Mauro Taveira Magalhães

Diasin, A diterpene from Croton diasii

Abstract The trunkwood of Croton diasii Pires (Euphorbiaceae) contains diasin, a novel rearranged labdanic diterpene which includes furan, carbomethoxy, γ

Constituintes químicos de Tovomita brasiliensis ()

The trunk wood of Tovomita brasiliensis Walp. from Belem, Para State, contains 1,5-dihydroxy-6.7-dimethoxyxanthone, betulinic acid and sitosterol. The additional presence of 8-hydroxy-3,5-dimethyl-3.4-dihydroisocoumarin, 8-hydroxy-5-methoxy-3-methyl-3,4-dihydroisocoumarin and 7-chloro-8-hydroxy-6-methoxy-3-methylisocoumarin in the benzene extract is most probably due to infestation of the plant material by fungi.

Structure and absolute configuration of the sesquiterpenoid emmotins

Abstract The trunk wood of Emmotum nitens (Icacinaceae) contains the aromatic sesquiterpenes (2R,3S)-2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethyl-1-oxo-1,2,3,4-tetrahydronaphthalene (emotin-F), 2-hydroxy-3-(2′-hydroxyisopropyl)-5,8-dimethylnaphthalene (emmotin-G) and 3-(2′-hydroxyisopropyl)-5,8-dimethyl-1,2-naphtho-quinone (emmotin-H). The identity of the carbon skeletons of these emmotins was proved by conversion of all three into an identical quinoxaline derivative. The nature of this skeleton and the absolute configuration of emmotin-F, as well as of the previously described emmotins A and B, was established by conversion of emmotin-F into (+)-occidol.

Naturally Occurring Aromatic Derivatives of Monocyclic α-Pyrones

Condensed ring α-pyrones (coumarins and their derivatives) are widely distributed in nature and have been reviewed extensively (26, 76). In recent years the apparently much less numerous monocyclic α-pyrones have attracted considerable attention. These can be conveniently divided into two classes, according to their substituents: terpenoid and aromatic. The first include the toad poisons and squill glucosides and have already been the object of comprehensive progress reports (30, 82). On the other hand, a review of the aryl-pyrones and their partially hydrogenated derivatives is still lacking. They are the subject of the present article.

The reaction of 1-nitro-2-phenylethane with alkali

Abstract Ammonia, hydrocyanic acid, benzaldehyde, benzoic acid, phenylacetic acid and 2,5-diphenylpyrazine were identified among the products of the reaction of 1-nitro-2-phenylethane with alkali. A reaction mechanism is proposed to account for their formation.