bluuebunny/crossref_metadata_2025 huggingface dataset:
Aromatic sulfonation 84. Sulfonation of bi‐ and tri‐phenylene
Authors: Cerfontain Hans , Laali Khosrow , Lambrechts Hans J. A.
Published: September 2010

The mono‐ and di‐sulfonation of biphenylene (1) and triphenylene (2) with SO3 in nitromethane as solvent at 0°C has been studied. The monosulfonation of both 1 and 2 leads exclusively to the formation of the 2‐sulfonic acid. In the case of 1, this results from the lower cation localization energy of the 2‐ as compared with the 1‐substitution; with 2, the substitution at the 1‐position is prevented by large steric hindrance. The sulfonation of biphenylene‐2‐sulfonic acid yields 65 % 2,6‐ and 35 % 2,7‐disulfonic acid, while that of triphenylene‐2‐sulfonic acid yields 59% 2,6‐, 1% 2,7‐ and 40% 2,11‐disulfonic acid. For both bi‐ and tri‐phenylene‐2‐sulfonic acid, the reactivity order of the sterically accessible positions in the non‐sulfo‐containing rings is governed by the (electronic) directing effect of the 2‐SO3H substituent.
The use of immobilized enzymes in organic synthesis. Part 6. Oxidation of 1‐alkyl‐3‐carbamoylpyridinium chlorides by rabbit liver aldehyde oxidase
Authors: Angelino S. A. G. F. , Buurman D. J. , van der Plas H. C. , Müller F.
Published: September 2010

A method is described for the oxidation of some 1‐alkyl‐3‐carbamoylpyridinium chlorides by reaction with immobilized rabbit liver aldehyde oxidase. With the 1‐methyl‐, 1‐ethyl‐and 1‐n‐propyl derivatives, only the 1‐alkyl‐1,6‐dihydro‐6‐oxo‐3‐pyridinecarboxamides have been obtained, but with the t‐Bu analogue the corresponding 4‐oxo compound was found as single product. The i‐Pr derivative gave rise to a mixture of the corresponding 4‐ and 6‐oxo compounds. From the kinetic data some information has been acquired with respect to the enzyme active‐site environment and the binding of the substrates to the enzyme.
A method for the determination of pyrite in coal
Authors: Kos C. H.
Published: September 2010

A rapid and simple method for the determination of pyrite in coal, based upon a two‐step extraction of iron from coal is presented. After milling the coal in a tungsten‐carbide vessel, the non‐pyritic iron is first removed and then the pyritic iron dissolved. This is then followed by AAS analysis. Analysis of pyritic sulfur and total iron in four types of coal demonstrate the reliability of this method.
Synthesis of DNA on a solid support by the hydroxybenzotriazole phosphotriester approach
Authors: Marugg J. E. , van der Morel G. A. , de Vroom E. , Bosch D. , van Boom J. H.
Published: September 2010

Application of the phosphorylating agent 2‐chlorophenyl‐0,0‐bis(1‐hydroxybenzotriazolyl)‐phosphate enabled us to synthesize DNA fragments (e.g., d‐AGGATCCT and d‐GTTCGG) on a polystyrene solid support:
On the luminescence of lanthanide decatungstates. III. Tetrabutylammonium and brucinium salts
Authors: Blasse G. , Zonnevijlle F.
Published: September 2010

The luminescence properties of the following decatungstates have been investigated: X9LnW10O36 (X = tetra‐n‐butylammonium or brucinium; Ln = Sm, Eu, Dy). Due to the large X ions, the separation between the lanthanide ions is very large. Consequently no interaction between these ions occurs, not even in the case of Sm and Dy. The tetra‐n‐butylammonium salts contain a small number of alkali metal ions. The emission of Eu3+ has been used to analyse the composition in more detail. The brucinium salts do not luminesce efficiently upon tungstate excitation, since the excitation energy is lost, for the greater part, in the brucinium ions.
Synthesis and structure of 6‐exo‐hydroxy‐1,2‐diphenyl‐1‐phosphoniatricyclo [3.3.1.1]decane iodide, a derivative of 1‐phosphaadamantane
Authors: Meeuwissen H. J. , Sirks G. , Bickelhaupt F. , Stam C. H. , Spek A. L.
Published: September 2010

The annelation reaction between l,2,3,6‐tetrahydro‐1‐phenyl‐4‐(1‐pyrrolidinyl)phosphorin 1‐oxide (10) and 2,2‐bis(chloromethyl)acetophenone (7) leads to two stereoisomeric 7‐benzoyl‐3‐phenyl‐3‐phosphabicyclo[3.3.1]nonan‐9‐one 3‐oxides 11a and 11b. Their difference resides in the configuration at phosphorus, which also determines the conformation of the bicyclononane skeleton, as revealed from the crystal structures. Reduction of the two keto functions in 11a with NaBH4 to give 12a, followed by HSiCl3 reduction to the phosphine 13a and acid‐catalyzed ring closure, yields the title compound (4a), the structure of which was corroborated by an X‐ray crystal structure determination. Interestingly, the same sequence of reactions converts 11b into a 3.3 : 1 mixture of 4a and 4b; presumably, inversion of configuration at phosphorus occurs in the last step and is catalyzed by acid.
The conversion of primary amines into nitrones: An extension of the Kröhnke reaction
Authors: Katritzky Alan R. , Dabbas Nadira , Patel Ranjan C. , Cozens Andrew J.
Published: September 2010

Primary amines react with 2‐(ethoxycarbonyl)‐4,6‐diphenylpyryliums to form pyridiniums. These are hydrolysed to 2‐carboxylatopyridiniums which react with p‐nitroso‐N,N‐dimethylaniline to give nitrones.
Réactivité comparée de germyléneamines, de digermylamines et de cyclogermazanes vis à vis de nitrones et d'oxaziridines isomères
Authors: Ère‐Baudet Monique Rivi , Rivière Pierre , Castel Annie , Lacrampe Georges , Satgé Jacques
Published: September 2010

L′addition de nitrones (R2C=NR′O) dans la liaison Ge‐N de germylamines acycliques (R3Ge)2NR′ conduit à des dérivés d'insertion dont la stabilité est discutée.

Les nitrones réagissent sur les germylèneamines (R2Ge=NR′) par cycloaddition dipolaire 1‐3 conduisant à des 1,3,5,2‐oxadiazagermolidines thermiquement instables. La décomposition de ces nouveaux hétérocycles conduit à l'imine carbonée correspondant à la germylèneamine de départ, au germoxane via la germanone transitoire et au nitrène correspondant à la nitrone.

La 2‐t‐butyl‐3‐phényloxaziridine conduit aux mêmes types de dérivés par ouverture de la liaison C‐O de cet hétérocycle.

