Stereochemical features of the structure of germacrane lactones and the applicability of Geissman's rule in this series

Stereochemical features of the structure of the germacrane lactones have been investigated. By correlating the circular dichroism and the results of x-ray structural analyses of the germacranolides with different types of linkage of the lactone ring it has been estabished that Geissman's rule is satisfied in the trans-trans-germacral(10), 4-dienolide series if the lactone ring has the S-conformation and the decadiene ring the chair-chair conformation in the C₆-trans-lactones and, correspondingly, the A and chair-chair conformations in the C₆-cis compounds. The decadiene ring has the boat-boat conformation if there is an exocyclic double bond at C₁₀ in the C₈-trans-germacrolides, and a positive Cotton effect (CE) is observed in the CD spectra in the 220 nm region and a negative one at 200 nm.Institute of Chemistry of Plant Substances Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 742–748, November–December, 1990.     

Circular dichroism of some chlorine-containing guaianolides

A study of the circular dichroism of chlorine-containing guainolides has shown that a negative Cotton effect in the 260-nm region correlates with the trans-linkage of the lactone ring in acroptilin, hyrcanin, chlorohyssopifolin B, elegin, and biebsanin. It has been established that this nature of the linkage does not change on relactonization and hydrogenation. A chloromethylene substituent at C₄ causes a bathochromic shift of the lactone Cotton effect.     

Circular dichroism of steroids with a lactone ring B. Brassinosteroids and compounds related to them

The circular dichroism spectra of steroids having the lactone group in ring B that is characteristic for brassinosteroids, and their isomers, have been studied. It has been shown that in the spectra of the isomeric B-homo-7-oxa-6-ketosteroids and B-homo-6-oxa-7-ketosteroids differences are observed in the sign of the Cotton effect of the n-* transition of the carboxy group, which can be used for proving their structures.Institute of Bioorganic Chemistry, Belorussian Academy of Sciences, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 76–82, January–February, 1992.     

Influence of structure on the circular dichroism of methyl-substituted 1,3,4-tetrahydrobenz[b]azepin-2-ones

The chirooptical properties of methyl-substituted 1,3,4,5-tetrahydrobenz[b]azepin-2-ones have been studied. A considerable increase in the intensity of the Cotton effect (CE) in the 240–250 nm region with an enlargement of the lactam ring has been observed. The sign of this CE for seven-membered benzolactams correlates with the type of conformation of the lactam ring. A change in the nature of the conjugation (passage from lactams of the benzamide type -C₆H₄-CO-NH- to lactams of the anilide type -C₆H₄-NH-CO-) leads to an inversion of the signs of the CEs in the 230–250-nm region.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 97–100, January, 1984.     

Chiroptical properties of steroid 1,3-diaxial diols in the presence of [Mo2(OAc)4]

Summary Bidentate complexes of dimolybdenum tetraacetate with 1,3-diaxial diols show Cotton effects around 490–540 nm (CD band I), 400–440 nm (II), 350–380 nm (III), 320 nm (IV) and 280 nm (V). The sign of the Cotton effect II can be predicted by a proposed sector rule. It seems that from the Cotton effects for cyclic 1,3-diols the absolute configurations or conformations can be obtained.A part of this material was presented at III-rd International Conference on CD Spectroscopy [1]     

Circular dichroism of some carotanes

The circular dichroism method has been used to study the stereochemistry of the carotanes. An analysis of the results obtained has shown that an -oriented ester group at C₆ corresponds to a positive Cotton effect (CE) in the 240–260-nm region. A link has been established between the position of the carbonyl group in the ring B and the sign of a CE in the 340-nm region. Hydrolysis of an ester group at C₆ takes place more readily in an alkaline medium than in an acid medium, and in the case of carbonyl-containing carotanes dehydration takes place as well as hydrolysis.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 45–48, January–February, 1984.     

Stereochemical features of the structure of germacrane lactones and the applicability of Geissman's rule in this series

Stereochemical features of the structure of the germacrane lactones have been investigated. By correlating the circular dichroism and the results of x-ray structural analyses of the germacranolides with different types of linkage of the lactone ring it has been estabished that Geissman's rule is satisfied in the trans-trans-germacral(10), 4-dienolide series if the lactone ring has the S-conformation and the decadiene ring the chair-chair conformation in the C₆-trans-lactones and, correspondingly, the A and chair-chair conformations in the C₆-cis compounds. The decadiene ring has the boat-boat conformation if there is an exocyclic double bond at C₁₀ in the C₈-trans-germacrolides, and a positive Cotton effect (CE) is observed in the CD spectra in the 220 nm region and a negative one at 200 nm. Institute of Chemistry of Plant Substances Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 742–748, November–December, 1990.     

Sesquiterpenes of the roots of Inula grandis

Summary The roots ofInula grandis Schrenk has yielded a sesquiterpene lactone C₁₅H₂₀O₃, mp 134–135°C and 270°C, which has been called igalin, and two diols — C₁₅H₂₆O₂ with mp 102–102.5°C and C₁₅H₂₈O₅ with mp 320°C — which have been called igalol and grandol, respectively.Igalol is identical with the diol obtained by the reduction of igalan with sodium borohydride, and has the structure elemane-8,12-diol.The sesquiterpene hydroxy lactone lactone No. 8 has been isolated in the form of an oil and it is now being studied.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 17–20, January, 1971.     

