bluuebunny/crossref_metadata_2025_split huggingface dataset:
The gene for ribosomal protein eL12′ from artemia and the genes for ribosomal proteins in yeast share common sequences at their 5′‐ends
Authors: Maassen J. A. , Schop E. N. 
Published: September 2010

AbstractWe have isolated and characterized genomic clones for the ribosomal protein eL12′ from the brine shrimp Artemia. The gene consists of 5 exons spanning a region of more than 11 kilobases on the Artemia genome. DNA sequencing of the region upstream from the transcription initiation point shows the presence of sequence elements that are similar to sequences specific for yeast ribosomal protein genes. This finding suggests a common mechanism for the regulation of ribosomal protein gene expression in eukaryotes.
Di‐n‐alkyl‐(N‐ligand)palladium(II) complexes. Thermolysis and reactions with olefins
Authors: Sustmann Reiner , Lau Jürgen , Zipp Manfred 
Published: September 2010

Abstract(2,2′‐Bipyridine)diethylpalladium(II) reacts with electron‐deficient olefins (methyl acrylate, acrylonitrile, dimethyl fumarate, dimethyl maleate, maleic anhydride, fumaronitrile and tetracyano‐ethylene) to produce, with the exception of acrylonitrile, almost exclusively n‐butane as the product of reductive elimination. Apart from methyl acrylate and acrylonitrile, organometallic reaction products, (2,2′‐bipyridine)olefinpalladium(0) complexes, are isolated. The temperature dependence of the 1H NMR and 13C NMR spectra of the fumaronitrile complex demonstrates reversible dissociation of the olefin. The thermolysis of the diethylpalladium complexes with 4,4′‐dimethyl‐2,2′‐bipyridine or o‐phenanthroline as ligands leads to no change in behaviour. (2,2′‐Bipyridine)di‐n‐propylpalladium shows, upon thermolysis, the same product distribution as does the diethyl complex, i.e. propane/propene in the absence of olefin and n‐hexane in the presence of tetracyanoethylene.
New functionalized 3,3‐dimethylcyclopropene derivatives and their rearrangement via vinylcarbene intermediates
Authors: Kirms Mark A. , Primke Hartmut , Stohlmeier Michael , de Meijere Armin 
Published: September 2010

AbstractThe 1‐(methylthio)‐substituted cyclopropenes 5a‐c and the corresponding tert‐butyl 1‐cyclopropenecarboxylate 10, which are easily prepared by electrophilic substitution of the protected monolithiated 3,3‐dimethylcyclopropenes 3a‐c, are reasonable stable at room temperature. Upon heating to 150°C, or under photolytic conditions, both 5a and 10 form allenes 8 and 11 exclusively. The first‐order kinetics of the rearrangement 3a→8 was determined as In (k) = 27.54 − 28040/(R.T).
Synthesis of 3‐alkoxy‐7,8‐didehydro‐4‐hydroxy‐N‐methylmorphinan‐6‐ones from morphine. Intermediates for novel A‐ and C‐ring‐functionalized morphinans. (Chemistry of opium alkaloids, Part XXII)
Authors: Brands K. M. J. , Lie T. S. , Maat L. 
Published: September 2010

AbstractCesium‐assisted benzylation of morphine (1) gave 3‐O‐benzylmorphine (3) in high yield, leading to a convenient synthesis of 3‐benzyloxy‐7,8‐didehydro‐4‐methoxy‐N‐methylmorphinan‐6‐one (8). This was accomplished by Oppenauer oxidation of 3, followed by 4,5α‐epoxy ring opening and methylation, respectively. The key step in this sequence, viz. the reductive epoxy ring opening with retention of the 7,8‐double bond, could also be applied to codeinone (4) giving quantitatively thebainone‐A (6). The low‐yield synthesis of 3 involving a classical procedure can be explained by the Hofmann degradation products 16 and 17.The morphinan‐5,7‐diene 14 was obtained from 8 via the p‐toluenesulfonylhydrazone 13. Morphinan‐6,8‐dienes are accessible from 8 using known procedures.
The synthesis and properties of 2,3,23(22),24‐tetrahydro‐21H‐biline‐1,19‐diones, model systems for biliprotein chromophores: 2,3,23(22),24‐tetrahydro‐17,18‐dimethyl‐21H‐biline‐1,19‐dione and its (4E)‐21‐methyl, (4Z + 4E)‐22‐methyl, (9Z + 9E)‐23‐methyl, (4E)‐21,22‐dimethyl and 21,22‐methylene homologues
Authors: Koek J. H. , Hoef K. v. D. , van Es J. J. G. S. , Lugtenburg J. , Fokkens R. 
Published: September 2010