Les réactions des cyclogermazanes sur les nitrones ne commencent qu'aux environs de 120°C et conduisent à des résultats semblables à ceux obtenus avec les germylèneamines. Il est montré qu'en présence de nucléophiles (Et3N, HMPT), ces réactions se produisent dès 70°C. Les nucléophiles semblent agir comme catalyseurs de dépolymérisation des cyclodigermazanes en germylèneamines.

Les mécanismes de formation et de décomposition des 1,3,5,2‐oxadiazagermolidines sont discutès.

La cycloaddition 1‐3 sur les nitrones apparaît comme une réaction de caractérisation chimique des germylèneamines.
Photochemical reactions of some aromatic thiones with bis(methylthio)ethyne; (4 + 2)‐ versus (2 + 2)‐cycloaddition products. Spectroscopic evidence for the equilibrium thiete ⇄ α,β‐unsaturated dithioester
Authors: Brouwer A. C. , Bos H. J. T.
Published: September 2010

Irradiation (λ > 525 nm) of the aromatic thiones 2 in the presence of bis(methylthio)‐ethyne 3 causes two cycloaddition reactions to occur between the photochemically excited thione 2 and the acetylene 3, as concluded from the isolated products. Compounds with structure 6 are believed to be products of a (4 + 2)‐cycloaddition reaction, whereas the formation of the isolated α,β‐unsaturated dithio esters 4 is rationalised on the basis of a (2 + 2)‐cycloaddition reaction. The preference for one reaction pathway over the other depends on the thione used and is discussed in terms of the structure of the thione 2. Spectroscopic observation of the equilibrium thiete 5 ⇄ α,β‐unsaturated dithio ester 4, in solution provides direct evidence for the (2 + 2)‐photocycloadducts, thietes 5.
The mean bond dissociation energy of the carbonmagnesium bond in bis(2,2‐dimethylpropyl)magnesium
Authors: Akkerman O. S. , Schat G. , Evers E. A. I. M. , Bickelhaupt F.
Published: September 2010

The standard enthalpy of formation of solid bis(2,2‐dimethylpropyl)magnesium (dineopentylmagnesium, Np2Mg) has been determined from its reaction enthalpy with aqueous hydrobromic acid and found to be ‐235.8 ± 5.5 kJ·mol−1. Using the experimentally determined sublimation enthalpy of Np2Mg and the enthalpies of formation of the 2,2‐dimethylpropyl radical and gaseous magnesium, the mean dissociation energy of the carbonmagnesium bond in the monomeric title compound is found to be 133.7 ± 5.0 kJ·mol−1. This value is discussed and compared with those of other reported carbonmagnesium bonds. In combination with the previously determined difference in enthalpy of formation of dimeric and monomeric Np2Mg, the bond energy of the bridging 2,2‐dimethylpropylmagnesium bonds in dimeric Np2Mg is calculated to be D̄B = 205 ± 3 kJ·mol−1, which is a remarkably high value.
Chemistry of ketene acetals VI. The influence of the dicyanoethene moiety on the reactivity and selectivity of β,β‐dicyano‐α,β‐unsaturated ketones in cycloadditions with ketene acetals
Authors: Bakker C. G. , Ooms P. H. M. , Scheeren J. W. , Nivard R. J. F.
Published: September 2010

The (2 + 2) versus (4 + 2) cycloadditions of two ketene acetals R1R2C=C(OMe)2 (R1 = R2 =OMe, 1a; R1 = H, R2 = Me, 1b) with several β, β‐dicyano‐α, β‐unsaturated ketones R3CO‐R4C=C(CN)2 (2a‐e, Table I) have been investigated. Cyclobutanes 3 were only obtained at room temperature in the cycloaddition of 2a (R3 = R4 = Ph) with 1b and 2d (R3, R4 = naphthyl) with 1a or 1b. In the latter case, an oxetane was obtained when ZnCl2 was used as a catalyst.

The thermodynamically more stable (4 + 2) cycloadducts were obtained at higher temperatures, except from 2e, in which the carbonyl group is part of an amide function. A high regiospecificity has been found in these cycloadditions. The influence of the dicyanoethene moiety on the cycloadditions is discussed and compared to analogous cycloadditions of 1a and 1b with α,β‐unsaturated ketones and α‐diketones.
Photochemistry of α,α,ω,ω‐tetramethyl‐1,2‐cycloalkanediones; influence of the conformation of the diketo moiety on the photochemical behaviour
Authors: Verheijdt Paul L. , Cerfontain Hans
Published: September 2010

A series of α,α,ω,ω‐tetramethyl‐1,2‐cycloalkanediones, with a ring size varying between 4 and 8 C atoms (la‐e), together with 2,2,5,5‐tetramethyl‐3,4‐hexanedione (2a), have been irradiated both in 2‐propanol and in benzene in order to study the influence of the diketo conformation on the photochemical behaviour of 1,2‐diketones. Irradiation of lb‐d in 2‐propanol leads exclusively to photoreduction with formation of the corresponding acyloins via intermolecular H abstraction, whereas le and 2 yield predominantly the 2‐hydroxycyclobutanone product via intramolecular H abstraction. The irradiations of la‐e in benzene lead to different products for the six homologous cyclic 1,2‐diketones. Mechanisms for the formation of the various products are proposed. It is concluded that the 1,2‐diketones with Φ (ground state) <90° and >90° react, upon excitation, from a conformation having a planar cisoid and transoid diketo geometry, respectively.
Photosubstitution and photoreduction of pyrene and 1‐halopyrenes
Authors: Tintel C. , Rietmeyer F. J. , Cornelisse J.
Published: September 2010

Upon irradiation, pyrene reacts with cyanide to give 1‐cyanopyrene and with amide to give 1‐aminopyrene. With oxygen nucleophiles no reaction takes place. Irradiation of pyrene in the presence of diethyl malonate anion yields 4,5,9,10‐tetrahydropyrene in high yield, probably via initial electron transfer to excited pyrene. 1‐Fluoropyrene can be photosubstituted with oxygen nucleophiles, leading to 1‐hydroxy‐ and 1‐methoxy‐pyrene, in contrast to 1‐chloro‐ and 1‐bromopyrene, which are converted into a mixture of pyrene and 4,5‐dihydropyrene upon irradiation.
A two‐step synthesis of benzo[e]pyrene via the pyrene dianion
Authors: Tintel C. , Lugtenburg J. , van Amsterdam G. A. J. , Erkelens C. , Cornelisse J.
Published: September 2010

Reaction of the pyrene dianion with 1,4‐diiodobutane afforded cis‐8b,9,10,11,12,12a‐hexahydrobenzo[e]pyrene, which could subsequently be oxidized by DDQ to give benzo[e]‐pyrene. Thus, benzo[e]pyrene was formed from pyrene in an overall yield of 46%.
The amination of halogeno‐2,7‐ and 1,8‐naphthyridines
Authors: van den Haak H. J. W. , van der Plas H. C.
Published: September 2010

