bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of bicyclic boroxazolidones from aziridine‐2‐carboxylic esters
Authors: Legters Johan , Thijs Lambertus , Zwanenburg Binne
Published: September 2010

Aziridine‐2‐carboxylic esters 1 were converted into bicyclic boroxazolidones 3 in a three‐step sequence. First, the ester groups were hydrolyzed either by sodium hydroxide or with lithium hydroxide in methanol. The salts thus obtained were acidified with acetic acid or through a weakly acidic ion‐exchange resin. Treatment of the zwitterionic aziridine‐2‐carboxylic acids 2 with triethyl‐borane in hexane gave boroxazolidones 3 in high yields. Boroxazolidone 3g, obtained from optically active 1g was reconverted to the starting material by 8‐hydroxyquinoline without any loss of optical activity.
SYNthesis LIBrary, an expert system for chemical‐reaction knowledge‐base management
Authors: Chodosh Daniel F. , Hill John , Shpilsky Lev , Mendelson Wilford L.
Published: September 2010

SYNLIB (SYNthesis LIBrary) is an expert system which allows laboratory scientists to rapidly and interactively search databases of chemical reaction information. SYNLIB is fully supported on personal computer and RISC workstation platforms and requires minimal computer expertise on the part of the chemist. By encouraging hands‐on access to information, SYNLIB allows complex chemical synthesis concepts to be presented directly to the practicing laboratory scientist. SYNLIB searching enables the user to query chemical reaction knowledge bases for matches to combinations of structural and non‐structural chemical questions. We discuss the design considerations for expert systems specifically for chemists and present an analysis of the chemical‐reaction information available from the published literature. A search for the formation chemistry of functionalized α,β‐unsaturated ketones is used to illustrate the search strategies available.
Generalization and representation of synthesis pathways in the COSYMA system
Authors: Hamm P. , Jauffret P. , Kaufmann G.
Published: September 2010

A new approach of computer‐assisted design of organic synthesis is proposed with the COSYMA system. It is based on the similarity between the target molecule and an intermediate or the final product of a well‐known synthesis pathway. Similarity between two molecules is defined as equality of the structures obtained by applying generalization rules to these two molecules. Similarity criteria are described, and associated generalization rules expressed. A new internal representation of synthesis pathways is also described, which fits COSYMA requirements, and consists of time‐independent structural and temporal parts. The temporal part describes variations of atom connectivity in the different synthesis steps.
Acetalation studies. Part IXΦ. Reaction of sucrose and some related sugars with acetone in the presence of iodine; a novel cleavage‐isopropylidenation methodψ
Authors: Verhart Cor G. J. , Caris Brigitte M. G. , Zwanenburg Binne , Chittenden Gordon J. F.
Published: September 2010

An efficient cleavage‐isopropylidenation reaction of sucrose, catalyzed by iodine, is described. Related D‐fructofuranosyl‐containing oligosaccharides, some common disaccharides and their individual monosaccharide units were treated in a similar manner to yield isopropylidenated monosaccharide derivatives. The reaction conditions are particularly mild and selective. Some mechanistic aspects of the procedure are also discussed.
Iodonium ion‐mediated glycosidations of phenyl selenoglycosides
Authors: Zuurmond H. M. , van der Klein P. A. M. , van der Meer P. H. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Fully benzylated or benzoylated phenyl selenoglycosides can be activated by the promoters iodonium di‐sym‐collidine perchlorate (IDCP) or N‐iodosuccinimide and catalytic triflic acid (NIS/TfOH cat.). The potential of the iodonium ion‐mediated glycosidations of phenyl selenoglycosides is illustrated in the chemoselective synthesis of 1,2‐cis‐or 1,2‐trans‐linked disaccharides.
Sulfonation of [2.2]paracyclophane; structures and modes of formation of the products
Authors: van Lindert Helen C. A. , Koeberg‐Telder Ankie , Cerfontain Hans
Published: September 2010

