Die Stereochemie der Irone

The 6 R configuration of (+)-cis-γ-irone [(+)- 4 ] was established by chemical correlation with (—)-camphor. (+)-cis-γ-irone [(+)- 4 ] was converted into (+)-cis-α-irone [(+)- 1 ], (?)-trans-α-irone [(minus;;)- 2 ], and (+)-β-irone [(+)- 3 ], which therefore also have the 6 R configuration. The 2 S configurations of (+)-cis-α-irone [(+)- 1 ] and (+)-trans-α-irone [(+)- 2 ] were determined by comparison of their circular dichroism with that of R-α-ionone [(+)- 5 ]. The 2 S configuration of (+)-cis-γ-irone [(+)- 4 ] was established by chemical correlation with (+)-cis-α-irone [(+)- 1 ].     

Synthesis of(+)-(2S, 6S)-trans-α-Irone and of(-)-(2S, 6S)-trans-γ-Irone

A 3:1 mixture of (+)-(2S, 6S)-trans-α-irone ((+)-1) and (?)-(2S, 6S)-trans-γ-irone (?)-2) has been synthesized with ca. 70% e. e. by the ene reaction of (?)-(S)-3 and but-3-yn-2-one.     

Synthesis of asymmetric cyclopropyl acids and amines

(+) (S)- and (?) (R)-trans-1,2-cyclopropanedicarboxylic acids (C3A), (+) (S)- and (?) (R)-trans-1,2-diaminocyclopropanes (C3B), (+) (S)- and (?) (R)-trans-2-phenylcyclopropylamines (øC3B), (+) (S)- and (?) (R)-trans-1,2-bis(methylamino)-cyclopropanes (C3MB), and (+) (S)- and (?) (R)-trans-(2-phenylcyclopropyl)-methylamines (øC3MB) were prepared.     

Isocalamenenes from the Liverwort Bazzania tridens

Four new sesquiterpenoids, 1,4-trans-6-hydroxyisocalamenene; 1,4-trans-6-methoxyisocalamenene; (+)-aristol-9-en- 12β-ol, and eudesm-4(15)-en-6β-acetoxy-7β-ol, were isolated from Bazzania tridens, a liverwort species. Their structures were identified by means of spectroscopic methods. The two isocalamenenes are derived from a methyl rearrangement of the calamenene skeleton.     

The Constituents of Cananga odorata

Sixteen compounds, (+)-ushinsunine-β-N-oxide ( 1 ), cleistopholine ( 2 ), liriodenine ( 3 ), (-)-anonaine ( 4 ), (+)-nornuciferine ( 5 ), (+)-N-acetylnornuciferine ( 6 ), (-)-ushinsunine ( 7 ), (-)-norushinsunine ( 8 ), (-)-asimilobine ( 9 ), (+)-reticuline ( 10 ), N-trans-feruloyltyramine ( 11 ), β-sitosterol (12) and stigmasterol ( 13 ), lyscamine ( 14 ), (-)-anaxagoreine ( 15 ) and trans-cinnamic acid ( 16 ) were isolated from the methanolic extract of the Cananga odorata. Among them, 1 is a new stereoisomer of ushinsunine-β-N-oxide. The structures of these compounds were established by means of spectral experiments.     

Lignans and Kauranes from the Stems of Annona cherimola

Four lignans and six kauranes, (+)-epi-syringaresinol ( 1 ), annocherin A (16β-hydroxy-17,19-diacetoxy-ent-kaurane) ( 2 ), (+)-syringaresinol ( 3 ), (+)-dia-syringaresinol ( 4 ), liriodendrin[(+)-syringaresinol-di-O-β-D-glucopyranoside] ( 5 ), 16α-hydro-17-acetoxy-ent-kauran-19-oic acid ( 6 ), 16β-hydro-17-hydroxy-ent-kauran-19-al ( 7 ), 16α-hydro-17-hydroxy-ent-kauran-19-al ( 8 ), 16β-hydro-17-hydroxy-ent-kauran-19-oic acid ( 9 ) and 16α-hydro-17-hydroxy-ent-kauran-19-oic acid ( 10 ) were isolated from the stems of Annona cherimola. Among them, 1 is obtained for the first time from natural sources and 2 is a new compound. The structures of these compounds were characterized and identified by spectral analyses.     

