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1.
J Org Chem ; 88(15): 11140-11149, 2023 Aug 04.
Article in English | MEDLINE | ID: mdl-37463494

ABSTRACT

An efficient and controlled site-selective annulation of 3,5-diethoxycarbonyl 4-hydrazonyl pyrazoles is described. The relative proportion of the products is affected by hydrazone intermediate configuration, reaction temperature, and Lewis acid employed. At a temperature of 110-120 °C, the reaction preferentially afforded 1H-pyrazolo[3,4-d]pyridazin-7(6H)-ones, whereas using Yb(OTf)3 in MeCN reflux, 2H-pyrazolo[3,4-d]pyridazin-7(6H)-ones were favored. Computational investigations were performed to clarify the mechanism and the origin of the regiodivergence.

2.
ChemistryOpen ; 10(10): 931-938, 2021 10.
Article in English | MEDLINE | ID: mdl-34331350

ABSTRACT

A series of 60 4-aminomethyl 5-aryl-3-substituted isoxazoles were synthesized by an efficient method and evaluated in vitro against Leishmania amazonensis and Trypanosoma cruzi, protozoa that cause the neglected tropical diseases leishmaniasis and Chagas disease, respectively. Thirteen compounds exhibited a selective index greater than 10. The series of 3-N-acylhydrazone isoxazole derivatives bearing the bithiophene core exhibited the best antiparasitic effects.


Subject(s)
Antiprotozoal Agents , Leishmaniasis , Trypanosoma cruzi , Antiprotozoal Agents/pharmacology , Antiprotozoal Agents/therapeutic use , Humans , Isoxazoles/therapeutic use , Leishmaniasis/drug therapy , Structure-Activity Relationship
3.
Org Biomol Chem ; 18(13): 2524-2537, 2020 04 01.
Article in English | MEDLINE | ID: mdl-32196053

ABSTRACT

A simple and efficient methodology for highly regioselective synthesis of azomethine pyrazoles and isoxazoles containing a trifluoromethyl group is reported. The cyclocondensation of trifluoromethylated ß-enamino diketones (TBED) with phenylhydrazine and hydroxylamine hydrochloride, in the presence of BF3, provided 5-aryl-4-[(tert-butyl)iminomethyl]-3-trifluoromethylazoles by aza-Michael-type 1,2-addition. The scope of the reaction was expanded by transimination with arylamines in a one-pot method starting from TBED. Thus, 83 novel 4-[(alkyl/aryl)iminomethyl]-3-trifluoromethylazoles were obtained with high regioselectivity and in yields of 51 to 89%.

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