The conversion of 1‐halogeno‐2,7‐naphthyridines into the corresponding 1‐amino compounds with KNH2/NH3, is shown, by the use of deuterated starting compounds, to proceed via an SN(AE)ipso substitution and not via an SN(AE)tele mechanism, even though convincing evidence for the formation of tele σ‐adduct, 8‐amino‐1‐halogeno‐dihydro‐2,7‐naphthyridinide, was obtained. Using the same methods, it is shown that the conversion of 2‐bromo‐1,8‐naphthyridine into 2‐amino‐1,8‐naphthyridine proceeds, to the extent of 40%, via an odd SN(AE)tele pathway.
Solutes in sulfuric acid. Part VIII. Protonation of phenol, 4‐fluorophenol and the 2‐ and 4‐sulfonates of anisole and phenol in concentrated aqueous sulfuric acid; determination of pKa values by means of 13C NMR
Authors: Koeberg‐Telder Ankie , Lambrechts Hans J. A. , Cerfontain Hans
Published: September 2010

The protonation of phenol (2), 4‐fluorophenol (3), phenyl methanesulfonate, potassium phenyl sulfate and the potassium 2‐ and ‐4‐sulfonates of both phenol and anisole in concentrated aqueous sulfuric acid at 30°C has been investigated using 13C NMR spectroscopy. The results show that phenol and 4‐fluorophenol are protonated predominantly on the oxygen atom. This protonation is governed by the H0a acidity function. The pKa of the oxonium ions of 2 and 3 are ‐6.40 ± 0.05 and ‐6.41 ± 0.05, respectively. The protonation of phenyl methanesulfonate occurs at acid concentrations > 100%. Potassium phenyl sulfate in ≥20% H2SO4 hydrolyses very rapidly to give phenol. The 2‐ and 4‐sulfonates of both phenol and anisole are protonated on both the ‐OR (R = H, Me) and the ‐SO3− groups; the sulfuric acid concentrations of half‐protonation have been determined to be between 80.0 and 83.3% H2SO4, corresponding with pKa's of the conjugate acids between ‐6.34 and ‐6.66 based on the H0a scale.
Photochemistry of dienones. Part 12. Photochemistry of (E)‐α‐ and (E)‐β‐damascone
Authors: Visser Cornelis P. , Cerfontain Hans
Published: September 2010

The photochemistry of (E)‐α‐ and (E)‐β‐damascone has been studied. Upon triplet‐sensitized irradiation, both compounds exclusively undergo (E)‐(Z) isomerization. (E)‐β‐damascone, upon direct irradiation with λ 254, 300 or 350 nm in non‐alcoholic solvents, exhibits only (E)‐(Z) isomerization. However, in an alcoholic solvent, direct irradiation induces cyclization and subsequent solvent incorporation, with formation of exo‐8‐alkoxy‐1,5,5‐endo‐9‐tetramethyl‐cis‐bicyclo[4.3.0]nonan‐7‐one (12).

(E)‐α‐damascone, upon direct irradiation, exhibits α‐cleavage with subsequent formation of the 1,3‐acyl shift product, and equal amounts of the dimerization products of the allylic radical, viz. 9 and 10. The 1,3‐acyl shift product again undergoes photo‐α‐cleavage and the only products, upon prolonged irradiation, are the bicyclohexenyls 9 and 10.
Synthesis of 10‐, 11‐, 19‐ and 20‐mono‐13C‐retinal
Authors: Pardoen J. A. , Neijenesch H. N. , Mulder P. P. J. , Lugtenburg J.
Published: September 2010

The 10‐, 11‐, 19‐ and 20‐mono‐13C‐all‐trans‐retinals were synthesized with >98% chemical purity and 92% 13C incorporation from 13C‐labelled acetonitrile and 13C‐labelled methyl iodide. Their 13C‐13C and 13C‐1H NMR coupling constants were measured.
Synthesis and properties of 2,3,17,18‐tetramethyl‐1,19‐[21H,24H]‐bilindione and 2,3,17,18,22,23‐hexamethyl‐23‐hydro‐1,19‐[21H,24H]‐bilindion‐10‐enium trifluoroacetate, two biliverdin model compounds
Authors: de Groot J. A. , van der Steen R. , Lugtenburg J.
Published: September 2010

The biliverdin model compound 1 could be prepared in high yield by acid‐catalyzed condensation of 3,4‐dimethyl‐2,2′‐pyrromethen‐5[1H]‐one (9) with the novel 3,4‐dimethyl‐5′–formyl‐2,2′‐pyrromethen‐5[1H]‐one (11). The biliverdinium model compound 3 could analogously be prepared quantitatively from 1′,3,4‐trimethyl‐2,2′‐pyrromethen‐5[1H]‐one (10) and 5′‐formyl‐1′,3,4‐trimethyl‐2,2′‐pyrromethen‐5[1H]‐one (12).

The analytical, chemical, photochemical and photophysical properties of these model compounds have been investigated. The data so obtained are compared with known aspects of the natural biliverdin compounds.
A new and convenient method for the amination of 1,6‐ and 1,7‐naphthyridines using potassium amide/liquid ammonia/potassium permanganate
Authors: Woźniak M. , van der Plas H. C. , Tomula M. , van Veldhuizen A.
Published: September 2010

Treatment of 3‐nitro‐1,6‐naphthyridine, its 2‐chloro‐, 2‐ethoxy‐ and 2‐amino derivatives, with liquid ammonia, containing potassium permanganate, gave the corresponding 2‐X‐4‐amino‐3‐nitro‐1,6‐naphthyridines (X = H, Cl, OEt, NH2). From 1H NMR spectroscopy sound evidence for the intermediacy of 2‐X‐4‐amino‐1,4‐dihydro‐3‐nitro‐1,6‐naphthyridine is obtained. Similarly, from 5,8‐dichloro(dibromo)‐1,7‐naphthyridine, the corresponding 2‐amino‐5,8‐dichloro‐(dibromo)‐1,7‐naphthyridines were formed on treatment with liquid ammonia/potassium amide/potassium permanganate. 1H NMR evidence for the intermediary C‐2 σ‐adduct has been obtained.
Ring transformations in reactions of heterocyclic compounds with nucleophiles. The conversion of 5‐nitropyrimidine into pyridine derivatives by CH‐acitve nitriles
Authors: Charushin Valery N. , van der Plas Henk C.
Published: September 2010

Nitriles R–CH2CN where R is CN, SO2C6H5, C6H4‐NO2‐p, C6H4‐CF3‐m, are effective reagents for converting 5‐nitropyrimidine (1) into 2‐amino‐5‐nitro‐3‐R‐pyridines (7). In reactions of 1 with cyanoacetic acid derivatives (methyl, ethyl, tert‐butyl esters), 3‐cyano‐5‐nitro–2(1H)‐pyridone is formed in addition to 7. Ketonic nitriles, such as 3‐oxobutyronitrile and 3‐oxo–3‐phenylpropionitrile, react with 1 to form 2‐methyl‐ and 2‐phenyl‐5‐nitro‐3‐cyanopyridine, respectively.

