Juan Zinczuk

Vibrational study of tolazoline hydrochloride by using FTIR-Raman and DFT calculations

Quantum mechanical (QM) calculations have been carried out in order to study the tolazoline hydrochloride theoretical structure and vibrational properties. This compound was characterized by infrared and Raman spectroscopies in the solid phase. For a complete assignment of the IR and Raman spectra, the density functional theory (DFT) calculations were combined with Pulays Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical frequency values to the experimental ones. An agreement between theoretical and available experimental results was found. Three intense bands in the infrared spectrum characteristic of the protonated species of the compound were detected. Also, the possible charge-transfer and the topological properties for both benzyl and imidazoline rings were studied by means of Natural Bond Orbital (NBO) and Atoms in Molecules theory (AIM) investigation.

Enantioselective syntheses and resolution of the key white intermediate for the synthesis of trisporic acids

Abstract Two asymmetric syntheses of the alkylated cyclohexenone carboxylic acid moiety, the key White intermediate ( 4a ), of trisporic acids A, B and C are described. The syntheses feature a Michael addition in tandem with an aldol condensation as the central step. The resolution of this readily available intermediate is also described.

Resolution and absolute configuration of a tricyclic lactone. A potentially useful precursor of highly functionalized terpenoids

Abstract The highly functionalized tricyclic lactone 1 was obtained in optically pure form by the sulfoximine-mediated resolution of the enone methyl acetal 3. The absolute configuration of (−)-3 and consequently of (+)-1, was determined by the transformation of (−)-3 into (−)-5, a known intermediate in the total synthesis of forskolin (2) and confirmed by application of the high field FT NMR Mosher method to alcohol 6.

An efficient and environmentally benign chemical synthesis of testolactone

A comparative study of two approaches for the chemical synthesis of the biologically interesting steroid testolactone is described. The first approach is efficient but classical, in the second one, hazardous chemicals were replaced by benign alternatives maintaining the same degree of efficiency.

Detours en route to a total synthesis of (+)-cassiol

Abstract A synthesis of the antiulcerogenic compound (+)-cassiol 1b has been achieved in 43% yield starting with lactol ( S )- 2 and sulfone 26 . This short and efficient synthesis features the one-pot Julia olefination reaction of the sodium anion of ( S )- 2 with 26 , through the key intermediate (−)- 9 . This synthesis has been developed as a result of exploratory experiments including different olefination reactions on 2 . An attempt to synthesize the intermediate 9 by an intramolecular aldol condensation approach of the open chain precursor 4 is also described.

A concise synthesis of (+)-cassiol

Abstract A synthesis of the anti-ulcerogenic compound (+)-cassiol 1b with 43% overall yield has been achieved. This short and efficient synthesis features the one-pot Julia olefination reaction of lactol ( S )- 2 with sulfone 3b through the key intermediate (−)- 4b .

(N-methylphenylsulfoximidoyl]methyllithium: A versatile reagent for the determination of absolute configuration of six-membered ring ketones

Abstract The diastereotopic chemical shift differences of the 1 H and 13 C NMR signals of the adducts formed by addition of ( N -methylphenylsulfoximidoyl)methyllithium ( 2 ) to cyclic ketones has been studied. The stereodifferentiation of the proton and carbon atoms follow a very regular pattern and the rule that can be drawn provides an alternative and complementary method to earlier procedures for the determination of absolute configuration of six-membered ring ketones.

Potential antitumoral properties of a new copper complex with santonic acid.

A new copper(II) complex of santonic acid [Cu(2)(sant)(4)(H(2)O)(2)].2(1/2)H(2)O has been prepared and characterized by electronic, vibrational, EPR spectral studies, and stability determinations in solution. The presence of two antiferrromagnetically coupled copper centers in the solid state was detected by EPR. The dinuclear Cu(II) complex crystallizes in the tetragonal P4(3)2(1)2 space group, with a=b=14.498(3), c=64.07(1)A. Biological studies indicate that the complex displays interesting potential antitumoral actions.

Studies directed toward the preparation of key intermediates for the synthesis of trisporic acids and cassiol

An enantioselective synthesis and resolution of the key White intermediate (3) for the synthesis of trisporic acids are described. Attempts to develop a synthetic route toward the antiulcerogenic compound cassiol (2) by an olefination reaction of 3 and an alternative sequence involving a Michael addition followed by an aldol condensation of an open substrate, are also reported.

THE MICHAEL-ALDOL CONDENSATION APPROACH TO THE CONSTRUCTION OF KEY INTERMEDIATES IN THE SYNTHESIS OF TERPENOID NATURAL PRODUCTS

Short routes for the preparation of highly oxygenated decalines, key intermediates for the synthesis of nimbolide m, by a sequence involving a Michael addition followed by an aldol condensation, are described. Many terpenoid products possessing a variety of structures were isolated from Azadirachta indica Juss. (Meliaceae), the Indias famed neem tree.1 Of this large group of natural products, azadirachtin (lJ has received increasing attention from a synthetic point of view due to its remarkable insecticidal properties.2 More recently, two structurally less complex tetranortriterpenoids, nimbolide (a and 28deoxonimbolide a), showing promising biological activity were also isolated from this interesting plant.3