AbstractThe title compounds (1, 2, 5, 6, 7, 13) have been synthesized from the correctly substituted 3,4‐dihydro‐2,2′‐pyrromethen‐5[1H]‐one (14a…e) and 5′‐formyl‐3,4‐dimethyl‐2,2′‐pyrromethen‐5[1H]‐one (15a…d) derivatives via acid‐catalyzed condensation and subsequent neutralization. Using 1H NMR spectroscopy, the configuration of the double bonds of each compound could be established. The systems, locked in only one of the possible tautomeric forms (22‐H or 23‐H), differ in wavelength with regard to the longest absorption maximum from 600 nm for 22N‐alkyl to 550 nm for 23N‐alkyl. The electronic spectra of 1 and 2 indicate that, for the systems liable to undergo 22‐23 proton tautomerization, the equilibrium is largely shifted to the side of the 23‐H form. The stabilization in the 23‐H tautomer is due to the direct interaction of the electron‐rich pyrrolidone ring with the electron‐poor azafulvene ring. The λmax value is only marginally dependent upon the conformation and configuration of the system. The ϵmax values, however, are highly sensitive to the overall conformation, with the helix‐type configuration showing the lower and the more extended systems the higher ϵmax values.The presence of the 2,3 single bond brings the pKb values into the physiological range, allowing the system to be protonated at pH ≈︁ 7. This means that, in biliproteins, the chromophore may occur in the neutral form or in the positive or negative ion form, each stabilized via the interaction with the peptide chain. At room temperature, the title compounds do not display fluorescence. At liquidnitrogen temperature, however, the model compounds, locked in one tautomer, are good fluorescers. The systems subject to proton tautomerization do not show fluorescence.
Spectroscopy and reactivity of zinc 20‐oxaporphyrin‐IX dimethyl ester
Authors: Hempenius M. A. , Koek J. H. , Lugtenburg J. , Fokkens R. 
Published: September 2010

AbstractA facile method of preparing zinc 20‐oxaprotoporphyrin‐IX dimethyl ester (1) from biliverdin‐IXα dimethyl ester has been found. According to NMR spectroscopy, the oxa substituent has a pronounced influence on the properties of the macrocyclic ring system. The 1H NMR spectrum reveals an aromatic structure and 13CNMR shows that in 1 a positive charge is delocalized, in agreement with the presence of one positive charge, and further that C‐1 and C‐19 have acquired the highest positive charge. This is corroborated by the reaction with nucleophiles, especially thiolates, leading to isolated adducts which could be well characterized. The adducts are the result of nucleophilic attack on the positions 1 and 19 exclusively, which agrees well with the charge on these positions in 1. The adducts show interesting spectroscopic properties. The study of oxaporphyrins and their nucleophilic adducts may contribute to a fuller understanding of the formation and properties of bile pigments.
Synthesis of fragments of the capsular polysaccharide of Haemophilus influenzae type b: Part I. Preparation of suitably protected 1‐O‐β‐D‐ribofuranosyl‐D‐ribitol building blocks
Authors: Hermans J. P. G. , Poot L. , van der Marel G. A. , Hoogerhout P. , Kloosterman M. , van Boom J. H. , van Boeckel C. A. A. , Evenberg D. , Poolman J. T. 
Published: September 2010

AbstractThe synthesis of the protected ribosylribitol derivatives 15 and 17, which are building blocks for the preparation of fragments of the H. influenzae type b polysaccharide, is presented. Starting from D‐ribonolactone (1), 5‐O‐allyl‐2,3,4‐tri‐O‐benzyl‐D‐ribitol (8) was prepared in seven steps (Scheme 1). Coupling of 8 with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranose (9) in the presence of trimethylsilyl trifluoromethanesulfonate gave the ribosylribitol derivative 10 (Scheme 2), which was debenzoylated to afford compound 11. The C‐3′‐ and C‐5′‐hydroxyl functions of the ribose moiety of 11 were protected with the 1,1,3,3‐tetraisopropyldisiloxane‐1,3‐diyl group and the C‐2′ position with the benzyloxymethyl group. Compound 13 thus obtained was converted into its 5‐O‐trans‐1‐propenyl isomer 14.Cleavage of the propenyl group from 14 gave compound 15, which can be phosphorylated at O‐5 of the ribitol. On the other hand, removal of the 3′,5′‐protection from 14 and subsequent blocking of the primary hydroxyl function yielded ribosylribitol derivative 17 having a 3′‐hydroxyl function available for phosphorylation.
A new approach to annelated butenolides. The total synthesis of (±)‐isodrimenin
Authors: Jansen B. J. M. , Peperzak R. M. , de Groot Ae. 
Published: September 2010