Plausible mechanisms are discussed. The reaction of 1 with N‐(cyanoacetyl)carbamate provides a facile synthetic route to 1,2,3,4‐tetrahydro‐6‐nitropyrido[2,3‐d]pyrimidine‐2,4‐dione.
Mono alkylation of γ,δ‐unsaturated β‐oxo esters via dianions. Part I
Authors: van den Goorbergh J. A. M. , van der Gen A.
Published: September 2010

γ,δ‐Unsaturated β‐oxo esters can be converted into their dianions 6 by reaction with 2 equivalents of lithium diisopropylamide (LDA). Reaction of these dianions with alkyl halides leads exclusively to mono‐γ‐alkylation and affords the unsaturated oxo esters 9 in good yields. Reaction with carbonyl compounds similarly affords the unsaturated δ‐hydroxy β‐oxo esters 10. The regiospecificity of these reactions is discussed in relation to the structure of the dianionic intermediates.
Base‐catalyzed carbon‐carbon bond formation reactions of ω‐hydroxylactams
Authors: Speckamp W. N. , de Boer J. J. J.
Published: September 2010

Active methylene compounds such as methyl ketones, 1,3‐dicarbonyl systems and nitromethane condense under the influence of base with ω‐hydroxylactams, thereby forming α‐alkylated nitrogen heterocycles. The ease of alkylation is determined by the position of a tautomeric equilibrium between ω‐hydroxylactam and the open‐chain amide‐aldehyde, which is dependent upon the type of N‐substituent and upon the lactam ring size. Some applications for the products obtained are indicated.
Enantioselectivity in the hydrolysis of esters catalyzed by polyelectrolyte surfactant complexes
Authors: Visser Hendrik G. J. , Nolte Roeland J. M. , Drenth Wiendelt
Published: September 2010

A cationic surfactant enhances the enantioselectivity of imidazole containing polymers of isocyanides in the hydrolysis of amino acid 4‐nitro‐phenyl esters.
Synthesis and analysis of tritiated neuropeptides
Authors: Kaspersen Frans M. , van Rooy Fons M. , Wallaart Jan , Funke Carel
Published: September 2010

The synthesis, purification and analysis of three tritiated neuropeptides are described. Org 2766 (an ACTH (4‐9) analogue) and Org GK 78 (des‐Tyr‐γ‐endorphin) were labelled in the aromatic ring of phenylalanine by catalytic deiodination of the (p‐iodophenyl)alanine precursors using 3H2.

Org 5878 (des‐enkephalin‐γ‐endorphin) was labelled in the lysine residue by reduction of the L‐2,6‐diamino‐4‐hexynoic acid‐containing analogue with 3H2. The peptides were purified by preparative HPLC using ammonium acetate buffer systems. The chemical purity was determined by 1H NMR, the radiochemical purity was measured by HPLC and the 3H distribution by 3H NMR. Specific activities (as determined by HPLC) were ca. 900 GBq mmol−1 for Org 2766 and Org GK 78 and 1400 GBq mmol−1 for Org 5878.
Syntheses and NMR analyses of deuterated mianserins
Authors: Kaspersen Frans M. , Favier J. S. , Wagenaars Gerard , Wallaart Jan , Funke Carel W.
Published: September 2010

Eleven deuterated analogues of mianserin have been synthesized and analyzed by 1H and 13C NMR. Based on these compounds, the aromatic part of the 1H spectrum of mianserin could be interpreted.
Synthesis of alkyloxazoline derivatives of 2‐amino‐2‐deoxy‐D‐glucopyranose via phosphate intermediates
Authors: Oltvoort J. J. , van Boeckel C. A. A. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Phosphorylation of 2‐(acylamino)‐3,4,6‐tri‐O‐acetyl‐2‐deoxy‐α/β‐D‐glucopyranose in the presence of triethylamine with 2‐chlorophenyl phosphorodi(1,2,4‐triazolide) gave 2‐alkyl(3,4,6‐tri‐O‐acetyl‐1,2‐dideoxy‐α‐D‐glucopyrano) [2,1 ‐d]‐2‐oxazolines.
Photochemical and Lewis‐acid‐catalyzed rearrangement of 1‐phenyl‐4‐methyl‐3,6‐dioxabicyclo[3.1.0]hexan‐2‐one into its tetronic acid isomer
Authors: Caus Maria J. , Cerfontain Hans , Piniella Juan F.
Published: September 2010

The irradiation of 2 in acetonitrile or methanol with λ 254 nm yields the tetronic acid derivative 3. The (thermal) BF3‐catalyzed rearrangement of 2 yields the same tetronic acid derivative. The structure of the tetronic acid 3 has been determined by means of X‐ray analysis; it forms monoclinic crystals with cell constants a = 10.868, b = 8.320, c = 20.936 Å and β = 90.65°. The space group is P21/n; in the unit cell there are eight molecules which exhibit intermolecular hydrogen bonding.
An approach to the synthesis of liponucleotides
Authors: Oltvoort J. J. , van der Marel G. A. , van Boeckel C. A. A. , van Boom J. H.
Published: September 2010

Phosphorylation of 3′‐O‐levulinoylthymidine*** using 2‐chlorophenyl bis‐O‐(1‐benzo‐triazolyl) phosphate, followed by addition of 1‐hexadecanol, afforded in high yield a fully protected triester derivative of thymidine.