The Constituents from the Stems of Annona cherimola

Thirty-five compounds including twenty-one alkaloids, lysicamine ( 1 ), liriodenine ( 2 ), atherospermidine ( 3 ), oxoxylopine ( 4 ), oxoanolobine ( 5 ), oxoglaucine ( 6 ), (-)-anonaine ( 7 ), (-)-asimilobine ( 8 ), (-)-xylopine ( 9 ), (-)-anolobine ( 10 ), (-)-norisocorydine ( 11 ), (+)-laurotetanine ( 12 ), (+)-isocorydine ( 13 ), (-)-N-methylasimilobine ( 14 ), (+)-N-methyllaurotetanine ( 15 ), (-)-norushinsunine ( 16 ), (-)-ushinsunine ( 17 ), (-)-N-formylanonaine ( 18 ), (+)-stepharine ( 19 ), (+)-orentaline ( 20 ), and (-)-kikemanine ( 21 ); four kauranes, ent-kaur-16-en-19-oic acid ( 22 ), 16β-hydroxy-17-acetoxy-ent-kauran-19-al ( 23 ), 17-acetoxy-16β-ent-kauran-19-oic acid ( 24 ), and 16β-hydroxy-17-acetoxy-ent-kauran-19-oic acid ( 25 ); two amides, N-trans-femloyltyramine ( 26 ), and N-trans-caffeoyltyramine ( 27 ); one purine, adenosine ( 28 ); one lactam amide, squamolone ( 29 ); and six steroids, β-sitosterol ( 30 ), stigmasterol ( 31 ), β-sitostenone ( 32 ), stigmasta-4,22-dien-3-one ( 33 ), 6β-hydroxy-β-sitosterone ( 34 ), and 6β-hydroxystigmasterone ( 35 ) are isolated from the stems of Annona cherimola. These compounds were characterized and identified by physical and spectral evidence. Among them, (-)-norisocorydine (11) was elucidated as a new enantiomer with a levorotary configuration, which is isolated for the first time.     

Biosynthese der Verrucarine und Roridine. Teil 5. Synthese von zwei Diastereoisomerenpaaren des [1,8-14C]-α-Bisabolols und Versuche zu deren Einbau in Verrucarol Verrucarine und Roridine, 32. Mitteilung [1]

The diastereoisomeric (+)-[1,8-¹⁴C]-(1'R,6R, S)-α-bisabolol ( 2a ) and (?)-[1,8-¹⁴C]-(1′S, 6R, S)-α-bisabolol ( 2b ) were synthesized by reaction of the Grignard compound of [1,6-¹⁴C]-5-bromo-2-methyl-2-pentene ( 12 ) with (+)-(R)- and (?)-(S)-4-acetyl-1-methyl-1-cyclohexene, ( 6a ) and ( 6b ) respectively. For the preparation of compound 12, cyclopropyl methyl ketone was treated with [¹⁴C]-methyl magnesium iodide to form the carbinol 11, which was cleaved by HBr. Compounds 6a and 6b were synthesized from (+)-(R)- and (?)-(S)-limonene, ( 4a ) and ( 4b ), via the derivatives 5a , 6a and 5b , 6b respectively. - This synthesis established the absolute configuration at C(1′) of the natural α-bisabolols: (R) for (+)-α-bisabolol and (S) for (?)-α-bisabolol. - Feeding experiments with cultures of Myrothecium roridum and radioactive (+)-(1′R, 6R, S)- and (?)-(1′S, 6R, S)-α-bisabolol ( 2a ) and ( 2b ) gave negative results. These findings indicate that bisabolane derivatives are not intermediates in the biosynthesis of verrucarol (3).     

