A. S. Sadykov

A demonstration of aldehyde-lactol tautomerism in gossypol by1H and13C NMR spectroscopy

Conclusions1.The existence of a tautomeric equilibrium between the aldehyde and lactol forms gossypol has, for the first time, been demonstrated through NMR spectroscopy. In DMSO, gossypol exists primarily in the lactol form, and primarily in the aldehyde form in acids, bases, and inert solvents.2.The method of preparation of the ethers of this compound determines the form of the product obtained.

Alkaloids of Sophora alopecuroides

SummaryOn the basis of spectral characteristics and chemical transformations, a new alkaloid with the composition C15H22O2N2 isolated fromSophora alopecuroides has been assigned the most probable structure of 13,14-dehydrosophoridine N-oxide.

Chapter 5 Lupine Alkaloids

Publisher Summary This chapter describes 13 C-NMR spectroscopy of quinolizidine alkaloids, X-ray structural investigation of quinolizidine alkaloids, bicyclic quinolizidine alkaloids, tricyclic quinolizidine alkaloids, tetracyclic quinolizidine alkaloids of the sparteine group, tetracyclic alkaloids of the leontidine group, tetracyclic alkaloids of the aloperine group, and tetracyclic alkaloids of the matrine group. Quinolizidine alkaloids (lupine alkaloids) occur in the family Leguminosae, especially the subfamily Papilionaceae. 13 C-NMR spectroscopy of quinolizidine alkaloids is based on spectral parameters of quinolizidine and its derivatives, as well as various alkaloids containing a quinolizidine nucleus. High-resolution MS shows aloperine to be different from all known types of quinolizidine alkaloids by fragmentation. The nature of MS decay shows that sophorine is a quinolizidine alkaloid of the lupinine type. The IR spectrum suggests the presence of a trans -quinolizidine moiety and an —NH—CO— -group. Alkaloid esters on hydrolysis give the respective organic acids and hydroxylupanines. The structures of these alkaloids are established mainly by spectral methods.

The biosynthesis of the alkaloids of Goebelia pachycarpa

Summary1. Qualitative and quantitative compositions of the main alkaloids in five development phases of theGoebelia pachycarpa C. A. Mey. have been determined.2. The radioactivities of the alkaloids isolated after feeding the plant with assumed precursors -[2-14C] lysine and [1,5-14C] cadaverine — show that vigorous synthesis of alkaloids takes place in the flowering and budding periods.3. The results of an investigation of the oxidation products and of the alkaloids introduced and isolated after the feeding of plants with labelled matrine and labelled sophocarpine show that the alkaloids undergo interconversion without intramolecular changes.

Mass-spectrometric study of some cholinesterase substrates

ConclusionsThe fundamental directions of mass spectrometric decomposition of molecular ions of the complex esters of N-(β-hydroxyethyl) anabasine and cytisine are related to the homolytic rupture of the ethylene bridge between the amine and complex-ester portions of the molecule and the McLafferty rearrangement.

New esters of O-ethylalkylphosphonic acids

A number of new O-ethyl S-alkyl alkylthiophosphonates, O-ethyl O-lupinine alkylphosphonates, and N-[(O-ethylalkylphosphinyl)hydroxyethyl]anabasines was synthesized.

THE STRUCTURE OF REGALAMINE

SummaryOn the basis of UV, IR, NMR, and mass spectra and chemical transformations the structure of 11,12-dihydroxy-2-methoxy-1,12-epoxyhexahydrohomoproaporphine has been proposed for regalamine.

Nmr investigation of the spatial structure of quinolizidine alkaloids IV. Conformation of sophoridine in solution

SummaryOn the basis of PMR spectra at 100 and 300 MHz, the conformation of the molecule of the alkaloid sophoridine in solution has been determined as A/B-, A/C-, and C/D-trans, B/C-cis, with the “chair” conformation of rings A and D and the “boat” conformation of rings B and C.

A study of complex mixtures of natural substances by the defocusing and dadi methods. V. Steroid metabolites of the phytopathogenic fungusVerticillium dahliae

The mixture of steroid metabolites of the phytopathogenic fungusV. dahliae have been studied by high- and low-resolution mass spectrometry, metastable defocusing, and the direct analysis of daughter ions (DADI). On the basis of the analysis of the spectral results obtained for the mixtures themselves and for the products of their tosylation the presence in the samples studied of mixtures of β-sitosterol, stigmasterol, and cholesterol has been established. Probable structures have been proposed for the components of the mixture with m/z values of the molecular ions of 426, 424, and 412.

Syntheses and investigations based on aphyllinic acid

Conclusions1.We obtained 60 new derivatives of AA and studied their conformations.2.Reaction of the hydrochloride of AA and its nitroso derivative with amino alcohols results in cyclization with formation of aphylline.3.We proposed a method of selective splitting off of the nitroso groups in esters of the compounds being studied.4.Mass spectrographic fragmentation of the esters under study, depending on the location of the nuclei, occurs predominantly at the complex ester part and the side chain and also in the particles from the decomposition of the piperidine ring.