Similarly, phosphorylation of 1,2‐di‐O‐palmitoyl‐sn‐glycerol with the same reagent and subsequent addition of the above thymidine derivative gave a triester derivative of thymidine in excellent yield. Both triester derivatives were efficiently converted into the corresponding liponucleotides by the removal of the 2‐chlorophenyl and levulinoyl protective groups.
Studies on the synthesis of the protected C‐terminal segment of vasoactive intestinal peptide (VIP) via its 28‐aspartic acid analogue
Authors: Schaaper W. M. M. , Voskamp D.
Published: September 2010

A major problem in the synthesis in solution of the gastrointestinal peptide VIP is the solubility of C‐terminal intermediates. Already in the tripeptide stage, the solubility in the usual solvents is very low and gives rise to low coupling yields. The C‐terminal asparagine amide, in combination with leucine and isoleucine, seems to play an important role in this phenomenon. We synthesized the protected C‐terminal segments, VIP(27‐28), VIP(22‐28) and VIP( 14‐28), via the temporary substitution of 28‐asparagine by a β‐tert‐butyl protected aspartic acid. This substitution resulted in a dramatic improvement in solubility. The synthesis could easily be performed via the repetitive excess mixed anhydride method. In the last stage of the synthesis, the β‐tert‐butyl protection of 28‐aspartic acid could be removed selectively. The deprotected aspartic acid was converted into asparagine by amidation using the mixed anhydride or the carbodiimide method.
Reactions of cisoid α‐methoxyimino ketones with N,N‐diethyl‐1‐propyn‐1‐amine. Formation of a γ‐methoxyimino α,β‐unsaturated carboxamide or a 1,4‐benzoxazine
Authors: Elferink V. H. M. , Bos H. J. T.
Published: September 2010

Addition of 2‐(methoxyimino)acenaphten‐1‐one 1 and 10‐(methoxyimino)phenanthren‐9‐one 3 to N,N‐diethyl‐1‐propyn‐1‐amine gives the γ‐methoxyimino α,β‐unsaturated carboxamides 2 and 4 via a (2 + 2)‐cycloaddition reaction with the carbonyl group, followed by an electrocyclic ring opening. Reaction of 4,6‐di‐tert‐butyl‐2‐(methoxyimino)‐3,5‐cyclohexadien‐1‐one 5 with N,N‐diethyl‐1‐propyn‐1‐amine gives rise to formation of 1,4‐benzoxazine 6, presumably via addition of the ynamine to the C = N group, followed by 1,3‐rearrangement of methoxide and subsequent ring closure of the 0CCNCC system.
Electrophilic additions to (dimethylamino)allene
Authors: Klop W. , Klusener P. A. A. , Brandsma L.
Published: September 2010

(Dimethylamino)allene reacts with alcohols, thiols and aliphatic secondary amines without the addition of a catalyst to give the adducts H2C=CH−C(Y)NMe2 (Y = OR, SR or NR2). The reactions are slowed down or do not proceed if bases (KOH, t‐BuOK) are present. Under the influence of H⊕ (H2O, NH4Cl or acid alumina), the adducts rearrange to the enamines Y‐CH2CH=CH−NMe2 (100% trans). If Y = SR or NR2, the enamines are obtained in good yields, but with Y = OR, the rearrangement proceeds much more slowly and cannot be forced to completion without formation of resinous material.
Deuterium isotope effects in mianserin
Authors: Kaspersen Frans M. , van Acquoy Jan , van de Laar Gerrit L. M. , Wagenaars Gerard N. , Funke Carel W.
Published: September 2010

Isotopic fractionation in HPLC can be observed for mianserin when deuterated in the piperazine ring, except on position 14b. This isotope effect is caused by an increase in basicity upon introduction of deuterium. No effects of deuteration on the conformation of the molecule could be detected.
Synthesis of imidazole‐containing poly(iminomethylenes). Choice of N(Im)‐protecting group
Authors: van der Eijk J. M. , Richters V. E. M. , Nolte R. J. M. , Drenth W.
Published: September 2010

Four imidazole‐containing isocyanides having different N(Im)‐protecting groups at the tele as well as at the pros position have been synthesized. These isocyanides include Nτ(Im)‐tosyl‐Nα‐carbylhistamine (4a), Nτ(Im)‐benzyl‐Nα‐carbylhistamine (4b), Nπ(Im)‐benzyl‐Nα‐carbylhistamine (4c) and Nτ,Nπ(Im)‐dibenzyl‐Nα‐carbylhistamine bromide (4d). Compounds 4a and 4d polymerize in the presence of nickel(Il) ions, whereas compounds 4b and 4c do not. This result is explained by the type of nickel complex that is formed, viz. a tetrahedral or square‐planar complex with general formula Ni(CNR)42+ in the case of 4a and 4d, and an octahedral complex with general formula Ni(CNR)32+ in the case of 4b and 4c. In the latter complexes, not only the isocyano groups but also the imidazole groups coordinate to the nickel. Thus, the imidazole groups block the coordination sites which are required for polymerization of the isocyano functions.
A new enzymatic chlorination of barbituric acid and its 1‐methyl and 1,3‐dimethyl derivatives
Authors: Franssen M. C. R. , van der Plas H. C.
Published: September 2010

A new chlorination procedure, involving as reagent the system chloroperoxidase/hydrogen peroxide/potassium chloride was developed for converting barbituric acid, 1‐methylbarbituric acid and 1,3‐dimethylbarbituric acid into their 5,5‐dichloro derivatives. It could be proved that the corresponding 5‐mono‐chlorobarbituric acids are intermediates in the reaction.
The interaction of bacterioopsin with 11,14‐bridged retinals: The synthesis of 13‐demethyl‐11,14‐imino‐, 13‐demethyl‐N‐methyl‐11,14‐imino, 13‐demethyl‐11,14‐thio‐, 13‐demethyl‐11,14‐etheno‐, 11,14‐imino‐retinal and their binding with bacterioopsin
Authors: Muradin‐Szweykowska M. , Peters A. J. M. , Lugtenburg J.
Published: September 2010

The synthesis of the all‐trans and 9‐cis isomers of 11,14‐imino‐retinal, 13‐demethyl–11,14‐imino‐retinal, 13‐demethyl‐N‐methyl‐11,14‐imino‐retinal, 13‐demethyl‐11,14‐thio‐retinal and 13‐demethyl‐11,14‐etheno‐retinal is described.

The interaction of these retinals with bacterioopsin has been investigated. The all‐trans isomers bind to bacterioopsin to form complexes with λmax values around 430 nm. These complexes are stable and do not convert into bacteriorhodopsin analogues. In these complexes the aldehyde group is still present and can be reduced in situ using NaBH4.

