Current status and prospects of development of the NAAPRO code

The paper contains a summary of the recent developments of the prediction part of the NAAPRO (Neutron Activation Analysis PRognosis and Optimization) code. Specific details are given for the activation product yield calculation approach used in the program and for the nuclear data libraries. The prospects for the code development are discussed.     

Raman-spectrum investigation of the equatorial and axial carbonyl groups of some substituted cyclohexanes

Summary In the determination of conformations in accordance with the largest substituents it is found that compound (IV) has the conformations trans-ee and trans-aa and compound (V) the conformations cis-ae and cis-ea; none of these conformations predominates substantially, as with neither of the two possible conformations of the compound (III).     

Use of the paramagnetic shift agent Eu(DPM)3 for studying the structure and stereochemistry of conferol and conferone

Summary A spectrophotometric method is proposed for determining the content of aspidin in a crystalline powder and in the rhizomes of the fernsDryopteris spinulosa (M),D. phegopteris (L.), andD. fragrans (L.) Schott.All-Union Scientific-Research Institute for Medicinal Plants. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 684–687, November–December, 1970.     

Further new rearranged lanostanoids from the seeds of Abies mariesii and A. firma

In addition to reported 17,14-friedo lanostane type (I) of triterpene further triterpenes having new rearranged lanostane skeletons, 17,13-friedo lanostane (II) and 8(14→13R) abeo-17,13-friedo lanostane (III), have been isolated from the seed of Abiesmariesii. The skeletons I and II were also found to occur in A. firma. Their structures have been elucidated by spectral and X-ray diffraction analyses.     

Oils of the seeds of Ziziphora pedicellata and Eremostachys molluceloides

Summary The fatty oils of the seeds of the wild speciesZiziphora pedicellata andEremostachys molluceloides (Labiatae) have been investigated. The glyceride, pigment, and hydrocarbon compositions of these oils and the fatty-acid composition of the oil ofZ. pedicellata have been determined.The oil ofE. molluceloides contains laballenic acid.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 324–328, May–June, 1975.     

The effect of sulfur and selenium substitutents on the regiochemistry of diels-alder reactions

2-Phenylthio-1,3-butadiene (1) and 2-phenylseleno-1,3-butadiene (2) have been generated in situ from their SO₂ adducts and reacted with a series of unsymmetrical dienophiles. The regiochemical results have been analyzed in terms of qualitative perturbation theory.     

Synthesis of the Oligosaccharide Moieties of Musettamycin,Marcellomycin and Aclacinomycin A,Antitumor Antibiotics

Abstract

Condensation of benzyl 2,3,6-trideoxy-3-trifluoroacetamido-α-L-lyxo-hexopyranoside (5) with 4-O-acetyl-3-O-benzyl-2,6-dideoxy-α-L-lyxo-hexopyranosyl bromide (10) carried out under Koenigs-Knorr conditions gave 12. Total deprotection of 12 and N-dimethylation at C-3 led to 17 while selective removal of the 4-O-acetyl group led to 13, a synthetic intermediate for preparing 24 and 33. Condensation of 13 with di-O-acetyl-L-fucal (18) or 4-O-acetyl-L-amicetal (25) in the presence of N-iodosuccinimide followed by hydrogenolysis of the C-2-I bond gave 20 and 27 respectively. The trisaccharide 24 then was obtained from 20 by the same sequence of reactions used to convert 12 into 17. After deacetylation and oxidation, this set of reactions also transformed 27 into 33.     

Saturated heterocycles 115: Cycloaddition of nitrilimine and nitrile oxide to norbornane- and norbornene-fused dihydro-1,3-oxazines

By cycloaddition of nitrilimine and nitrile oxide to diexo and diendo norbornane- and norbornene-fused structural isomeric dihydro-1,3-oxazlnes (1-3), tetracyclic 1,3-oxazino-1, 2,4-trlazolines (7-9) and 1,2,4-oxadiazolines (10-12) were obtained. With norbornehe dipolarophiles, which contain a C=N and a C=C bond, the cycloaddition takes place at the olefinic bond and the diexo compound 4 yields 13 regioselectively, whereas the diendo isomer 5 gives an Isomeric mixture of isoxazolines 14 and 15. From the diexo derivative 6, however, a bis-adduct 16 is formed. The stereostructures of the adducts have been elucidated by NMR spectroscopy.     