The sulfonation of [2.2]paracyclophane (1) with (i) sulfur trioxide in the presence of various amounts of dioxane as moderator in dichloromethane as solvent, and (ii) in sulfuric acid containing 98.5 wt‐% H2SO4 acting both as reagent and solvent was studied. The introduction of the first sulfo group is rapid relative to the second one, which always enters only the non‐sulfo‐containing phenylene ring. The rate of sulfonation of 1 with SO3 greatly exceeds that of the acyclic analogue 1,2‐di(p‐tolyl)ethane (2). With 98.5 wt‐% H2SO4, the main product is the ps‐gem isomer, i.e., the 4,15‐disulfonic acid (83%) in addition to the ps‐ortho isomer, and smaller amounts of the ps‐meta and ps‐para isomers. With SO3 as reagent, the sulfo products are 1–4,15‐disulfonic anhydride, and the ps‐ortho, ps‐meta and ps‐para disulfonic acids. On using 4.0 equiv. of SO3, the main product is the 4,15‐disulfonic anhydride (87%). However, with increasing amounts of added dioxane, the yields of the three disulfonic acids increase at the expense of the 4,15‐disulfonic anhydride. Mechanisms for the formation of the sulfo products under the different reaction conditions are suggested and discussed. The relatively high degree of 4,15‐disulfonic anhydride formed in the sulfonation of 1–4‐sulfonic acid with SO3 in the absence of dioxane is explained in terms of intramolecular sulfonation.

X‐ray crystal structures for potassium 1–4‐sulfonate and 1–4,15‐disulfonic anhydride were obtained. The former compound suffers from steric strain due to the forced close proximity of the sulfonate group and the C(2)H(2,1), whereas the additional 4,15‐SO2‐O‐SO2‐ bridge of the latter one leads (i) to a very significant strain with the nearest, i.e., the C(3)C(14) ethylene bridge, and (ii) induces some rotation of the two p‐phenylene moieties around the C(3)C(6) and C(11)C(14) axes in opposite directions, the C(4)C(15) interatomic distance being larger than that of the C(8)C(13).
Reactions of ω‐phenylalkenes with sulfur trioxide; sulfonation and Friedel‐Crafts type of cyclization
Authors: Schonk Ruud M. , Bakker Bert H. , Cerfontain Hans
Published: September 2010

Reactions of ω‐phenylalkenes1a‐31awith sulfur trioxide were studied in the temperature range −60 to 25°C using dichloromethane as solvent and 1.5 mol equiv. of dioxane as reactivity moderator. ω‐Phenylalkenes1a‐7areact just like simple alkenes: at low temperature, they yield the (thermally unstable) β‐sultones1b‐7band4c‐7c, which at 25°C are converted into the corresponding carbyl sulfates. Reactions of ω‐phenylalkenes8a‐10a, which have a ‐(CH2)3‐ linkage between the Ph and the C = C moieties, with 1.1 equiv. of SO3at −60°C yield very rapidly and quantitatively the 1‐(1‐sulfoalkyl)‐1,2,3,4‐tetrahydronaphthalenes8fand9f (= 10f). Reaction of ω‐phenylalkenes11aand12a, having a ‐(CH2)2‐ linkage between Ph and C = C, with 1.1 mol equiv. of SO3at − 60°C leads to quantitative and stereospecific formation of 1‐methyl‐1,2,3,4‐tetrahydronaphthalene ‐2‐sulfonic acids11hand12h, respectively. The 5‐(chlorophenyl)‐2‐pentenes13a‐16aclearly demonstrate the presence of β‐sultones13b‐16band13c‐16cas the sole initial products leading to the Friedel‐Crafts cyclization products13h‐16h. Reaction of 1,3‐diphenyl‐1‐propenes26aand27awith 1.5 equiv. of SO3at − 60°C quantitatively yields β‐sultones26cand27c, which upon raising the temperature to − 20°C, are slowly converted intotrans‐1‐phenylindane‐2‐sulfonic acid (34).