Agnatasterone A and B,Unusual Pregnane Steroids Isolated from the North-East Atlantic Sponge Axinella agnata

Two novel pregnatrienolones isolated in very small amounts from the North-East-Atlantic demosponge Axinella agnata (Tetractinomorpha, Axinellida) are unique in having C(2)?C(3) (or C(3)?C(4)), C(7)?C(8), and C(16)?C(17) bonds and a 12β-OH group which, being strongly H-bonded to a 20-keto group, resists acylation. ¹H- and ¹³C-NMR spectroscopy of the steroids and of products of their selective epoxidation or reduction allow us to propose the structures (+)-12β-hydroxy-5α-pregna-2,7,16-trien-20-one ( = agnatasterone A, (+)- 1 ), and (+)-12β-hydroxy-5α-pregna-3,7,16-trien-20-one ( = agnatasterone B. (+)- 5 ), for the two steroids with minimal recourse to model compounds.     

Proof of the Absolute Configuration of (−)-(S)-2-Hydroxy-β-ionone by correlation with ursolic acid and with (−)-trans-verbenol

(?)-(S)-2-Hydroxy-β-ionone ( 33 ), (+)-(2 S, 6 S)-2-hydroxy-α-ionone ( 34 ), and their acetates 35 and 36 have been synthesized from (+)-(S)-6-methylbicyclo [4.3.0]-non-1-ene-3, 7-dione ( 3 ). The key intermediate (+)-(1 R, 3 S, 6 S)-2, 2, 6-trimethyl-7-oxobicyclo [4.3.0]non-3-yl acetate ( 7 ) was correlated with a degradation product of the pentacyclic triterpene ursolic acid ( 16 ). Compound 33 was also synthesized by an alternative route starting from (?)-trans-verbenol ( 42 ).     

Two new eudesman-4α-ol epoxides from the stem essential oil of Laggera pterodonta from Côte d’Ivoire

Abstract

The investigation of the stem essential oil of Laggera pterodonta (DC.) Sch. Bip. ex Oliv. (Asteraceae) from Côte d’Ivoire was carried out, using a combination of chromatographic (GC-RI, CC, pc-GC) and spectroscopic (GC-MS, ¹³C NMR) techniques. This study led to the identification of fifty constituents of which two new natural compounds 7β,11β-epoxy-eudesman-4α-ol and 7α,11α-epoxy-eudesman-4α-ol. Their structures were elucidated by 1?D and 2?D NMR spectroscopy after pc-GC purifying. Finally, 98.9% of the whole composition of the oil was identified with a high amount of 2,5-dimethoxy-p-cymene (78.9%). The other significant components were α-humulene (6.2%), (E)-β-caryophyllene (1.7%), thymyl methyl oxide (1.7%), α-phellandrene (1.5%), p-cymene (1.2%), (3αH,4βH,6αH,1αMe)-1,6-epoxy-3-hydroxycarvotanacetone angelic acid ester (1.1%) and 10-epi-γ-eudesmol (1.0%).     

New Triterpenes from the Heartwood of Melaleuca leucadendron L.

Fourteen chemical constituents were isolated from the CHCl₃ soluble portion of the heartwood of Melaleuca leucadendron L. These compounds include β-sitosterol (1) , β-sitostenone (2) , 6-hydroxy-4,6-dimethyl-3-hepten-2-one (3) , naphthalene (4) , squalene (5) , 2α3β-dihydroxyurs-12-en-28-oic acid (6) , 3β-hydroxylup-20(29)-en-27,28-dioic acid (7) , 2α,3β-dihydroxyolean-12-en-28-oic acid (8) , 3β,23-dihydroxyolean-12-en-28-oic acid (9) , 2α,3β,23-trihydroxyolean-12-en-28-oic acid (10) , 3β-trans-p-coumaroyloxy-2α,23-dihydroxyolean-12-en-28-oic acid (11) , and three novel oleanane derivatives 23-trans-p-coumaroyloxy-2α,3β-dihydroxyotean-12-en-28-oic acid (12), 3β-trans-caffeoyloxy-2α,23-dihydroxyolean-12-en-28-oic acid (13) , and its isomer 3β-cis-caffeoyloxy-2α,23-dihydroxyolean-12-en-28-oic acid (14) , The three novel compounds were characterized as the two and three O-methylated derivatives, respectively.     

