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.
A Convenient Preparation of 4-Methyl- and 4-Phenylseleno-1,1,1-trihalo-3-alken-2-ones and their Usefulness in the Synthesis of 3-Trihalomethylisoselenazoles
作者:Marcos A. Martins、Giovani P. Bastos、Adilson P. Sinhorin、Nilo E. Zimmermann、Helio G. Bonacorso、Nilo Zanatta
DOI:10.1055/s-2002-34854
日期:——
reaction of 4-methylseleno- 1,1,1-trihalo-3-alken-2-ones with bromine and ammonia lead to 3-trihalomethylisoselenazoles in good yields. The usefulness of the trichloromethylgroup as a carboxyl group precursor was demonstrated by the conversion of 5-ethyl-3-trichloromethylisoselenazole to 5-ethyl-3-carboxyisoselenazole acid.
β-Alkoxyvinyl trichloromethyl ketones as N-heterocyclic acylating agent. A new access to 5H-thiazolo[3,2-a]pyrimidin-5-ones
作者:Helio G Bonacorso、Rogério V Lourega、Arci D Wastowski、Alex F.C Flores、Nilo Zanatta、Marcos A.P Martins
DOI:10.1016/s0040-4039(02)02337-7
日期:2002.12
Using trichloromethyl substituent as convenient leaving group for the synthesis of interesting bi-heterocyclic compounds, a series of 6-methyl- and 7-alkyl(aryl)-5H-thiazolo[3,2-a]pyrimidin-5-ones, where alkyl=methyl, n-propyl, isopropyl, isobutyl, n-hexyl, isopentyl and aryl=phenyl, 4-toluyl, 4-chlorophenyl, 4-bromophenyl, 4-methoxyphenyl was obtained from a simple and regiospecific reaction of 4-alkoxy-1
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 Convenient Synthesis of 5- and 6-Substituted 2-Phenyl-3<i>H</i>-pyrimidin-4-ones
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 one-pot synthesis of ethoxycarbonylpyrazoles 2a-e, by the cyclocondensation of β-alkoxyvinyl trichloromethyl ketones 1a-e with hydrazine hydrochloride under mild conditions, is reported. A study using compounds 1a-e with different substituents proved that these are versatile building blocks for the synthesis of pyrazole derivatives, having a 3(5)-ethoxycarbonyl substituent, in good yields (70-91%).