Rodrigo Rico

Isoquinoline alkaloids from Berberis Vulgaris subsp. Australis

Abstract Sixteen isoquinoline alkaloids were isolated from Berberis vulgaris subsp. australis . In addition to quaternary protoberberines and bisbenzylisoquinolines, a new seco - bis benzylisoquinoline, (-)-tejedine, is reported.

Ismine and related alkaloids from Lapiedra martinezii

Abstract Three phenantridine alkaloids have been isolated for the first time from natural sources ( Lapiedra martinezii ). Their structures suggest a biosynthetic relationships with ismine.

Alkaloid N-oxides of amaryllidaceae

Abstract Ungiminorine N -oxide was isolated from Pancratium maritimum , and homolycorine N -oxide and O -methyl lycorenine N -oxide from Lapiedra martinezii . These compounds represent the first examples of naturally occurring N -oxides from the Amaryllidaceae.

Synthesis of Homoprotoberberines and 8-Oxoprotoberberines by Sequential Bicyclization of Phenylacetamides

Abstract The reaction of phenylacetamides with oxalyl chloride/Lewis acid provides a convergent, high-yield entry to C-homoprotoberberine and 8-oxoprotoberberine alkaloids from available starting materials. This approach was used to synthesize 8-oxopseudopalmatine starting from N-[β-(3′,4′-dimethoxyphenyl)ethyl]-3,4-dimethoxyphenylacetamide. Some C-homoprotoberberines exhibit significant cytotoxicity against human breast carcinoma cells.

A new approach to the synthesis of 4,5-dioxoaporphine alkaloids from preformed biaryl bond precursors

Abstract The synthesis of cepharadione-B and 2-demethoxy analogues is described. Starting from fluorenones, ring C was formed by cyclization of (biphenyl-2-yl)acetyl morpholines under Bischler-Napieralsky conditions. The photochemistry of chloroacetamides was used to form ring B. The cytotoxicity of these compounds on several tumor cell lines was evaluated.

The Polonovski-Potier Reaction of Berbine N-Oxides. Synthesis of 8-Hydroxymethyl and 8-Methylberbines

Abstract The Polonovski–Potier reaction of trans and cis berbines N-oxides was studied. The 8-cyano derivative obtained from transN-oxides were used to synthesize 8-hydroxymethyl and 8-methyl berbines. This procedure was applied to the stereocontroled synthesis of (8R, 14S)-(−)-8-methylcanadine from (14S)-(−)-canadine.

Alkaloids from Fumaria sepium and Fumaria agraria

The plants of genus Fumaria L., which encompasses about 40 species (Southon and Buckingham, 1989), are annual herbs which have a wide distribution from India to Macaronesia. Twenty-two species are restricted to the Ibero-Mauritanian Region, which includes Algeria, Morocco and Spain (Liden, 1986). Plant material of Fumaria agraria Lag. (Fumariaceae) was collected from Churriana (Malaga, Spain) and that of Fumaria sepium Boiss. (Fumariaceae) from Los Barrios (Cadiz, Spain). Both were identified by the Department of Botany of the Faculty of Sciences of the University of Malaga. Voucher specimens (F. agraria MGC-23062 and, F. sepium MGC-31528) are deposited in the Faculty’s herbarium.

Surface characterization of di‐(2‐ethylhexyl)dithiophosphoric acid‐activated composite membranes by x‐ray photoelectron spectroscopy

Surface chemical characterization of a set of activated composite membranes containing different concentrations of di-(2-ethylhexyl)dithiophosphoric acid (DTPA) as carrier was performed by x-ray photoelectron spectroscopy (XPS). As a result of the addition of DTPA to the membrane samples, the N 1s signal intensities decrease, whereas the P 2p signal intensities increase with increasing carrier concentration. Upon acid addition, the polyamide component of the membrane was protonated and a new peak at higher binding energies was observed in the N 1s XPS signal, due to the increase of the positive charge of these protonated nitrogen atoms. The S 2p signals indicate the coexistence of two contributions assigned to the presence of the acid carrier ionically bonded to the protonated amide and to free acid molecules.

New amaryllidaceae alkaloids from Narcissus papyraceus Ker-Gawler

Three new alkaloids, O-methylpapyramine, O-methylmaritidine and 9-O-demethylhomolycorine N-oxide have been isolated from aerial parts of Narcissus papyraceus Ker-Gawler, together with lycorine, papyramine, pseudolycorine, homolycorine and 9-O-demethylhomolycorine

A versatile approach to the synthesis of 4,5-dioxoaporphine and 3,4-dioxocularine alkaloids. One-Pot sequential CB ring formation from arylacetamides

Abstract Cyclization of biarylacetamides to their phenanthrene derivatives is promoted by oxalyl chloride/stannyl chloride. The reaction proceeds with a second cyclization in which the oxalyl fragment acts as an α-dicarbonyl transfer agent to give 4,5-dioxoaporphine alkaloids in a single step. This double cyclization was also applied to aryloxyphenyl acetamides to give the corresponding 3,4-dioxocularine alkaloids. Decarbonylated aristocularine alkaloids were also formed in this case.