Attempted intermolecular Friedel‐Crafts type of sulfoalkylation of arenes using β‐sultones as reagent failed. Reaction of, for example,trans‐4,5‐octanesultone with anisole instead led only to transfer sulfodeprotonation, to yield(E)‐4‐octene and 4‐methoxybenzenesulfonic acid. Mechanisms for the formation of the various products are suggested.
The influence of substituents on the geometry of the cyclopropane ring. VI The molecular and crystal structures of cyclopropanecarboxylic acid and cyclopropanecarbonyl chloride
Authors: de Boer J. S. A. M. , Stam C. H.
Published: September 2010

Crystals of cyclopropanecarboxylic acid, C4H6O2, grown from the liquid are triclinic, space groupP1, a =8.6992(6),b= 8.8017(4),c= 6.6930(3) Å, α = 103.71(1), β = 103.93(1), γ = 66.49(1)° (171 K); Z = 4. The finalRfor 1649 independent observed reflexions [I > 3σ(I)] is 0.037. Crystals of cyclopropanecarbonyl chloride, C4H5OCl, grown from the liquid are monoclinic, space groupP21/m. a= 6.287(2),b= 7.092(2),c= 5.647(3) Å, β = 101.84(3)° (151 K); Z = 2. The finalRfor 446 independent observed reflexions is 0.042.

The C=O groups in the molecules of both compounds are in the bisectings‐cisconformation. The distal bonds in the cyclopropyl rings have (average) lengths of 1.463(2) and 1.467(2) Å, the average vicinal bond lengths are 1.514(2) and 1.516(2) Å for the acid and the carbonyl chloride respectively (corrected for libration).
The isomerization of α‐pinene oxide with Brønsted and Lewis acids
Authors: Kaminska J. , Schwegler M. A. , Hoefnagel A. J. , van Bekkum H.
Published: September 2010

α‐Pinene oxide (2) is a very reactive substrate which isomerizes rapidly under the influence of acid catalysts. A large number of products can be formed from a single intermediate. Selectivity to the industrially important campholenic aldehyde can be achieved with metal‐halogen compounds, especially zinc chloride and zinc bromide. A possible explanation for this behaviour is offered, stipulating a stabilized carbenium‐ion intermediate. Protonic catalysts are typically highly active but unselective. No evidence was found for the earlier reported selectivity to campholenic aldehyde with zeolite catalysts.
Enzymatic enantioselective ester hydrolysis by carboxylesterase NP
Authors: Smeets J. W. H. , Kieboom A. P. G.
Published: September 2010

The enzymatic hydrolysis of a series of carboxylic esters by carboxylesterase NP has been investigated in order to determine the scope and limitations of this enzyme. 2‐Substituted propionates were hydrolyzed with high enantioselectivity when an aromatic moiety was part of the 2‐substituent. Enantioselective hydrolysis could be accomplished with several 2‐arylpropionates, 2‐(aryloxy)propionates and N‐arylalanine esters. The propionate esters yielded propionic acids as (S) enantiomers, whereas the alanine esters yielded the (R) enantiomers. Without a 2‐aryl substituent, the enzymatic hydrolysis of the propionates occurred at a lower rate without acceptable enantioselectivity. In addition to 2‐substituted propionates, only a few other esters were hydrolyzed with high enantioselectivity by carboxylesterase NP, such as some prochiral disubstituted malonates. 1‐Phenylethyl acetate was the only substrate with chirality in the alcohol part of the ester that was found to be hydrolyzed enantioselectively.

Carboxylesterase NP proved to be a powerful enzyme for kinetic resolution of propionate esters with an aromatic ring containing a 2‐substituent.
Intramolecular charge‐transfer fluorescence of 1‐phenyl‐4‐[(4‐cyano‐1‐naphthyl)methylene]piperidine (fluoroprobe) as a sensor for phase transitions in the solid state
Authors: Jenneskens Leonardus W. , Verhey Herman J. , van Ramesdonk Hendrik J. , Verhoeven Jan W. , van Malssen Kees F. , Schenk Henk
Published: September 2010

As evidenced by temperature‐dependent wide‐angle X‐ray diffraction (WAXD), the thermochromism of the continuous and time‐resolved (nanosecond time scale) fluorescence behaviour of 1‐phenyl‐4‐[(4‐cyano‐1‐naphthyl)methylene]piperidine (fluoroprobe) dissolved in octadecyl octadecanoate is shown to be a highly sensitive probe for a phase transition in the solid state occurring in the latter.
Synthesis of specifically stable‐isotope‐labeled l‐proline via L‐glutamic acid
Authors: Cappon J. J. , van der Walle G. A. M. , Verdegem P. J. E. , Raap J. , Lugtenburg J.
Published: September 2010

