treated with hard alkylating reagents in polar aprotic media. (iv) As been studied with a view to developing an efficient method for the synthesis of N-(alkoxy)pyridine-2(1H)-thiones and N-tetrabutylammonium thiohydroxamates, such as 2f, are highly useful in the synthesis of cyclic thiohydroxamic acid (alkoxy)thiazole-2(3H)-thiones. Four issues have been addressed and the following conclusions can be drawn: (i)
O-esters, we have developed an efficient protocol for the preparation of N-(alkoxy)pyridine-2(1H)-thiones directly Thiones 1 and 5 exist as O-H acids in the solid state. (ii) According to NMR investigations ( 1 H, 13 C), the thione from acid 1 using phase-transfer conditions (alkyl halide or sulfonic acid ester, CH 3 CN, K 2 CO 3 , Bu 4 NHSO 4 ). This structures should be largely retained in CDCl 3 , [D 6 ]DMSO, and CD 3 OD solutions of acids 1, 3-5, as is also the case for method has proved particularly successful for the synthesis of N-(alkoxy)thiazole-2(3H)-thiones 11, 20-28, which were pyridinethione salts 2a-h. (iii) O-Alkylation of pyridinethione salts occurs in competition with S-alkylation. Selective O-obtained in yields of up to 87%. alkylation is however possible, if thiohydroxamate salts with or 6Ϫ8 should be useful, especially for the synthesis of N- [a]