The fact that these bridged retinals do not form bacteriorhodopsin analogues must be due either to the steric hindrance or to the electronic perturbations of the system caused by the bridging group.
Photochemistry of 4,5‐dihydro‐8‐hydroxygermacrene B
Authors: Fransen Harrie R. , Dormans Guido J. M. , Bezemer Gerrit J. , Buck Henk M.
Published: September 2010

Irradiation of two racemates of 4,5‐dihydro‐8‐hydroxygermacrene B (2, 3) results, in addition to E‐Z isomerization, in the occurrence of a [1,3]‐C shift. Conformational differences between the diastereoisomers are reflected in a highly stereospecific photoreaction.
P(V) trigonal bipyramidal phosphoranes as model compounds for the description of cAMP‐catalyzed reactions
Authors: van Ool Peter J. J. M. , Buck Henk M.
Published: September 2010

13C NMR low‐temperature investigations have revealed that the dioxaphosphorinane ring, trans‐annelated with a cyclopentane ring (3), prefers an equatorial‐apical alignment in trigonal bipyramidal phosphoranes. However, the 13C NMR low‐temperature investigations of the model compound, in which the dioxaphosphorinane ring is trans‐annelated with a tetrahydrofuran ring (4), have shown that the ligand exchange (pseudorotation) in this compound is very fast on the NMR time scale, even at low temperatures. These results are in fairly good agreement with quantum‐chemical calculations.
Synthesis of retinals labelled at positions 14 and 15 (with 13C and/or 2H)
Authors: Pardoen J. A. , Winkel C. , Mulder P. P. J. , Lugtenburg J.
Published: September 2010

Eight retinals labelled at positions 14 and 15 with 13C and/or 2H were obtained with >98% chemical purity, 92% 13C incorporation, 95% 2H incorporation at position 14 and 99% 2H incorporation at position 15. (14‐13C)retinal, (15‐13C)retinal and (14,15‐13C2)retinal were synthesized from (2‐13C)‐, (1‐13C)‐ and (1,2‐13C2)acetonitrile, respectively, while for the synthesis of (14‐2H)retinal, C2H3CN was used. Via a three‐step process these retinals were transformed into (14,15‐2H2)retinal, (14‐13C,15‐2H)retinal, (15‐13C,15‐2H)retinal and (14,15‐13C2,15‐2H)‐retinal. Their 13C–13C, 13C‐2H and 13C‐1H NMR coupling constants were determined.
Conformational analysis of 3‐oxo 5(10)‐unsaturated steroids. Single‐crystal X‐ray structure analysis of 17‐hydroxy‐7α‐methyl‐19‐nor‐17α‐pregn‐5(10)‐en‐20‐yn‐3‐one (Org OD 14)
Authors: Declercq J.‐P. , van Meerssche M. , Zeelen F. J.
Published: September 2010

Two crystallographically independent molecules with differing half‐chair conformations of ring A were found in the analysis of Org OD 14. These results are compared with published X‐ray structure analyses and Westheimer‐type calculations of related steroids. It is concluded that the energy differences between the half‐chair and envelope conformations of ring A of 3‐oxo 5(10)‐unsaturated steroids are small.
Biomimetic total synthesis of steroids VIII. Stereospecific synthesis of B‐homo‐19‐norsteroids
Authors: Groen M. B. , Zeelen F. J.
Published: September 2010

Cationic cyclization of 2‐[7‐(3‐methoxyphenyl)‐(E)‐3‐heptenyl]‐3‐methyl‐2‐cyclopentenol (7) gave mainly tetracyclic products via Ar1‐6 and/or Ar2‐7 participation. The major product, 3‐methoxy‐17‐methyl‐B‐homo‐1,3,5(10),13(17)‐gonatetraene (9), was converted in two steps into B‐homoestrone methyl ether 20. High‐resolution 1H NMR spectra indicated that the seven‐membered ring in 9 occurs mainly in a boat‐like conformation whereas in its 1‐methoxy isomer 8 it occurs in an unsymmetrical twist‐boat conformation. In 20, the B‐ring probably occurs both in chair and boat conformations.
Synthesis and photooxidation of furylthymines; chemiexcitation model studies
Authors: Feringa Ben L. , Dannenberg W.
Published: September 2010

A method for the synthesis of 1‐(5‐methyl‐2‐furoyl)thymine (7) and 1‐(5‐methyl‐2‐furyl)thymine (8) is described. Trimethylsilyliodide catalysed addition of 5‐methyl‐2,4‐bis(trimethylsilyloxy)pyrimidine (9) to 2‐methyl‐2,5‐dihydro‐2,5‐dimethoxyfuran yielded the new thymine derivative 13. Photooxidations of 7 and 8 gave not the expected addition products but furan endoperoxides and hydroperoxides and the novel rearrangement product 1‐(3‐keto‐1‐butenyl)thymine.
Coal liquefaction ‐ entrapment of bitetralyls and other products from tetralin
Authors: de Vlieger J. J. , de Leeuw J. W. , Kieboom A. P. G. , van Bekkum H.
Published: September 2010

Small scale coal liquefaction experiments are often carried out with tetralin as a model hydrogen donating solvent1–4. Tetralin was thought for a long time to be selectively converted into naphthalene. Recently, however, we have found substantial cracking and isomerization of tetralin under common coal liquefaction conditions, in particular at prolonged reaction times5. The present paper describes further studies of the behaviour of tetralin during coal liquefaction at 400°C, whereby special attention is given to the formation of bitetralyls. Entrapment of these relatively low‐volatile compounds strongly influences data obtained for the coal derived product. This means that the common procedures used to separate coal product and donating solvent are highly insufficient. The structure of the entrapped dimer tetralin compounds has been determined and the mechanism of dimerization is discussed.
sp3‐Carbon detosylations by Dibal‐H≠: Model studies
Authors: Janssen Cornelus G. M. , Hendriks Adrianus H. M. , Godefroi Erik F.
Published: September 2010

α‐ And β‐tosylated alkenylaromatic systems 5c, d and 9a‐c are cyclized to 6c, d and 10a‐c in FSO3H‐containing SO2 in synthetically useful processes. Dibal‐H treatment of α‐substituted 6c, d brings about rapid, high‐yield detosylation to 7c, d; the β‐tosylated isomers 10a‐c give, with Dibal‐H, after 18 h in refluxing toluene, mainly unreacted sulfones together with minor amounts of sulfides 11a‐c. Ring‐disrupted congeners 15a‐d and 18a‐c behave likewise, with α–tosylated 15a‐d being rapidly detosylated by Dibal‐H to 16a‐d and their β‐substituted isomers undergoing low‐yield reductions to sulfides 19a‐c. Dibal‐H mediated detosylation appears to be limited to benzylic substrates.
The chemistry of small‐ring compounds. Part 47. Small‐ring interference in the ozonolysis of cyclopropylidenecycloalkanes
Authors: van den Heuvel C. J. M. , Holland A. , van Velzen J. C. , Steinberg H. , de Boer Th. J.
Published: September 2010

Ozonolysis of olefins Ia‐c containing a cyclopropylidene group, does not follow the classical Criegee mechanism but gives the anomalous products IIa‐c, IIIa‐c,IVa‐c and Va‐c, as outlined in Scheme 2. None of these oxidation products contains the cyclopropyl ring any more. It is suggested that primary ozonides containing a cyclopropyl moiety, undergo already at low temperature simultaneous 0–0 homolysis and small‐ring fission, thus generating the key intermediate 1, 6‐biradical X (Scheme 4). This is at the same time a peroxy and a carbon radical, which upon combination – in casu cyclisation – gives the six‐membered peroxa‐ketone II. Apart from combination, biradical X can also undergo intramolecular disproportionation to the unsaturated ketone XIX (Scheme 8) containing a terminal hydroperoxy function. This product does not accumulate as such, but is further oxidised to the epoxide Va‐c with simultaneous formation of the five‐membered cyclic 1, 3‐oxa‐ketone IIIa‐c (cf Scheme 8). The least oxygen‐rich reaction product is the cyclobutanone IV, for which zwitter ion XIV or its ring‐expanded isomer XV (Scheme 6) is a likely precursor.