Preparation and Absolute Configuration of Some Iris Essential Oil Constituents of the 5-methylsafranic-acid series

The β-dienoate (+)-(5S)- 13a (86% ee; meaning of α and β as in α- and β-irone, resp.) was obtained from (?)-(5S)- 9a via acid-catalyzed dehydration of the diastereoisomer mixture of allylic tertiary alcohols (+)-(1S,5S)- 15 /(+)-(1R,5S)- 15 (Scheme 3). Prolonged treatment gave clean isomerization via a [1,5]-H shift to the α-isomer (?)-(R)- 16a with only slight racemization (76% ee; Scheme 4). In contrast, the SnCl₄-catalyzed stereospecific cyclization of (+)-(Z)- 6 to (?)-trans- 8a (Scheme 2), followed by a diastereoselective epoxidation to (+)- 11 gave, via acid-catalyzed dehydration of the intermediate allylic secondary alcohol (?)- 12 , the same ester (+)- 13a (Scheme 3), but with poor optical purity (13% ee), due to an initial rapid [1,2]-H shift. The absolute configuration of (?)- 16a–c was confirmed by chemical correlation with (?)-trans- 19 (Scheme 4). ¹³C-NMR Assignments and absolute configurations of the intermediate esters, acids, aldehydes, and alcohols are presented.     

Synthese und Chiralität der stereoisomeren Achillene,Achillenole und Hymentherene

(+)-cis-Achillene ( 10 ) and (?)-trans-achillenol (7), two monoterpenes recently isolated [1] from the essential oil of Achilleafilipendulina, were synthesized, together with their stereoisomers (?)-(9) and (+)-(8), starting from (S)-(+)-2,6-trans-dimethylocta-1,3, 7-triene ( 1 ). The isomeric ß-hymen thereties ((?)- 3 and (+)-4), often quoted [2] [3] [4] but never isolated, were obtained as intermediates. The mode of synthesis chosen establishesis (R)-chirality for naturally occurring (?)-trans-achillenol (7) and (+)-cis-achillene ( 10 ) as well as for the purely synthetic 4, 7-diene derivatives described in this paper.     

Circulardichroismus. 62. Mitteilung. Chiroptische Eigenschaften einiger Trimethylcyclohexen-Derivate: Die Jonone,Irone und Abszisinsäuren

The absolute configuration of (+)-α-ionone 3 (R), the absolute configurations at C(6) of (+)-cis-α-irone 5 (6S) and (?)-trans-α-irone 6 (6R), and the absolute configurations of (+)-cis-abscisic acid 10 (S) and (+)-trans-abscisic acid 11 (S) are deduced from the CD.-spectra.     

Preparation of optically active flowery and woody-like odorant ketones via Corey-Chaykovsky oxiranylation: Irones and analogues

α-, β-, and γ-Irones and analogues have been prepared from optically active ketones (+)- 1 , (+)- 6a,b , and (+)- 17 , via a Corey-Chaykovsky oxiranylation (Me₂S, Me₂SO₄, Me₂SO, NaOH) followed by isomerisation (SnCl₄ or MgBr₂). (+)-Dihydrocyclocitral ( 19a ), obtained from (?)-citronellal, and analogue (+)- 19b , were condensed with various ketones to afford (+)- 21a–f , and after hydrogenation (+)- 22a–f. A mild oxidative degradation of aldehydes (+)-trans-and (?)-cis- 8a,b , to ketones (?)- 16a,b , as well as olfactive evaluations, ¹³C-NMR assignments, and absolute configurations of the intermediate epoxides, aldehydes, and alcohols are presented.     

