Microwave assisted synthesis of 5-hydroxy-5-trichloromethyl-4,5-dihydroisoxazoles
摘要:
A series of 13 5-hydroxy-5-trichloromethyl-4,5-dihydroisoxazoles have been synthesized in 78-96% yield by environmentally benign microwave induced techniques involving the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alken-2-ones [CCl3C(O)C(R-2)=C(R-1)OR, where R-2=H, alkyl; R-1=H, alkyl, aryl and R=H, alkyl] with hydroxylamine using toluene as solvent. The advantages obtained by the use of microwave irradiation in relation to a classical method were demonstrated. (C) 2002 Elsevier Science Ltd. All rights reserved.
使用三氯甲基取代基作为方便的离去基团,用于合成有趣的双杂环化合物,一系列6-甲基和7-烷基(芳基)-5 H-噻唑并[3,2- a ]嘧啶-5-酮,其中烷基=甲基,正丙基,异丙基,异丁基,正己基,异戊基和芳基=苯基,通过4-烷氧基-的简单和区域特异性反应获得4-甲苯基,4-氯苯基,4-溴苯基,4-甲氧基苯基。 1,1,1-三氯-3-烯丙基-2-酮与2-氨基噻唑的收率良好(45–89%)。
A simple and convenient one-pot procedure for the synthesis of 5- and 6-substituted 2-phenyl-3 H-pyrimidin-4-ones by the condensation of 4-alkoxy-1,1,1-trichloroalk-3-en-2-ones with benz-amidine hydrochloride is described.
ABSTRACT The one-pot synthesis of nine 5-trichloromethyl-1,2-dimethyl-1H-pyrazolium chlorides 2 from the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alken-2-ones [CCl3C(O)C(R2)= C(R1)OR, where R1 = H, Me, Et, n-Pr, (CH2)5CO2Et, CH2Br, Ph, 4-Br-C6H4; R2 = H, Me; and R = Me, Et] with 1,2-dimethylhydrazine is reported. For Part 16, see Ref. [12].
A series of five 5-trichloromethyl-1-phenyl-1H-pyrazoles and six 5-trichloromethyl-1,2-dimethylpyrazolium chlorides have been synthesized in 80-98% yield by environmentally benign microwave induced techniques involving the cyclocondensation of 4-alkoxy-1,1,1-trichloro-3-alken-2-oneS [Cl3C(O)C(R-1)=C(R-1)OR, where R-2=H, Me; R-1=H, alkyl, phenyl and R=Me, Et] with phenyl hydrazine and 1,2-dimethylhydrazine dihydrochloride, respectively, using toluene as solvent. The use of microwave and classical methods are comparable for making pyrazoles, but the formation of pyrazolium chlorides can be achieved in a significant shorter time, and in some cases better yield. (C) 2003 Elsevier Ltd. All rights reserved.