AbstractA new approach to annelated butenolides has been developed starting from trans‐5,5,8a‐trimethyl‐3,4,4a,5,6,7,8,8a‐octahydro‐1(2H)‐naphthalenone (3) and cyclohexanones. A reaction sequence consisting of formylation of the enolates of these ketones, protection of the formyl group as its dioxolane and addition of methoxy(phenylthio)methyllithium has been used to introduce the necessary functionalized carbon atoms. Rearrangement of the adducts to α‐(phenylthio)aldehydes, followed by hydrolysis of the dioxolane, resulted in the formation of butenolides. The method has been demonstrated in the total synthesis of (±)‐isodrimenin. Direct hydrolysis of the adducts, obtained after addition of methoxy(phenylthio)methyllithium, followed by treatment with acid, also gave butenolides.
Phosphorylation of allylic hydroxy groups via phosphite intermediates
Authors: Shadid B. R. , van der Plas H. C. , de Vroom E. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractPhosphitylation of an allylic hydroxy group with salicylchlorophosphite gives an allyl 1‐H‐phosphonate mono‐ester, which can be readily oxidized to the corresponding phosphate mono‐ester. Application of this phosphite‐triester approach was further demonstrated in the preparation of 1‐H‐phosphonate and phosphate mono‐esters of N‐protected trans‐zeatin.
Phosphorylation of benzyl‐protected sugar derivatives via 1‐H‐phosphonate intermediates: Synthesis of DL‐myo‐inositol 1,4,5‐tris‐1‐H‐phosphonate
Authors: Dreef C. E. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractThe crystalline and easily accessible ammonium salt of benzyl‐1‐H‐phosphonic acid has been used for the formation of intermediate benzyl‐1‐H‐phosphonate diester bonds between primary, secondary and anomerically HO‐groups of benzyl‐protected (pseudo)sugar derivatives. These intermediates proved to be very suitable for the preparation of modified and non‐modified phosphate functions.
A note on the use of porous silver silicates as promoter in carbohydrate coupling reactions
Authors: van Boeckel C. A. A. , Beetz T. , Kock‐van Dalen A. C. , van Bekkum H. 
Published: September 2010

AbstractDifferent insoluble silver salts were used to promote the β‐glycosidic bond formation between the aglycon methyl (2,3,4‐tri‐O‐benzyl‐α‐D‐glucopyranosyl bromide) uronate (1) and the aglycon 3‐O‐acetyl‐1,6‐anhydro‐2‐azido‐2‐deoxy‐D‐glucopyranose (2). The different promoters have different activity, but do not affect the β/α ratio (β/α = 1.5/1) of this coupling reaction. The most reactive promoter is Ag (I) on silica‐alumina with enhanced cation capacity.
Stereoselective synthesis of cis and trans four‐membered cyclic nitrones
Authors: van Eijk Peter J. S. S. , Overkempe Cor , Trompenaars Willem P. , Reinhoudt David N. , Manninen Lauri M. , van Hummel Gerrit J. , Harkema Sybolt 
Published: September 2010

AbstractNitroalkenes 3–5 react with ynamines (1‐aminoacetylenes) 6 to yield four‐membered cyclic nitrones (2,3‐dihydroazete 1‐oxides) 7–13. The nitroalkenes 3 and 5c give the cis fourmembered cyclic nitrones 7–11, whereas 4 and 5b yield the trans four‐membered cyclic nitrones 12–13 upon reaction with 6. Nitroalkene 4i reacts with 6c to give a 1:1 mixture of the cis and trans four‐membered cyclic nitrones 9g and 13i. The trans stereochemistry of trans‐N,N‐diethyl‐2, 3‐dihydro‐3‐(2‐methoxynaphthalenyl)‐2‐methyl‐4‐phenyl‐2‐azetecarboxamide 1‐oxide (13k) was elucidated by means of X‐ray analysis. Only from the reaction of 1‐nitrocyclopentene (5a) with 6c, the initially formed (4 + 2) cycloadduct, the nitronic ester 17 has been isolated. The thermal ring contraction of 17 yields 3a, 4, 5, 6‐tetrahydro‐N,N‐dimethyl‐3‐phenyl‐3H‐cyclopent[c]isoxazole‐3‐ carboxamide (19), the structure of which was established by X‐ray analysis. The trans four‐membered cyclic nitrones are thermally relatively stable compared with the cis nitrones. The mechanism of the stereoselective formation of the nitrones is related to the conformation of the (4 + 2) cycloadduct 16, which could be correlated with Chem‐X and MNDO calculations.
Micellar structure studied by 2D‐NMR
Authors: Nusselder Jan Jaap H. , Engberts Jan B. F. N. , Boelens Rolf , Kaptein Robert 
Published: September 2010