Aspects of tautomerism. Part 16. Influence of the y-keto function on the reactions of sulphonic acids

Reaction of sodium 2-formylbenzenesulphonate (1) with thionyl chloride or phosphorous pentachloride gives a mixture of pseudo (2) and normal (3) sulphonyl chlorides. Whereas ammonium 2-carboxybenzenesulphonate (6) gives only the normal sulphonyl chloride (7) on reaction with thionyl chloride, a mixture of normal (7) and pseudo (8) isomers are formed on reaction with phosphorous pentachloride. Sodium 2-benzoylbenzenesulphonate (15), on the other hand, gives the corresponding normal sulphonyl chloride (16) on reaction with both of the reagents mentioned above. Based on these observations it is concluded that γ-keto sulphonic acids are amenable to the influence of γ-carbonyl group as in the case of γ-keto carboxylic acids but to a lesser extent.     

Peptide ozonolysis: Product structures and relative reactivities for oxidation of tyrosine and histidine residues

Angiotensin II (DRVYIHPF) and two analogs, (DRVYIAPA and DRVAIHPA), were used as model systems to study the ozonolysis of peptides containing tyrosine and histidine residues. The ESI mass spectrum of angiotensin II following exposure to ozone showed the formation of adducts containing one, three, and four oxygen atoms. CID and SID spectra of these adducts were consistent with formation of Tyr+O and His+3O as expected from previous work with amino acids. However, several fragment ions observed in the CID and SID spectra suggested formation of a rather unexpected adduct, Tyr+3O, and a small amount of the Phe+O adduct. These findings were confirmed by examining two angiotensin analogs. Exposure of DRVYIAPA to ozone resulted in the addition of either one or three oxygen atoms on Tyr, while DRVAIHPA showed only the addition of three oxygen atoms—all on His. Other noteworthy minor oxidation products were observed from these analogs including Tyr+34 Da, His+5 Da, His+34 Da, and His+82 Da. The reaction rates of the peptides with ozone were found to be similar: second-order rate coefficients are 274 ± 3, 379 ± 6, and 439 ± 34 M⁻¹s⁻¹ for DRVYIAPA, DRVAIHPA, and angiotensin II, respectively. The relative rates indicate (1) an isolated His residue has a slightly greater ozone reactivity than an isolated Tyr residue, and (2) the reaction rates of isolated residues are not additive when both residues are present in the same molecule.     

Flavonoids, 40.+ Synthesis of 3-alkyl- and -arylthioflavanones and their transformations into sulfur-containing flavonoids

trans-3-Mesyloxyflavanones 1 were converted into cis- and trans-3-(alkylthio)- and -(phenylthio) flavanones 2-4 by nucleophilic substitution reaction with thiols or thiolates. Flavanones 2-4 were useful intermediates in the synthesis of various sulfur-containing derivatives; flavanones, flavones and dihydrochalcones possessing alkyl- or arylthio, -sulfinyl and -sulfonyl group. Oxidation of cis- and trans- isomers of 4 led to completely different products.     

A study of the oils of Ocimum basilicum and Cardaria repens

Summary The seed oils of the plantsOcimum basilicum andCardaria repens have been studied. Their physico-chemical properties and fatty acid and glyceride compositions have been determined. Both oils contain a hydroxy acid of undetermined structure. The oil ofOcimum basilicum contains an unusual trienic acid.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 7–11, January, 1971.     

Synthesis of Glycosyl Cyanides and C-Allyl Glycosides by the use of Glycosyl Fluoride Derivatives

A treatment of 2,3,5-tri-O-benzyl-B-D-ribofuranosyl fluoride (1) with cyanotrimethylsilane in the presence of boron trifluoride diethyl etherate gave 2,3,5-tri-O-benzyl-α- (2α) and -β-D-ribofuranosyl (2β) cyanide in 46.2% and 46.6% yields, respectively. Confirmation of the corresponding isocyano isomer (3) formation and its conversion into 2 under boron trifluoride catalysis at -78°C made it possible to deduce that both 2α and 2β were produced by way of 3 which was formed preponderantly in the initial stage of the reaction. On the other hand, the reaction of 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl fluoride (4) with cyanotrimethylsilane in diethyl ether by the use of boron trifluoride diethyl etherate (0.05 mol. equiv.) gave 2,3,4,6-tetra-O-benzyl-α -D-glucopyranosyl cyanide (5α), 2,3,4,6-tetra-O-benzyl-α- (6α), and -β-D-glucopyranosyl isocyanide (6β) as a 30:61:9 mixture (94% yield) but that in dichloromethane by the use of the catalyst (1.0 mol. equiv.) gave 5α (85% yield) as a sole product.

