Adriana L. Brachet-Cota and Gerardo Burton* Departamento de Qirimica Orgänica, Facultad de Cieneias Exaetas y Naturales, Universidad de Buenos Aires, Pabellön 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina Z. Naturforsch. 43b, 491-495 (1988); received November 2, 1987 6/3-Hydroxypregnanes, Mercuric Oxide, Oxidation, /3-Fragmentation. Hypoiodite Reaction Oxidation of 6/3-hydroxyprogestero...

Efficient direct synthesis of macrodiolides via catalysis using Hf(OTf)4 is possible in high yields, forming water as the sole by-product. The first protocol for the direct synthesis of macrodiolides from equimolar mixtures of diols and dicarboxylic acids was developed (58-96%). In addition, modification of the reaction concentration allows for the synthesis of head-to-tail macrodiolides from t...

Neste trabalho investigou-se a reação entre fluoreto de tetrametilamônio seco (TMAF) e 1metil-2,4,5-tribromoimidazol em diferentes solventes apróticos polares. Nas reações feitas em DMSO, N,N-dimetilacetamida e N-metilpirrolidona, os principais produtos foram provenientes da desbrominação redutiva e não da fluoração, como esperado, mostrando que o TMAF é fortemente básico nestas condições. A re...

Two new abietane type diterpenoids, namely seco-helioscopinolide (1) and 3b,7b-dihydroxy-ent-abieta-8,13-diene-12,16-olide (2) were isolated from the aerial parts of Euphorbia formosana Hayata together with helioscopinolide A (3), helioscopinolide B (4), helioscopinolide C (5) and ent-(5b,8a,9b,10a,12a)-12-hydroxyatis-16-ene-3,14-dione (6). The structures of compounds 1-6 were elucidated by ana...

A new atisane-type diterpene, ent-16alpha-hydroxy-atisane-3,4-lactone (4) and three known diterpenes, ent-16alpha-hydroxy-atisane-3-one (1), ent-atisane-3beta,16alpha-diol (2), ent-3,4-seco-16alpha-hydroxyatis- 4(19)-en -3-oic acid (3) were isolated from the bark of the mangrove plant Excoecaria agallocha. Their structures and relative stereochemistry were elucidated by means of extensive NMR a...

Atriplex nummularia (Lindl.) es un arbusto utilizado como recurso forrajero estratégico en sistemas ganaderos de zonas áridas y semiáridas época estival. El 2019 se crearon dos módulos seguimiento esta especie el sur Chile; las localidades Los Sauces (secano interior, 37° latitud sur) Carillanca (valle central seco, 38° sur). Se evaluó crecimiento durante 3 años (2019-2021) calidad forrajera de...