β-Phenylethylamine-Derived Amides from Piper guayranum

Abstract

The acetone extract of the aerial parts of Piper guayranum yielded tembamide acetate [1] and alatamide [2] but not tembamide [3]. Compound 1 has not been previously reported as a natural product while both 2 and 3 has only been encountered so far in species of Rutaceae.Piper guayranum C.DC. (Piperaceae) is a tall, slender shrub that is found in shady, elevated regions of Trinidad, Tobago, and Venezuela (1). There is no record of folkloric medicinal use of this plant, and there appear to be no reported chemical studies either. We wish to report the results of our studies on the aerial parts of P. guayranum occurring in Trinidad.Repeated vacuum liquid chromatography (vie) of the Me2CO extract resulted in the isolation of three crystalline compounds. The most polar compound 1 was obtained as white needles, mp 159°( petroleum ether/Me2CO). High resolution eims gave an [M]+ (at mlz 313 -1308) which indicated a molecular formula of C18H19N04 ([M}+ calculated 313.1314). Four bands, at 208, 225, 270, and 278 nm, were observed in the uv spectrum. The ir spectrum exhib-OMe ited absorptions at 3315, 1727, 1645, 1532, and 1510 cm-1 indicating the presence of both amide and ester groups.*H nmr (Table 1) suggested a 1,4-disubstituted aromatic ring (AB type fourproton doublet of doublets at 6.92 and 7.35) as well as a monosubstituted one (five-proton multiplet at 7.45-7.83).Acetate (three-proton singlet at 2.12) and aromatic methoxy (three-proton singlet at 3.82) groups were also indicated. On complete exchange after the

Highly Enantioselective Synthesis of Propargyl Amides through Rh-Catalyzed Asymmetric Hydroalkynylation of Enamides: Scope, Mechanism, and Origin of Selectivity

“…Moreover, many naturally occurring molecules contain enamide structure (Scheme ). , When the current asymmetric alkynylation is applied to Z -alatamide, the product was afforded in good yield and enantioselectivity, although a higher reaction temperature was necessary. Lansiumamide A contains two electronically distinct alkenes, an electron-rich alkene and an electron-deficient alkene.…”

Antifungal piperamides from Piper mollicomum Kunth (Piperaceae)

“…ALAIN 15 , Aegle marmelos 16 , Clausena lansium 17 , and Feroniella lucida 18 . This amide was also obtained by hydrolysis from tembamide acetate isolated from the dichloromethane fraction of Piper guayranum (Piperaceae) 19 , a plant species traditionally used in Indian medicine due to its hypoglycemic activity 20 . In addition, tembamide displayed one of the most potent activities against HIV virus among 67 substances isolated from the bark and root of Zanthoxylum ailanthoides (Rutaceae) 21 .…”

Synthesis of Secondary Enamides by Ruthenium‐Catalyzed Selective Addition of Amides to Terminal Alkynes

“…Enamides thus accessible in only one step from easily available materials include the natural products lansiumamide A (3 s) [2] and alatamide (4 t), [5] the previously published syntheses of which involved three to four steps and lower product yields. This also applies to compound 3 u, which is a key intermediate in Castedos total synthesis of aristolactam.…”

“…and biologically active natural products, such as lansiumamide A, [2] TMC-95A-D, [3] crocacin, [4] alatamide, [5] aspergillamides A-B, chondriamide C, lobatamides A-F, and a range of marine metabolites. [6] Furthermore, they are versatile synthetic intermediates for the synthesis of heterocycles, [7] crosscouplings, [8] and Heck reactions.…”

“…Other ruthenium precursors were found to be even less effective (entries 2, 3). Solvent screening revealed that DMF was uniquely effective, resulting in an increase in yield (entries [4][5][6]. Based on the reasoning that the coordination of a Lewis acid to the carbonyl oxygen would acidify the amide protons, and therefore serve the same purpose as an added base, we replaced DMAP by a Lewis acid (entries 9, 10).…”