Multi-stage Reactions in One-pot using Inorganic Supported Reagents

我们已经研究了两个阶段的反应，在一锅使用无机支持试剂的假设，两个试剂在均匀的溶液中相互反应，使相互不活跃的支持他们到单独的无机支持。两步合成应该是可能的，其中可溶性试剂（A）首先与一种负载的试剂（Y）反应，产物（B）与第二种负载的试剂（X）反应，得到所需的最终产物（C）。通常，2-氨基噻唑通过α-卤代酮与单取代硫脲的缩合或通过α-硫氰基羰基化合物与芳族或脂族胺盐酸盐的反应来制备。本文报道了用KSCN/SiO_2-RNH_3AcO/Al_2O_3体系从α-卤代酮一锅法合成2-氨基噻唑的简便方法。α-卤代酮先与KSCN/SiO_2反应生成α-硫氰酸酯，后者再与RNH_3AcO/Al_2O_3反应生成2-氨基噻唑。我们还研究了以β-二酮和硫醇为原料，在CuBr_2/Al_2O_3-NaOH/Al_2O_3体系中一锅法合成α-烷硫基-β-二酮的反应。β-二酮与CuBr_2/Al_2O_3反应生成α-溴代-β-二酮，再与硫醇在碱NaOH/Al_2O_3存在下反应生成α-烷硫基-β-二酮。

We have investigated two-stage reactions in one-pot using inorganic supported reagents on the assumption that two reagents reacting each other in homogenous solution are rendered mutually inactive by supporting them onto separate inorganic supports. It should be possible that two-step synthesis, in which a soluble reagent (A) react first with one supported reagent (Y) and the product (B) with the second supported reagent (X) to give the desired final product (C). Typically, 2-aminothiazoles are prepared either by the condensation of α-halo ketones with monosubstituted thioureas or by the reaction of α-thiocyanato carbonyl compounds with aromatic or aliphatic amine hydrochlorides. We have developed a convenient method for the preparation of 2-aminothiazoles in one-pot from readily available α-halo ketones using supported reagents system KSCN/SiO_2-RNH_3AcO/Al_2O_3. α-Halo ketones react first with KSCN/SiO_2 affording α-thiocyanates, the latter moving to RNH_3AcO/Al_2O_3 and reactins with it to give the end product 2-aminothiazoles. We have also developed one-pot synthesis of α-alkylthio-β-diketones from-β-diketones and thiols using supported reagents system CuBr_2/Al_2O_3-NaOH/Al_2O_3. β-Diketones react with CuBr_2/Al_2O_3 to give α-bromo-β-diketones, and then the bromides react with thiols in the presence of the base NaOH/Al_2O_3 to afford the end product α-alkylthio-β-diketones.