Interception of the first zwitter ion by methanol, followed by loss of oxygen, explains the formation of glycol derivatives VI (Scheme 6). Direct attack of XVIII (Scheme 8) on starting material, provides an other route towards the cyclobutanone IV, which is suppressed in the presence of diphenyl sulfide and cinnamic ester.
Electrical properties of a molecular ion channel
Authors: van der Linden J. H. , Nolte R. J. M. , Drenth W. , Schoonman J.
Published: September 2010

A. c. and d. c. electrical conductivities have been determined for complexes of either KCl or K picrate with a polymer of an isocyanide containing benzo‐18‐crown‐6 rings. In both complexes, mixed ionic conductivity occurs. In the KCl complex, chloride ion conductivity predominates. The K‐picrate complex has a low bulk ionic conductivity, but a substantial contribution of cations. The role played by anion‐size effects is discussed.
Behaviour of poly(pyrrole) and poly(N‐methylpyrrole) electrodes in acetonitrile
Authors: Jakobs R. C. M. , Janssen L. J. J. , Barendrecht E.
Published: September 2010

The impedance of poly(pyrrole) (PP) and poly(N‐methylpyrrole) (PMP) films on platinum in an acetonitrile, LiClO4 solution has been measured. At potentials more positive than a characteristic value, the electrodes exhibit porous behaviour and the impedance is determined by the double‐layer capacitance and the solution resistance inside the pores. At more negative potentials, the PP and PMP electrodes behave like flat‐plate electrodes and two impedance contributions can be distinguished, i.e. a material contribution (material resistance and material capacitance) and a contribution from the interphase polymer‐electrolyte (faradaic resistance and double‐layer capacitance).
Enamine synthesis using the Horner‐Wittig reaction. Part 1. (Aminomethyl)diphenylphosphine oxides, new formyl anion equivalents
Authors: Broekhof N. L. J. M. , van der Gen A.
Published: September 2010

Using the Horner‐Wittig reagent (morpholinomethyl)diphenylphosphine oxide (7), aromatic, aliphatic and α, β‐unsaturated aldehydes are converted into morpholino enamines of their homologous aldehydes. With [(N‐methylanilino)methyl]diphenylphosphine oxide (12), the same aldehydes, together with the ketones (cyclic as well as acyclic, both saturated and α, β‐unsaturated), are converted into enamines of their homologous aldehydes. Both types of enamines are converted into the corresponding aldehydes by mild, acid‐catalyzed hydrolysis, showing the utility of 7 and 12, as formyl anion equivalents. Preparation of each geometrical isomer of the N‐methylanilino enamines is possible since the intermediate diastereoisomeric adducts 13 can be separated.
C‐Nitroso compounds. Part XXXVI. Rearrangement of 2‐chloro‐2‐nitrosofenchane and 2‐chloro‐2‐nitrosocamphane
Authors: Lub J. , de Boer Th. J.
Published: September 2010

2‐Chloro‐2‐nitrosofenchane 7 rearranges under the influence of aluminium chloride to the isomeric chloronitrones 9 and 12 (Scheme 3). 2‐Chloro‐2‐nitrosocamphane 18 (Scheme 4) gives, under similar conditions, only one chloronitrone 19, despite the close structural relationship between the starting materials 7 and 18. The chloronitrones react with all common nucleophiles, e.g. with water, to give hydroxamic acids, which can easily be reduced to the amides 4, 5 and 6. The first and last of these amides are not accessible by Beckmann rearrangement of the appropriate oximes.
The influence of substituents on the geometry of the cyclopropane ring. I. The crystal and molecular structure of cyanocyclopropane at −85°C. Film and diffractometer measurements
Authors: Kiers C. TH. , de Boer J. S. A. M. , Heijdenrijk D. , Stam C. H. , Schenk H.
Published: September 2010

Crystals of cyanocyclopropane have been grown from liquid. At −85°C, cell parameters are a = 7.244(5), b = 7.821(2), c = 6.916(3) Å in the orthorhombic space group Pnma with Z = 4. Intensity data were collected in three different ways, viz. photographically using rotation and Weissenberg techniques and electronically by means of a diffractometer. Within the limits of accuracy, the three data sets result in equal bond lengths and angles. The most important result from the structure determination is the difference of 0.033 Å between the lengths of the distal and vicinal ring bonds, which had not previously been measured directly from X‐ray experiments.
3,4‐Dihydro‐2,2′‐pyrromethen‐5(IH)‐ones ; Synthesis and photochemical reactivity
Authors: Koek J. H. , Lugtenburg J.
Published: September 2010

Four isomeric 3,4‐dihydro‐2,2′‐pyrromethen‐5(1H)‐one E/Z pairs were prepared which show not only a photochemical E/Z isomerization but also a photo‐Fries type rearrangement.
Cycloaddition of substituted cyclopropyl ethers to tetracyanoethene
Authors: Wiering P. G. , Steinberg H.
Published: September 2010

The cyclopropyl methyl ethers 2–4, 14 and 15 and tetracyanoethene (TCNE) give, in a multistep cycloaddition, the 1,1,2,2,‐cyclopentanetetracarbonitriles 5–8, 16 and 17. It has been established that the cycloaddition reactions take place with inversion of configuration of the cyclopropyl C2 (or C3) carbon atom and racemization at the C1 carbon atom. In the presence of methanol, the all‐cis‐2,3‐dimethylcyclopropyl methyl ether 3 and TCNE give, in a slow reaction, a mixture of cycloadducts 7 and 8, together with the ring‐opened tetracyanopentanone acetal 13, whereas the phenyl‐substituted cyclopropyl ethers 14 and 15 yield exclusively, and relatively rapidly, the corresponding acetal 19. These results strongly indicate that the reaction proceeds via zwitter‐ions which are formed by SH2‐type attack of TCNE anion radicals on the cyclopropane ring.
Isomeric C5H9O− ions formed in gas‐phase reactions of anions with 2,2‐dimethylpropanal and 2,2‐dimethylcyclopropanol
Authors: Peerboom Renée , Ingemann Steen , Nibbering Nico M. M.
Published: September 2010