AbstractThis paper describes the possibility of using 2D‐NMR spectroscopy in the study of the morphology of micelles. In aqueous solution, the monomeric surfactant 1‐methyl‐4‐dodecylpyridinium iodide magnified image exhibits positive NOE's whereas negative NOE's are observed for the micellar aggregate. 1‐Methyl‐4‐n‐butylpyridinium iodide magnified image, which does not form micelles, only shows positive NOE's. It is argued that the observation of negative NOE's for micelles is reconcilable with quantitative data for the dynamics of these surfactant aggregates.
An improved synthesis of the antithyroid factor DL‐goitrin
Authors: Brandsma L. , Keegstra M. A. , Verkruijsse H. D. , Bos K. D. 
Published: September 2010

AbstractDL‐1‐Amino‐3‐buten‐2‐ol HH2CCH‐CH(OH)‐CH2NH2 has been synthesized in a satisfactory overall yield by reduction of the protected cyanohydrin H2CCH‐CH(OR)‐CN [R = ‐CH(CH3)OC2H5] with aluminum hydride, followed by removal of the protecting group with aqueous hydrochloric acid and treatment with potassium hydroxide. The amino alcohol is a key intermediate in a synthesis of the antithyroid factor goitrin reported previously.
Reactions of (μ‐PhPLi)2Fe2(CO)6 with metal halides
Authors: Seyferth Dietmar , Henderson Richard S. , Wood Timothy G. 
Published: September 2010

AbstractMetal carbonyl cluster complexes containing iron, phenylphosphido units and another metal (Ni, Pd, Pt, Co, Hg) have been prepared by reactions of (μ‐PhPLi)2Fe2(CO)6 with metal halides and (μ‐PhPH)2Fe2(CO)6 with zerovalent metal complexes.
Synthesis, IR and 119mSn Mössbauer spectra of di‐ and tri‐organotin molybdates
Authors: Smith Peter J. , Patel Bhagwati N. 
Published: September 2010

Abstract11 organotin molybdates, R2SnMoO4, where R = Me (1), Et (2), Bu (3) and Oct (4), (R3Sn)MoO4, where R = Bu (5), Ph (6), c‐C6H11 (7) and PhMe2CCH2 (8), and (R3Sn)(R′3Sn)MoO4, where R = Bu, R′ = Ph (9) or c‐C6H11 (10); R = Ph, R′ = c‐C6H11 (11), have been synthesised and their structures in the solid state investigated by 119mSn Mössbauer and IR spectroscopy. The Mössbauer spectra at 80 K are in accord with the tin atoms in the dialkyltin molybdates occupying a trans‐R2SnX4 octahedral geometry, and those in the bis(triorganotin) molybdates adopting a trans‐R3SnX2 trigonal bipyramidal stereochemistry, due to intermolecular bridging by the MoO4 ligands.The unsymmetrical bis(triorganotin) molybdates are the first examples of stable triorganotin compounds containing R3SnX and R′3SnX groups (X = electronegative radical) in the same molecule.
A nickel‐carbene complex as an intermediate in the polymerization of isocyanides
Authors: Kamer Paul C. J. , Nolte Roeland J. M. , Drenth Wiendelt 
Published: September 2010

AbstractAn intermediate in the polymerization of isocyanides, catalysed by nickel(II), has been isolated and characterized. The polymerization starts by nucleophilic attack of (S)‐(‐ )‐(1‐phenylethyl)amine on the terminal carbon atom of a coordinated isocyanide of tetrakis(tert‐butyl isocyanide)nickel(II) perchlorate. The resulting intermediate was isolated and shown to be a nickel‐carbene complex: Ni(CN‐t‐C4H9)3 [C[NHCH(CH3)C6H5]NH‐t‐C4H9](ClO4)2. In solution, the carbene complex appears to have three conformations. The effect of these conformations on the enantioselective polymerization of isocyanides is discussed.
The phthalation of 2‐amino‐2‐deoxy‐D‐glucose and N‐methyl‐1‐amino‐1‐deoxy‐D‐glucitol; conversion of the products to organotin derivatives. A ready migration of acetyl from oxygen to nitrogen under neutral conditions
Authors: Patel Atula , Poller Robert C. 
Published: September 2010