Über die absolute Konfiguration der Visnagane

(+)-cis-Khellactone methyl ether ( 4 ) and (?)-trans-khellactone methyl ether ( 6 ) had earlier been assigned the absolute configurations 3′-S; 4′-S and 3′-S; 4′-R, respectively, on the basis of the FREUDENBERG , rule. Both compounds together with their defunctionalised derivatives (?)- 7 and (+)- 8 (=(+)-lomatin), obtained from a mixture of (+)-visnadin ( 1 ) and (+)-samidin ( 2 ), were investigated by the HOREAU method. A conformational analytical study showed that the optical yield should rise in the order 4 < 6 < 7 , 8. This order was found and the α-phenylbutyric acid liberated was always dextrorotatory. The centre 3′ of the khellactones and their derivatives must be R-chiral and not S. Treatment of (?)- 6 with pyridinium perbromide gave (?)-trans-3-bromokhellactone methyl ether ( 11 ) as orthorhombic crystals. The X-ray crystal structure determination was made using the anomalous scattering of the Mo-K α radiation by Br. The result, — centre 3′ R-chiral (fig. g) — showed that the HOREAU method was correct.     

Diterpenoide Drüsenfarbstoffe aus Labiaten: Coleone U,V, W und 14-O-Formyl-coleon-V sowie 2 Royleanone aus Plectranthus myrianthus BRIQ.; cis- und trans-A/B-6, 7-Dioxoroyleanon

Leaf-gland Pigments: Coleons U, V, W, 14- O -Formyl-coleon-V, and two Royleanones from Plectranthus myrianthus BRIQ. ; cis - and trans -A/B-6,7-Dioxoroyleanones From leaf-glands of the South-African P. myrianthus (Labiatae) the following diterpenoids have been isolated and their structures established: coleon U, C₂₀H₂₆O₅ (6, 11, 12, 14-tetrahydroxy-abieta-5, 8, 11, 13-tetraene-7-one, 2a ); coleon V, C₂₀H₂₆O₅ (11, 12, 14-trihydroxy-abieta-8, 11, 13-triene-6, 7-dione, 4a ); coleon W, C₂₂H₂₈O₈ (16(or 17)-acetoxy-6, 11, 12, 14, 17 (or 16)-pentahydroxy-abieta-5, 8, 11, 13-tetraene-7-one, 6 ); 14-O-formyl-coleon-V, C₂₁H₂₆O₆ (14-formyloxy-11, 12-dihydroxy-abieta-8, 11, 13-triene-6, 7-dione, 4b ); 7α-formyloxy-6β-hydroxyroyleanone, C₂₁H₂₈O₆ (7α-formyloxy-6β, 12-dihydroxy-abieta-8, 12-diene-11, 14-dione, 1a ); the already known 6β, 7α-dihydroxyroyleanone ( 1c ) and a dimeric abietane derivative whose structure is not yet elucidated. This is the first record of a co-occurrence of coleons and royleanones in the same plant. In the course of chemical investigations of 4a and 4b the highly oxidized trans- and cis-A/B-6,7-dioxoroyleanones ( 5a and 5b ) were obtained.     

Analogues of α‐Campholenal (= (1R)‐2,2,3‐Trimethylcyclopent‐3‐ene‐1‐acetaldehyde) as Building Blocks for (+)‐β‐Necrodol (= (1S,3S)‐2,2,3‐Trimethyl‐4‐methylenecyclopentanemethanol) and Sandalwood‐like Alcohols