Fourier‐Transform Ion‐Cyclotron‐Resonance (FT‐ICR) mass spectrometry has been used to investigate proton abstraction from 2,2‐dimethylpropanal (1) and 2,2‐dimethylcyclopropanol (2) in the gas‐phase. The structures of the C5H9O− ions formed have been probed by studying their reactions with various molecules. The C5H9O− ions derived from 1 and 2 are observed to undergo hydrogen‐deuterium exchange with D2O and to react with C6F6 in a similar way. The results are discussed in terms of five possible structures for the C5H9O− ions: (CH3)3CC̄O (a) magnified image
Photochemistry of dienones. Part 141. The photochemistry of some 9‐demethylated ionyl and ionylidene compounds; a search for, and an example of, η‐hydrogen abstraction
Authors: Visser Cornelis P. , Cerfontain Hans , Geenevasen Jan A. J. , Jorritsma Ruurd
Published: September 2010

The photochemical reactions of some (9‐demethylionyl)‐ and (9‐demethylionylidene)acetones and the corresponding acetophenones have been studied. The β‐isomers 1a and 1b, both under direct and triplet‐sensitized irradiation, undergo (E) ‐ (Z) isomerization of the 7,8‐double bond as the only observed reaction; with 1a, the (E) ‐ (Z) isomerization is followed by a thermal 6e‐electrocyclization with formation of 6. The α‐isomer 2 undergoes (E) ‐ (Z) isomerization both around the 7,8‐ and the 9,10‐double bond.

The aliphatic β‐ionyl ketone 3a, upon irradiation with λ 254 nm, undergoes a sigmatropic [1,5]‐hydrogen shift with formation of the retro‐isomer 9, which, upon electronic excitation, undergoes a Norrish‐type‐II γ‐hydrogen abstraction with formation of the triene 12. The related benzoyl ester 4, upon λ 254 nm excitation, also exhibits the [1,5]‐hydrogen shift with formation of the photostable retro‐isomer 17. Upon (n‐π*) excitation of the aromatic β‐ionyl ketone 3b with λ 350 nm, the triene 12 and acetophenone are formed as primary photoproducts. This photoconversion constitutes the first example of η‐hydrogen abstraction by a benzoyl chromophore directly leading to products by β‐scission of the resulting 1,8‐biradical.
Photochemical conversion of norbornadiene into quadricyclane in the presence of acridinone‐type sensitizers
Authors: Tinnemans A. H. A. , den Ouden B. , Mackor A. , Bos H. J. T.
Published: September 2010

In this study, a series of acridinones and benzo‐fused acridinones have been used for the first time as efficient photosensitizers for the norbornadiene‐quadricyclane isomerization by near UV and visible iradiation. Their triplet energies (240‐280 kJ · Mol−1) are well below the value of 290 kJ · Mol−1 which is generally assumed for norbornadiene. A mechanism is postulated involving an exciplex between sensitizer and norbornadiene.

Limiting quantum yields of 0.5 and higher have been determined for this valence isomerization extrapolated to infinite norbornadiene concentration.

Exciplex formation is supported by measurements of the rate of constant k2 for quenching of excited sensitizer by norbornadiene, yielding values which are much smaller than the diffusion‐controlled quenching constant.
Ar(alk)ylsulfonyl ethyl groups as phosphorus‐protecting functions
Authors: Claesen C. A. A. , Segers R. P. A. M. , Tesser G. I.
Published: September 2010

Various 2‐[Ar(alk)ylsulfonyl]ethanols were prepared and subsequently converted into the corresponding phosphorodichloridites in almost quantitative yield via a convenient synthetic route. The versatility of the method, which obviates the necessity of a distillation step, is demonstrated by the preparation of other Ar(alk)yl phosphorodichloridites, including the unstable benzyl phosphorodichloridite.
A comparison of β‐functionalized ethyl groups for the protection of the phospho function in decathymidylate synthesis using a phosphite triester approach
Authors: Claesen C. A. A. , Segers R. P. A. M. , Tesser G. I.
Published: September 2010

A number of phosphorodichloridites (1) carrying various β‐functionalized ethyl protective groups were converted into their corresponding phosphoromorpholido chloridites (2). These were then reacted with 5′‐O‐(dimethoxytrityl)thymidine to give the pertinent phosphoromorpholidites (3). The applicability of these compounds in the synthesis of oligodeoxynucleotides on a solid support has been evaluated using the synthesis of the thymidine decamer.
Réactions d'addition nucléophile sur les cétones dépendence conformationnelle de l'effet isotopique
Authors: Boyer B. , Lamaty G.
Published: September 2010

In the present investigation, we have measured the secondary deuterium isotope effects in borohydride addition reaction for a serie of cyclohexanones, both hindered and unhindered. We observed an inverse isotope effect, kH/kD < 1.00 for those ketones; these inversions of the isotope effects are discussed in terms of torsional effects and hyperconjugative factor.
Dimetallation of phenylacetylene. Synthesis of ortho‐substituted derivatives of phenylacetylene, benzo[b]selenophene and benzo[b]tellurophene
Authors: Brandsma L. , Hommes H. , Verkruijsse H. D. , de Jong R. L. P.
Published: September 2010

Phenylacetylene can be dimetallated in two ways. o‐K‐C6H4‐C  C ‐ Li is formed by treating phenylacetylene at −70°C with two equivalents of butyllithium and one equivalent of potassium tert‐butoxide in a mixture of tetrahydrofuran and hexane. The dimetallation with BuLi‐N,N,N′, N′‐tetramethylethanediamine (TMEDA) affords a mixture of about 15% (m + p)‐Li‐C6H4‐C  C
Li and 85% o‐Li‐C6H4‐C  C‐Li. Ortho‐K‐C6H4‐C  C‐Li can be transformed into the dilithio or di‐Grignard derivatives by addition of anhydrous lithium bromide or magnesium bromide etherate. Reaction of the dilithio derivative with elemental selenium and tellurium, followed by successive addition of tert‐butyl alcohol and hexamethylphosphoric triamde (HMPT), gives benzo[b]selenophene and benzo[b]tellurophene in good yields.

Regiospecific functionalization of the nucleus via dimetal derivatives succeeds in the case of alkylation, halogenation, sulfenylation and acylation (with dimethylformamide and dimethylacetamide). Trimethylchlorosilane, chloromethyl methyl ether, aldehydes and ketones do not however react regiospecifically.
Synthesis of 16α‐ethyl‐21‐hydroxy‐19‐norpregn‐4‐ene‐3,20‐dione (Org 2058)
Authors: Zeelen F. J. , van den Broek A. J.
Published: September 2010

The syntheses of the title compound and of some ester derivatives are described. These norprogesterone derivatives show interesting progestational activities.