AbstractN‐Phthalation of 2‐amino‐2‐deoxy‐D‐glucose was followed by replacement of the acidic proton by tributyl‐ and triphenylstannyl groups. A similar reaction with 1‐(methylamino)‐1‐deoxy‐D‐glucitol failed and successive treatment with benzyl chloroformate and acetic anhydride followed by catalytic hydrogenation showed that a 1,4 O → N acetyl migration had occurred. Phthalation and stannylation succeeded under different conditions.
Les (triméthylsilyl)bicyclo[n.1.0]‐alcènes, nouveaux silylcyclopropanes bicycliques fonctionnels
Authors: Grignon‐Dubois M. , Dunoguès J. , Ahra M. 
Published: September 2010

AbstractNous proposons une méthode de synthèse de bicyclo[n.1.0]‐alcènes siliciés originaux, de mise en œuvre simple et rapide. Elle permet d'accéder dans de bonnes conditions aus deux isomères endo et exo monosiliciés ainsi qu'aux analogues gem‐disiliciés.Le comportement de ces dérivés vis‐á‐vis d'acides [HCl, (CH3COOH)2BF3] montre que la taille du grand cycle et la position relative de la double liaison par rapport au cyclopropane, détermine le site de l'attaque électrophile: selon les cas, elle intervient sur la double liaison ou sur le cycle á 3 chaînons. Ces résultats ouvrent des perspectives nouvelles pour la fonctionalisation des cyclènes via la cyclopropanation.
Palladium(0)‐catalyzed isomerization of α,β‐epoxy ketones to β‐diketones
Authors: Suzuki M. , Watanabe A. , Noyori R. 
Published: September 2010

AbstractIn the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium(0) and 1,2‐bis(diphenylphosphino)ethane, α,β‐epoxy ketones isomerize to the corresponding β‐diketones in high yields. Both open‐chain and cyclic substrates can be used. Possible reaction mechanisms are discussed.
Reactions of monoazadienes with metal carbonyl complexes.II. REACTIONS OF N‐ALKYL‐(E)‐CROTONALDIMINE WITH Ru3(CO)12. THE X‐RAY CRYSTAL STRUCTURE OF Ru3(CO)6(CH3‐CCH‐CHN‐C3H7‐i)2, AN ACYCLIC CLUSTER WHICH IS ISOLOBALLY RELATED TO RUTHENOCENE
Authors: Mul Wilhelmus P. , Elsevier Cornelis J. , Vrieze Kees , Smeets Wilberth J. J. , Spek Anthony L. 
Published: September 2010

AbstractThe reaction of Ru3(CO)12 with CH3‐CHCH‐CHN‐C3H7‐i in refluxing heptane yields RU3(CO)6(CH3‐CCH‐CHN‐C3H7‐i)2 in two stereoisomeric forms, together with several other products. One of the stereoisomers was purified. The X‐ray crystal structure shows an unprecedented bent trinuclear metal core with two metal‐metal bonds. The two γ‐metallated monoazadienyl ligands each donate 7e to the acyclic cluster.
Synthesis and conformation of 1‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil and 9‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine; two novel sugar‐methylated nucleoside analogues
Authors: Koole L. H. , Moody H. M. , Buck H. M. , Grouiller A. , Essadiq H. , Vial J.‐M. , Chattopadhyaya J. 
Published: September 2010

AbstractThe preparation and high‐resolution 1H NMR conformational analysis of the two novel nucleoside analogues, 1‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil (compound 1) and 9‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine (compound 2), are described. Compounds 1 and 2 show a pronounced preference for the north conformation of the sugar ring. The north conformation corresponds with a sterically favoured equatorial location of the methyl group. The C4′ ‐ C5′ conformation in 1 and 2 is predominantly γt (trans orientation of O5′ and C3′). The configuration at C3′ in 1 and 2 was corroborated via a one‐dimensional NOE experiment. The structure of compound 1 (originally assigned as having the C3′‐methyl group on the β‐face of the furanosyl moiety) is revised on the basis of these data.
Amine catalyzed ring opening of (2 + 2) cycloadducts derived from enamines of cyclic ketones and methyl propynoate
Authors: Egberink R. J. M. , Verboom W. , Benders P. H. , Reinhoudt D. N. , Harkema S. 
Published: September 2010