(3,4‐13C2)‐L‐proline and (15N)‐L‐proline were prepared from the correspondingly labeled L‐glumatic acids via a single scheme in high yield and on a gram scale. The synthetic route is based on the ring closure of L‐glutamic acid to L‐5‐oxoproline and the selective reduction of the 5‐amide function, without interference with the 2‐carboxylate function and the asymmetric center. The selective reduction is effected by first converting the amide into the corresponding thioamide and subsequently reducing the thioamide to the amine using tributyltin hydride, in combination with protection and deprotection steps. In earlier work we described the preparation of L‐glutamic acid isotopically labeled at any position or combination of positions starting from simple highly enriched synthons. The synthetic scheme in this publication makes L‐proline, 13C‐ or 15N‐labeled at any position or combination of positions, easily available. The labeled L‐prolines are characterized by 1H‐, 13C‐ and 15N‐NMR and mass spectrometry.
Synthesis and physicochemical properties of decanucleotides containing (3′→ 5′)‐O‐CH2‐O‐linkages at predetermined positions
Authors: Quaedflieg P. J. L. M. , Pikkemaat J. A. , van der Marel G. A. , Kuyl‐Yeheskiely E. , Altona C. , van Boom J. H.
Published: September 2010

Synthesis of the modified decadeoxynucleotides 16–20 having the sequence d(G1pC2pG)3pT4x1T5x2T6x3T7pG8pC9pG10) and containing one (x2 = CH2, x1 = x3 = p, i.e., 16), two (x1 = x3 = CH2, x2 = p, i.e., 17, x2 = x3 = CH2, x1 = p, i.e., 18 and x1 = x2 = CH2, x3 = p. i.e., 19) or three (x1 = x2 = x3 = CH2, i.e., 20) ‐O‐CH2‐O‐ linkages could be accomplished using the respective mono‐, di‐ or tri(‐O‐CH2‐O) 3′‐O‐phosphoramidites 6, 10 and 14 as the incoming synthons. Hybridization of 16–20 with their native complementary strand afforded stable duplexes, which were studied by 1D‐ and 2D‐1H‐NMR and UV‐hyperchromicity techniques.
Medicinal chemistry: Past, present and future
Authors: So W.
Published: September 2010

Drug discovery in the past and, to a lesser extent, at present has been (is) based on molecular manipulation of natural products. In this way, selective local anesthetics have been developed from cocaine

From atropine via pethidine, potent morphinomimetics, anti‐tussives, anti‐diarrhea agents and neuroleptics of the butyrophenone type have been developed.

New lead compounds can also be discovered by general pharmacological screening of new chemical entities, synthesised with a certain pharmacological property in view, but lacking the expected potency. The discovery of the anti‐ulcer agent omeprazole is an example of this approach. Chemical manipulation of known bioactive compounds may also lead to new drugs. The possibility of rational design of new, highly sophisticated and specific drugs depends largely on progress made in the exact understanding, at the molecular level, of agonist/antagonist‐receptor and protein‐protein interactions.
Synthesis and biological properties of selected nucleoside analogues
Authors: Koomen G. J.
Published: September 2010

This paper reviews the research carried out in our laboratory in the field of nucleoside analogues, divided into two main parts: (1) Analogues with modified sugars, describing synthesis of monomers for polynucleotides, in which the ribose moiety has been replaced by amino acids, N‐vinyl‐2‐pyrolidinone, dihydroxy acyclic systems, tetrahydrofuran and tetrahydropyran rings, butyrolactone, pyrrolidine and cyclopentane/cyclopentane systems. (2) Analogues with modified bases, consisting of carbene adducts of pyrimidine nucleosides, benzodiazepine nucleosides, 5‐fluoro‐6‐vinyluracil, glutarimide nucleosides, transition state and suicide inhibitors of adenylosuccinate lyase and fluorescent pyrido[2,1‐i] purine nucleosides. Cytostatic and antiviral activities of a variety of the compounds obtained are discussed.
Industrial transformations of penicillins and cephalosporins
Authors: Verweij Jan , de Vroom Erik
Published: September 2010