The reactions of 1 and of 4 with allyltrirnethylsilane under the same catalysis afforded C-allyl 2,3,5-tri-O-benzyl-α-D-ribofuranoside (7)(93.5% yield), and C-allyl 2,3,4,6-tetra-O-benzyl-α- (8α)(71.8% yield) and -β-D-glucopyranoside (8β) (22.4% yield), respectively.     

2H-Pyrrolo[3,4-b]pyridine and 2H-pyrrolo[3,4-c]pyridine: synthesis of the parent ring system and the Diels-Alder reaction

2H-Pyrrolo[3,4-b]pyridine (1) and 2H-pyrrolo[3,4-c]pyridine (2) were prepared and reacted with N-phenylmaleimide to give Diels-Alder adducts.     

On the Mechanism and Scope of a Novel Nitroolefin Rearrangement

D-Labelling permits differentiation between three plausible mechanistic pathways in the novel transformation of vinylaziridine 1 with β-nitrostyrene 4 to nitro enamino olefin 5. The results are consistent with a retro-ene reaction proceeding under mild conditions (80°). Choice of proper substituents can guide the reaction toward formation of azepines or substituted enamines.     

Synthesis of 3-methyl-coumarins, -thiacoumarins and -carbostyrils

Reaction of 3,6-dimethyl-4-phenyl-3,4-dihydrocoumarin5a with anhydrous aluminum chloride gave 3,6-dimethyl-coumarin (6a); likewise, 6-chloro-3-methyl-coumarin (6b) was obtained from5b. Substituted 3-methyl-thiacoumarins (8a,b and 3-methyl-carbostyrils (10a-e) were prepared from the reactions of the respectivea-methyl-cinnamoyl derivatives (7a,b and (9a-e), of thiophenols and anilines.     

Synthesis and structure of hexakis (p-hydroxyphenyloxy)benzene: A versatile analogue of the hydrogen-bonded hexameric unit of β-hydroquinone

The title hexaphenol (1), a direct analogue of the -hydroquinone hexameric unit, has been prepared by six-fold demethylation of hexakis (p-methoxyphenyloxy)benzene (2) with BBr₃. Host1 forms a trigonal adduct, space groupR3,a=22.088(3),c=12.232(3) Å, containing 6 molecules of pyridine per host molecule: a detailed X-ray study of this inclusion compound reveals a true clathrate structure, the closed cages of which accommodate a small, non-stoichiometric amount of water.     

SIMS and AES measurements on the LaNi5-hydrogen system

Summary SIMS (Secondary Ion Mass Spectrometry) and AES (Auger Electron Spectroscopy) investigations were carried out on polycrystalline LaNi₅ samples and on LaNi₅ samples, which have been loaded with hydrogen electrochemically. AES measurements show an enrichment of obviously oxidized La at the surface, while in the SIMS spectra the emission of negative ions attracts special attention. In contrast to the V-H- and Nb-H-system negative Me_xH_y-ions turned out to be the most sensitive species for hydrogen detection in SIMS experiments on LaNi₅. The emission of negative ions of type Ni_x and Ni_yH_x, which are not observed on pure Ni are due to the electropositive character of La in this special matrix and the presence of hydrogen. The results point to a higher affinity of hydrogen to Ni than to La.     

Alkaline degradation of the mycotoxin 4-deoxynivalenol

Treatment of the Fusarium trichothecene mycotoxin 4-deoxynivalenol (1) (DON)with aqueous NaOH at 75°C gave a mixture of three isomeric degradation products designated norDON-A (3a), norDON-B (4a) and norDON-C (5a). Structures and a mechanism for the formation of these products are proposed.     

Pentaketide metabolites of mutants and the biosynthesis of melanin inVerticillium tricorpus

From mutants of the fungusVerticillium tricorpus Isaac., having various genetic blocks in the biosynthesis of melanin, we have isolated and identified scytalone, flaviolin, 3,3-biflavinolin, 2-hydroxyjuglone, vermelone, and 1,8-dihydroxynaphthalene, which, in combination with the results of complementation analysis, has enabled the main stages of the biosynthesis of melanin inV. tricorpus to be established. The results on the inhibition of the biosynthesis of melanin by tricyclazole in natural isolates ofV. tricorpus indicates that the initital stages of the biosynthesis of melanin inV. tricorpus up to the formation of 1,3,8-trihydroxynaphthalene are identical with those ofVerticillium dahliae.V. I. Lenin State University, Tashkent. Division of General Genetics of the Cotton Plant, Academy of Sciences of the TadzhSSR, Dushanbe. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 486–492, July–August, 1985.