To complete our panorama in structure–activity relationships (SARs) of sandalwood‐like alcohols derived from analogues of α‐campholenal (= (1R)‐2,2,3‐trimethylcyclopent‐3‐ene‐1‐acetaldehyde), we isomerized the epoxy‐isopropyl‐apopinene (?)‐ 2d to the corresponding unreported α‐campholenal analogue (+)‐ 4d (Scheme 1). Derived from the known 3‐demethyl‐α‐campholenal (+)‐ 4a , we prepared the saturated analogue (+)‐ 5a by hydrogenation, while the heterocyclic aldehyde (+)‐ 5b was obtained via a Bayer‐Villiger reaction from the known methyl ketone (+)‐ 6 . Oxidative hydroboration of the known α‐campholenal acetal (?)‐ 8b allowed, after subsequent oxidation of alcohol (+)‐ 9b to ketone (+)‐ 10 , and appropriate alkyl Grignard reaction, access to the 3,4‐disubstituted analogues (+)‐ 4f,g following dehydration and deprotection. (Scheme 2). Epoxidation of either (+)‐ 4b or its methyl ketone (+)‐ 4h , afforded stereoselectively the trans‐epoxy derivatives 11a,b , while the minor cis‐stereoisomer (+)‐ 12a was isolated by chromatography (trans/cis of the epoxy moiety relative to the C₂ or C₃ side chain). Alternatively, the corresponding trans‐epoxy alcohol or acetate 13a,b was obtained either by reduction/esterification from trans‐epoxy aldehyde (+)‐ 11a or by stereoselective epoxidation of the α‐campholenol (+)‐ 15a or of its acetate (?)‐ 15b , respectively. Their cis‐analogues were prepared starting from (+)‐ 12a . Either (+)‐ 4h or (?)‐ 11b , was submitted to a Bayer‐Villiger oxidation to afford acetate (?)‐ 16a . Since isomerizations of (?)‐ 16 lead preferentially to β‐campholene isomers, we followed a known procedure for the isomerization of (?)‐epoxyverbenone (?)‐ 2e to the norcampholenal analogue (+)‐ 19a . Reduction and subsequent protection afforded the silyl ether (?)‐ 19c , which was stereoselectively hydroborated under oxidative condition to afford the secondary alcohol (+)‐ 20c . Further oxidation and epimerization furnished the trans‐ketone (?)‐ 17a , a known intermediate of either (+)‐β‐necrodol (= (+)‐(1S,3S)‐2,2,3‐trimethyl‐4‐methylenecyclopentanemethanol; 17c ) or (+)‐(Z)‐lancifolol (= (1S,3R,4Z)‐2,2,3‐trimethyl‐4‐(4‐methylpent‐3‐enylidene)cyclopentanemethanol). Finally, hydrogenation of (+)‐ 4b gave the saturated cis‐aldehyde (+)‐ 21 , readily reduced to its corresponding alcohol (+)‐ 22a . Similarly, hydrogenation of β‐campholenol (= 2,3,3‐trimethylcyclopent‐1‐ene‐1‐ethanol) gave access via the cis‐alcohol rac‐ 23a , to the cis‐aldehyde rac‐ 24 .     

Contribution à la phytochimie du genre Gentiana. XXV. Etude des composés flavoniques et xanthoniques dans les feuilles de Gentiana X marcailhouana RY. Nouveaux cinnamoyl-C-glucosides flavoniques

Phytochemistry of genus Gentiana XXV: Study of the flavonic and xanthonic compounds in leaves of Gentiana X marcailhouana RY . New cinnamoyl-C-glucosyl-flavones Nine flavonic compounds: isoorientin ( 1 ), isovitexin ( 2 ), isoorientin-4′-O-β-D -glucoside ( 3 ), isovitexin-4′-O-β-D -glucoside ( 4 ), luteolin-7-O-β-D -glucoside ( 5 ), trans-cafeoyl-2′′-isoorientin ( 6 ), trans-feruloyl-2′′-isoorientin ( 7 ), trans-p-coumaroyl-2′′-isoorientin ( 8 ), p-O-β-D -glucosyl-trans-cafeoyl-2′′-isoorientin ( 9 ) and three xanthones: gentioside ( 10 ), isogentisine ( 11 ), mangiferin ( 12 ), have been identified from leaves of Gentiana X marcailhouana RY . Compounds 8 and 9 were described for the first time. The cyclitol L -(+)-bornesitol ( 13 ) has been also isolated.