A survey is presented of transformations of penicillin G into penicillin and cephalosporin derivatives. Amongst other things the issues discussed are the conversion of penicillin G into 6‐aminopenicillanic acid (6‐APA) and some semi‐synthetic penicillins, ring expansion of the penicillin nucleus giving the cephalosporin nucleus and subsequently 7‐aminodeacetoxycephalosporanic acid (7‐ADCA), and the synthesis of various 3′‐substituted cephalosporin derivatives, including the tert‐butyl ester of 3‐(bromomethyl)‐7‐(phenylacetamido)‐3‐cephem 1‐oxide (3‐BMC®).
Synthesis of 6β‐methyl analogues of mifepristone, new selective antiprogestagens
Authors: van den Heuvel M. J. , Groen M. B.
Published: September 2010

A new strategy is described to synthesize 19‐norsteroids with substituents at C‐6, C‐11 and C‐17. The strategy is applied to the synthesis of 11β‐[4‐(dimethylamino)phenyl]‐6β‐methyl‐4′, 5′– ‐dihydrospiro[estra‐4,9‐diene‐17,2′‐(3′H)‐furan]‐3‐one (15, Org 31710) and some related compounds. These compounds have been shown to have potent antiprogestational activity and, compared to previously described 11‐aryl‐19‐norsteroids, much reduced affinity for the glucocorticoid receptor.
Reactions of cumulated and conjugated dienes with sulfur trioxide
Authors: Schonk Ruud M. , Bakker Bert H. , Cerfontain Hans
Published: September 2010

The reactions of a series of cumulated (1a‐5a) and conjugated alkadienes (8a‐13a) with sulfur trioxide have been studied in the temperature range of −60 to 25°C using dichloromethane as solvent and 1.5 equiv of dioxane as reactivity moderator. Reaction of tetramethylallene (1a) at low temperature yielded the β‐sultone 1b, which at 0°C was slowly converted into 2,4‐dimethyl‐1,3‐pentadiene‐3‐sulfonic acid (1f). This conjugated dienesulfonic acid, in the presence of additional SO3, at 0°C, was rapidly converted into the unsaturated δ‐sultone 1g. Reaction of 1,2‐ cyclononadiene (5a) with SO3, formed an exception to the generally observed formation of the unsaturated δ‐sultones g, as at low temperatures a 1:1 mixture of 2‐cyclononene‐2,1‐sultone (5b) and the corresponding carbyl sulfate (5d) was formed. These products at 0°C were both converted into the same alkadienesulfonic acid, viz. 6. Upon using an excess of SO3, 6 was rapidly converted into 3‐cyclononene‐1,2‐sultone‐3‐sulfonic acid (7).

Reaction of the conjugated alkadienes 8a‐13a with sulfur trioxide led to the formation of the similar unsaturated δ‐sultones 8g‐13g, as observed upon starting with the cumulated dienes 1a‐5a. The reactions of SO3 with the conjugated alkadienes 9a‐12a clearly demonstrate that the formation of the δ‐sultones proceeds non‐stereospecifically. The formation of the unsaturated δ‐sultones from the alkadienes 1a‐5a and 8a‐13a is, therefore, suggested to proceed via a two‐step reaction, viz. An initial [2s + 2s] cycloaddition, followed by very fast conversion of the resulting β‐sultone into the unsaturated δ‐sultone g.
Sulfonation of 1‐ and 2‐naphthol and their methanesulfonate esters with sulfur trioxide. The influence of initial sulfation on the sulfo‐product composition
Authors: Ansink Harold R. W. , Zelvelder Erwin , Cerfontain Hans
Published: September 2010

The sulfonation of 1‐ and 2‐naphthol with sulfur trioxide in C2H3NO2 has been studied by using 1H NMR. 1‐Naphthol (1) yields, upon reaction with 1.0 mol‐equiv of SO3, a mixture of 2‐ and 4‐sulfonic acids (2‐ and 4‐S); upon increasing the reaction temperature, the relative amount of 2‐S increases. Upon reaction with 4.0 mol‐equiv of SO3, the initially observed products are the hydrogen sulfate 1‐O,2,4‐S3, and some corresponding sulfonic anhydrides. After prolonged reaction times, some 1‐O‐4,7‐S3, is formed.