AbstractThe (2 + 2) cycloadducts 3, 6, 10 and 13, derived from pyrrolidine enamines of cyclic ketones and methyl propynoate 2, react, under the influence of pyrrolidine via the α‐[(1‐pyrrolidinyl)methylene]cycloalkeneacetates (Z)‐4, (Z)‐7, (Z)‐11 and (Z)‐14, to give the corresponding E isomers. The structure of (E)‐7 has been unequivocally established by X‐ray analysis. The formation of (E)‐4, (E)‐7, (E)‐11 and (E)‐14 can be explained by the sequence: Michael addition, elimination, conrotatory ring opening, followed by Z/E isomerization. In the cases involving a relatively slow reaction (10, 13) and, in addition, the presence of an excess of pyrrolidine, the enamines 9, 16 and the propenoate 12 could also be detected. The formation of 12 can be rationalized by a Michael addition of pyrrolidine to methyl propynoate (2), formed by a retro (2 + 2) cycloaddition.
Total synthesis of optically active myo‐inositol 1,4,5‐trisphosphate and myo‐inositol 1,3,4,5‐tetrakisphosphate
Authors: Dreef C. E. , Tuinman R. J. , Elie C. J. J. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractA convenient approach to the preparation of the title compounds illustrating selective protection, optical resolution and phosphorylation is presented.
Mechanism of electrooxidation of substituted phenols in aqueous solutions: Some podophyllotoxin derivatives as models
Authors: Zuman Peter , Holthuis Joost J. M. 
Published: September 2010

AbstractEtoposide (1) and teniposide (2) proved to be suitable models for oxidation of phenols, because radicals formed by the one‐electron oxidation of their phenolates do not dimerize. Mechanism (1)‐(6) indicates in which pH range the oxidation occurs in a single two‐electron step and in which in two one‐electron transfers. The phenolates are more easily oxidized than phenols. Due to a rapid formation of the phenolate ions at the electrode surface, its oxidation is preferred even at pH 3, about seven pH units below the pKa value. Phenoxenium ions formed in the two‐electron oxidation eliminate CH3O− ions and form ortho‐quinones.
Diels‐Alder reaction of 6‐demethoxy‐β‐dihydrothebaine with methyl vinyl ketone using microwave heating; preparation and pharmacology of 3‐hydroxy‐α,α, 17‐trimethyl‐6β,14β‐ethenomorphinan‐7β‐methanol, a novel deoxygenated diprenorphine analogue (chemistry of opium alkaloids, part XXV
Authors: Linders J.T.M. , Kokje J.P. , Overhand M. , Lie T.S. , Maat L. 
Published: September 2010

AbstractDiels‐Alder reaction of 6‐demethoxy‐β‐dihydrothebaine 6 with methyl vinyl ketone (3‐buten‐2‐one) yielded, in a 3:2 ratio, (+)‐7β‐acetyl‐3‐methoxy‐17‐methyl‐6β,14β‐ethenomorphinan‐4‐ol (7) and the novel (+)‐8β‐acetyl‐3‐methoxy‐17‐methyl‐6β,14β‐ethenomorphinan‐4‐ol (8). Performing the reaction in a microwave oven resulted in a faster and cleaner reaction. 1H NMR and mass spectra of 8 were studied and the structure was finally established by single‐crystal X‐ray analysis of its 4‐O‐phenyl ether 13. In contrast to thebaine and 6‐demethoxythebaine, the cyclo‐addition reaction of 6‐demethoxy‐β‐dihydrothebaine with methyl vinyl ketone occurred at the α‐face of the diene system.Ullmann reaction of 7 with bromobenzene, followed by Grignard reaction with methylmagnesium bromide and removal of the phenoxyl group using sodium in liquid ammonia, afforded the tertiary alcohol 11. O‐Demethylation of 11 by potassium hydroxide in boiling glycol, using microwave heating, afforded (+)‐3‐hydroxy‐α,α,17‐trimethyl‐6β,14β‐ethenomorphinan‐7β‐methanol 12. The structure of 12 was confirmed by 1H NMR and single‐crystal X‐ray analysis. Compound 12 showed morphine‐like activity in the PPQ assay.