Palimécio G. Guerrero

Hydroalumination of phenylthioacetylenes. Synthesis and reactions of (Z)- and (E)-1-butyltelluro-1-phenylthio-1-alkenes

Hydroalumination of phenylthioacetylenes with the Zweifels reagent as reducing agent followed by the addition of C4H9TeBr afforded (Z)-telluro(thio)ketene acetals (Z >80–93%). The (E)-isomers were obtained with 100% stereoselectivity by reduction of thioacetylenes with DIBAL-H, followed by the addition of n-BuLi and subsequent treatment with C4H9TeBr. Reaction of the (E)-telluro(thio)ketene acetals with n-BuLi followed by the addition of valeraldehyde afforded the (Z)-phenylthio allylic alcohol as the main product and traces of the (E)-isomer, while the mixture of (Z)- and (E)-telluro(thio)ketene acetals under similar reaction conditions gave the (E)-phenylthio allylic alcohol exclusively.

Composition of leaf and rhizome essential oils of Hedychium coronarium Koen. from Brazil.

Abstract Hydrodistillation of fresh leaves and rhizomes of Hedychium coronarium collected in the Atlantic rain forest of southeastern Brazil afforded essential oils in 0.68% and 0.20% yields, respectively. Analysis of the oils by GC and GC/MS revealed as predominant constituents in the leaf oil β-caryophyllene (43.0%), caryophyllene oxide (12.1%) and β-pinene (11.6%,), whereas 1,8-cineole (34.8%), β-pinene (16.7%) and α-terpineol (13.1%) were the major components identified in the rhizome oil.

Hydroalumination of Thioacetylenes: A Versatile Generation and Reactions of α-Aluminate Sulfides Intermediates

Abstract Hydroalumination of thioacetylenes using DIBAL-H and lithium di-(isobutyl)-n-(butyl)-aluminate hydride (Zweifels reagent), followed by addition of water, furnished exclusively the (Z)- and ( E )-vinyl sulfides, respectively. The regio- and stereochemistry of the intermediates generated, (Z)- and ( E )-phenylthio vinyl alanates, were determined by capture with iodine, which afforded the corresponding ( E )- and (Z)-1-iodo-1-phenylthio-2-organoyl ethenes. Reactions of the ( E )-iodo(thio)ketene acetals with n-BuLi followed by addition of hexanal afforded the (Z)-phenylthio allylic alcohol, while the (Z)-iodo(thio)ketene acetals under similar reactions conditions gave the ( E )-phenylthio allylic alcohol exclusively.

Design, Synthesis and Anticancer Biological Evaluation of Novel 1,4-Diaryl- 1,2,3-triazole Retinoid Analogues of Tamibarotene (AM80)

We report herein the design and synthesis via click chemistry of twelve novel triazole retinoid analogues of tamibarotene (AM80) and the evaluation of their anticancer activities against six cancer cell lines: HL60, K562, 786, HT29, MCF7 and PC3. Among the synthesized compounds, two were more potent than tamibarotene against solid tumor cells, and one of them had similar potency to tamibarotene against HL60 cells. The bioisosteric exchange between the amide group and the 1,2,3-triazole core in the retinoid agent tamibarotene (AM80) reported in this work is a valid strategy for the generation of useful compounds against cancer.

Stereoselective Addition of Diethylzinc to Aldehydes Using Chiral β-Hydroxy-2-oxazolines as Catalysts

Chiral β-hydroxy-2-oxazolines were synthesized and evaluated as catalysts for the addition of diethylzinc to aldehydes. All oxazolines proved effective in obtaining the addition products. The best enantiomeric excesses (69-78%) were obtained using the chiral β-hydroxy oxazoline derived from (−)-menthone and the amino alcohol 2-amino-2-methylpropan-1-ol.