Ciclização do lapachol induzida por sais de tálio III

Abstract

Recebido em 29/11/07; aceito em 7/3/08; publicado na web em 9/4/08 CYCLIZATION OF LAPACHOL INDUCED BY THALLIUM SALTS. This work describes the cyclization of lapachol (1) induced by thallium triacetate (TTA) and thallium trinitrate (TTN) in several solvents using magnetic stirring and under microwave irradiation. α-Xyloidone (2) -dehydro-α-lapachone -was obtained as the main product in these reactions in 20 -75% yield. However, rhinacanthin-A (4) was isolated as main product in a 40% yield, using TTA and acetic anhydride:water (1:1) as solvent, and dehydroiso-α-lapachone (3) in 21% yield, using TTA and dichloromethane as solvent. The reaction time decreased drastically under microwave conditions, but the yields of these reactions were not the expected.

Antifungal and Antiplasmodial Activity of Isolated Compounds from Handroanthus serratifolius (Vahl) S. Grose Sawdusts

“…In previous studies with heartwood from H. serratifolius, dehydro-α-lapachone was detectados by GC/MS as predominant compound 20 . The 1 H and 13 C NMR spectral data allowed identification of 2 as dehydro-iso-αlapachone whose data were similar to those published by Ribeiro et al 21 . Identification of lignans 4 and 5 was based on experiments 1 H and 13 C NMR, and HMBC.…”

Claisen Rearrangement of Hydroxynaphthoquinones: Selectivity toward Naphthofuran or α‐Xiloidone Using Copper Salts and Iodine

“…One of the most interesting chromenes, due to its biological activity , is α‐xiloidone 2 . Structurally, this compound is a naphthoquinone, related to lapachol, which is usually isolated from the bark of trees belonging to the family Bignoneacea . α‐Xiloidone has the 2,2‐dimethylchromene structure, which is found in many natural derivatives.…”

Structural and reactivity analyses of 2-benzylamino-1,4-naphthoquinone by X-ray characterization, electrochemical measurements, and dft single-molecule calculations

“…Functionalized 1,4-naphthoquinones is a theme of ongoing interest due to their potential in the synthesis of heterocyclic compounds [1][2][3][4] as well as for their pharmacological applications. [5][6][7] In this context, amino-naphthoquinones, which has embedded in their structure the N-C=C-C=O enaminone moiety, have been synthesized and tested for pharmacological activities.…”