Hetero Diels–Alder trapping of 3-methylene-1,2,4-[3H]naphthalenetrione: an efficient protocol for the synthesis of α- and β-lapachone derivatives

Site-selectivity control in hetero-Diels-Alder reactions of methylidene derivatives of lawsone through modification of the reactive carbonyl group: an experimental and theoretical study

A new perspective on the reactivity of hydroxyquinones was revealed as an acetal derivative of lawsone was synthesized, isolated, and used in tandem Knoevenagel/hetero-Diels-Alder reactions catalyzed by S-proline. The intermediate alkylidene-1,3-diones that were formed in situ reacted with electron rich alkenes to predominantly afford pyrano-1,2-naphthoquinone (β-lapachone) derivatives along with the isomeric pyrano-1,4-naphthoquinone (α-lapachone) derivatives in high to excellent total yields. Interestingly, the highly reactive arylidene-1,3-dione derivatives were found to be stable and isolable. DFT calculations suggest that these hetero-Diels-Alder reactions have a high polar character, taking place through a two-stage one-step mechanism. An analysis of the conceptual DFT indices allows explaining the remarkable site-selectivity observed.

Lawsone in organic synthesis

Lawsone has been used as the starting material for the synthesis of a variety of biologically active compounds and materials.

Development of an alkaloid-pyrone annulation: synthesis of pleiomaltinine

Odd Couple

Methodology for the synthesis of alkaloid-pyrones using a novel pyrone annulation of β–carbolines and indoles with 3-siloxy-4-pyrones is reported. The approach has enabled semisynthesis of the unprecedented alkaloid-pyrone pleiomaltinine from the plant-derived indole-alkaloid pleiocarpamine.

Synthesis and anti-Trypanosoma cruzi activity of β-lapachone analogues

The available chemotherapy for Chagas disease, caused by Trypanosoma cruzi, is unsatisfactory; therefore, there is an intense effort to find new drugs for the treatment of this disease. In our laboratory, we have analyzed the effect on bloodstream trypomastigotes of 16 new naphthoquinone analogues of β-lapachone modified in the pyran ring, aiming to find a new prototype with high trypanocidal activity. The new compounds presented a broad spectrum of activity, and five of them presented IC(50)/24 h in the range of 22-63 μM, whereas β-lapachone had a higher value of 391.5 ± 16.5 μM.

Antiplasmodial Activity of Naphthoquinones Related to Lapachol andβ-Lapachone

The in vitro antiplasmodial activity of 26 naphthoquinone derivatives related to the natural lapachol (1) and beta-lapachone (2) was tested. Ten of these derivatives are reported for the first time. The evaluation was performed on cultures of F32 strain of Plasmodium falciparum, and some derivatives displayed attractive in vitro activities (IC50 < 10 microM). Based on these results, some structure-activity relationships have been determined.