Securinega Alkaloids Research Articles

A New Enantioselective Approach to Total Synthesis of the Securinega Alkaloids: Application to (-)-Norsecurinine and Phyllanthine.

An inexpensive proline derivative and chiral control feature in the total synthesis of securinega alkaloids (-)-norsecurinine (1) and phyllanthine (2). Key steps in the synthesis of 1 include an intramolecular ketonitrile coupling and application of a radical-based generation of N-acylimines. The total synthesis of 2 utilizes a stereoselective imino Diels - Alder construction of the methoxypiperidine ring.

A New Enantioselective Approach to Total Synthesis of the Securinega Alkaloids: Application to (−)-Norsecurinine and Phyllanthine

Ein preiswertes Prolinderivat und Chiralitätskontrolle spielen in der Totalsynthese der Securinega-Alkaloide (−)-Norsecurinin 1 und Phyllanthin 2 eine Rolle. Zu den Schlüsselschritten der Synthese von 1 gehören eine intramolekulare Ketonitrilkupplung und eine radikalchemische N-Acylimin-Bildung. Teil der Totalsynthese von 2 ist der stereoselektive Aufbau des Methoxypiperidinrings durch eine Imino-Diels-Alder-Reaktion.

ChemInform Abstract: Development of Methodology for Amide Oxidation and Its Application to Total Synthesis of Securinega Alkaloids

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Synthesis of the securinega alkaloids (±)-norsecurinine and (±)-Nirurine from 3-hydroxypyridine.

Treatment of the dihydropyridine 5 with fluoride anion resulted in in situ formation of the allenyldiene 4 which cyclized to the azabicyclo[2.2.2]octene 9. Subsequent elaboration to the alcohol 24 and rearrangement gave norsecurinine 2. The intermediate diol 16 was converted into prenirurine 34 which upon conversion into an N-oxide rapidly rearranged to give traces of nirurine 1 and norphyllanthine 38.

Viroallosecurinine and ent-Phyllanthidine From the Leaves of Breynia coronata (Euphorbiaceae)

Extraction of the fresh leaves of Breynia coronata has yielded the Securinega alkaloids viroallosecurinine (4) and ent-phyllanthidine (6).

The alkaloids of Margaritaria indica. Part 2. The structures of 4-epiphyllanthine, margaritarine and the structural revision of securinol A

Extraction of the bark of Margaritaria indica has yielded the new alkaloids (4α)-4-methoxysecurinan-11-one 3 and 3-{N-[(2α,15α)-14,15-dihydro-11-oxosecurinan-15-yl]-2-aminoethyl}-1H-indole 10. Their structures followed from their spectroscopic properties. High field NMR spectra for the known Securinega alkaloids (4β)-4-methoxysecurinan-11-one 2 and (2α,4α)-4-methoxysecurinan-11-one 5 were recorded and interpreted. The structure of the known alkaloid securinol A is revised to 17 as a result of an X-ray crystal structure determination of its hydrobromide.

X-Ray crystal and molecular structure of nirurine, a novel alkaloid related to the securinega alkaloid skeleton, from Phyllanthus niruri(Euphorbiaceae)

Nirurine, an alkaloid from the aerial parts of Phyllanthus niruri L. (Euphorbiaceae), was shown by single-crystal X-ray crystallography to possess the structure (2). Through extensive decoupling experiments a complete n.m.r. assignment of all of the protons and carbons in nirurine has been achieved.

Studies directed toward the total synthesis of securinega alkaloids

A partir de prolinate d'ethyle et de thiopheneacetylacetate-2 de methyle, synthese d'hexahydro methano-5,10 thieno [3,2-d] pyrrolo [1,2-a] azepinol-10 dont on etudie quelques reactions

Biosynthesis of the Securinega alkaloids. Investigations of the early and late stages of the pathway

Feeding experiments with Securinega suffruticosa have established that tyrosine is a specific precursor of the alkaloid securinine. Additional experiments show that tyrosine is incorporated into securinine with loss of the 3- pro-S hydrogen atom of the amino acid and that neither 4′-hydroxy-2-phenylethanol nor 4′-hydroxyphenylacetic acid serves as a securinine precursor. Investigation of the metabolic relationship between securinine and dihydrosecurinine has shown that the former alkaloid is the precursor of the latter.

Biosynthesis of the Securinega alkaloids. Stereospecificity of hydrogen loss from C-3 of tyrosine

Specimens of (3RS)-[3-3H, 3-14C]-, (3R)-[3-3H, 3-14C]-, and (3S)-[3-3H, 3-14C]-DL-tyrosine have been administered to Securinega suffruticosa to demonstrate that the pro-S hydrogen at C-3 of tyrosine is lost during the biosynthesis of securinine from this amino-acid.