The structure of a sesquiterpene lactone from Artemisia fragrans

Summary From the epigeal part ofArtemisia fragrans Willd. a new sesquiterpene lactone C₁₅H₂₀O₄ has been isolated which has been called alkhanin.It has been shown that alkhanin has the structure (I).V. L. Komarov Institute of Botany, Academy of Sciences of the Azerbaidzhan SSR, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–77, January–February, 1978.     

Structure of fegolide

A chloroform extract of the seeds ofFerula penninervis Rgl et Schmahl has yielded a new sesquiterpene lactone of the guaiane type — fegolide: C₂₀H₂₈O₅, mp 165–166°C []_D –150°C (c 0.17; chloroform).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 335–337, May–June, 1985.     

Investigation of the compositions and structures of the components of lactone C12H22O2 — the side product of the condensation of n-butyl alcohol

It was established by gas-liquid chromatography (GLC) that lactone C₁₂H₂₂O₂ consists of three components. Two components, which are its isomers, were isolated by rectification and also by means of preparative GLC. A racemic mixture of optical isomers of 2,4-diethyl-3-n-propylpentanedioic acid was isolated from the products of potassium permanganate oxidation of the salts of the hydroxy acids obtained from the isolated lactone isomers in one case, whereas the meso form of this acid was isolated in another case. On the basis of this, it was concluded that one lactone isomer, constituting 60–70% of the mixture, is 2,4_trans-diethyl-3_cis-n-propyl-5-pentanolide or 2,4_trans-diethyl-3_trans-n-propyl-5-pentanolide, and the other isomer, constituting 20–30% of the mixture, is 2,4_cis-diethyl-3_cis-n-propyl-5-pentanolide or 2,4_cis-diethyl-3-_trans-n-Propyl-5-Pentanolide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1174–1179, September, 1975.     

Structure of ferulide

The structure of a new sesquiterpene lactone — ferulide fromFerula penninervis Regel et Schmalh — has been established on the basis of its spectral characteristics. This compound has the composition C₂₀H₂₄O₅, mp 135–137°C.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 240–242, March–April, 1987.     

Triterpene glycosides ofAstragalus and their genins. XXI. Circular dichroism of cycloartane ketones

The CD spectra of a number of natural and synthetic cycloartane ketones have been studied. The influence of 6-hydroxy group on the Cotton effect due to a 3-keto function has been found. The Cotton effect has been determined for 6-oxo-and 11-oxocycloartanes.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 614–628, September–October, 1986.     

An isomer of coronopilin

Conclusions From the racemes ofC. xanthifolia Fresen. have been isolated a sesquiterpene lactone C₁₆H₂₀O₄, the structural (+)-isomer of (–)-coronopilin, which has not been studied previously; structure I has been proposed for it.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 5, pp. 375–377, 1969     

Higher Nuclearity Rhenium Halide Clusters That Contain Re–Re Multiple Bonds

The discovery that the rhenium chloride cluster Re₃Cl₉ and its chloro-anion [Re₃Cl₁₂]^3- contain a triangular cluster of Re atoms and Re–Re bond orders of two was first reported in 1963. This led very quickly to the report by F. A. Cotton of the first species with a metal–metal quadruple bond, namely, the [Re₂Cl₈]^2- anion. While the field of dinuclear multiple bond chemistry has undergone explosive growth in the last 40 years, that involving the chemistry of higher nuclearity clusters with metal–metal multiple bonds is much more limited. One of the relatively few exceptions is encountered with the aforementioned rhenium halides that contain the triangular [Re₃]⁹⁺ core. In the present review, the synthesis, structures and reactivity of these halide clusters and those of higher nuclearity that contain Re–Re multiple bonds are surveyed. This article provides a comprehensive review of the literature covering the 40 year period 1963–2003.     

A sesquiterpene lactone badkhysinin from the roots ofFerula oopoda

Summary A sesquiterpene lactone with the composition C₂₀H₂₄O₅, mp 104°–105° C, []_D –212.4° C (alcohol) has been isolated from the roots ofFerula oopoda Boiss. and has been called badkhysinin. Badkhysinin is an ester of angelic acid and an epoxyhydroxylactone C₁₅H₁₈O₄ with mp 185°–186° C apparently related to guaianolide with a hydrocarbon skeleton of irregular structure. A number of possible structural formulas for badkhysinin are given.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 2, pp. 93–99, 1966     

A new component ofArtemesia hanseniana

A sesquiterpene lactone with mp 97–99°C, C₁₅H₂₀O₃, identified as deoxy--santonin, has been isolated from the epigeal part ofArtemisia hanseniana var.phylostachus.V. L. Komarov Institute of Botany of the Academy of Sciences of the Azerbaidzhanian SSR, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 564–568, September–October, 1981.