2‐Naphthol (3), upon reaction with 1.0 mol‐equiv of SO3, yields a 85: 15 mixture of 1‐S and 8‐S, whereas upon reaction with 2.0 mol‐equiv of SO3, a 8: 14: 78 mixture of the 5‐S, 6‐S and 8‐S are formed. Sulfonation of 3, either by (i) reaction with 1.2 and, subsequently, an additional 2.0 mol‐equiv of SO3, or (ii) by direct addition of 4.0 mol‐equiv of SO3, yields a mixture of the carbyl sulfates 5‐5‐S and 5‐6‐S and the hydrogen sulfate 3‐O,6,8‐S3, the relative yield depending on the method used.

The results are discussed in terms of initial formation of the corresponding naphthyl hydrogen sulfates and on the basis of a comparison with the reactions of 1‐ and 2‐naphthyl methanesulfonates, the chosen model compounds for the hydrogen sulfates, with SO3.
Conformational analysis of cis‐fused eudesm‐11‐en‐4‐ols
Authors: Kesselmans R. P. W. , Wijnberg J. B. P. A. , Schrijvers R. , Sudhölter E. J. R. , de Groot Ae.
Published: September 2010

The conformational behaviour of the four cis‐fused stereoisomers 1–4 of eudesm‐11‐en‐4‐ol has been investigated using NMR spectroscopy. In addition, the conformational behaviour of these compounds has been simulated with molecular‐mechanics calculations using the MM2(87) force‐field program. Comparison of the results obtained from NMR analysis and MM2 calculations shows that the outcome of both methods agree very well.
Coordination compounds of tripeptides and pentapeptides containing L‐histidyl residues. Studies towards structural models for the active site of copper proteins
Authors: Hulsbergen F. B. , Reedijk J.
Published: September 2010

Five small, completely protected, L‐histidyl(NτBzl)‐containing peptides, were synthesized and characterized by NMR spectroscopy, i.e., R‐Ala‐His(Nτ‐Bzl)‐Ala‐R′ (1), R‐His(Nτ‐Bzl)‐Ala‐Ala‐Ala‐Met‐R′ (2), R‐His(Nτ‐Bzl)‐Ala‐Ala‐Ala‐His(Nτ‐Bzl)‐R′ (3), R‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐R′ (4), R‐His(Nτ‐Bzl)‐Ala‐His(Nτ‐Bzl)‐R′ (5), in which: R is phenylacetyl (PhCH2CO‐), R′ is phenylamino (‐NHPh); Bzl is benzyl (PhCH2‐).

It has been shown that benzylation of histidine residues takes place at the Nτ atom of the imidazole. The resulting peptide derivatives appear to be good ligands for CoII, ZnII and CuI. Titrations of zinc chloride solutions towards peptide solutions (in dmso‐d6, dimethyl sulfoxide followed by NMR spectroscopy show the formation of the two species [Zn(NπHis)2Cl2] and [Zn(NπHis)(dmso)Cl2]. Copper(I)‐chloride titrations result in formation of trigonal planar and tetrahedral complexes (in dmso‐d6). Zinc, copper and cobalt trifluoromethanesulfonates were also investigated, and corresponding tetrahedral species with additional dmso ligands replacing chloride were obtained. In addition, octahedral complexes have been found, as shown for cobalt(II) using ligand‐field spectroscopy.

Conductivity experiments of zinc chloride complexes in dmso and chloroform indicate non‐electrolytes. Their very low conductivity in methanol indicates only slight dissociation of chloride, in agreement with a tetrahedral geometry for zinc(II). For [Co(NπHis)2Cl2], the UV‐VIS adsorption spectra in dmso and in the solid state (diffuse reflection) are comparable, indicating tetrahedral geometry, with a CoN2Cl2 chromophore.
Self‐assembling chiral metallo‐clefts; synthesis and molecular structure of N,N′‐bis(12H‐benzo[α]xanthen‐12‐ylidene)‐1,2‐ethanediamine zinc(II)‐dichloride complex
Authors: Barf Tjeerd , Jansen Johan F. G. A. , van Bolhuis Fré , Feringa Ben L. , Spek Anthony L.
Published: September 2010

Bulky ligands for cleft‐type metal complexes were synthesized from thio ketones and diamines in yields varying from 20–80%. A molecular structure determination of one ligand N,N′‐bis(12H‐benzo[a]‐xanthen‐12‐ylidene)‐1,2‐propanediamine (19) was performed. A metallocleft was constructed by a self‐assembling process with zinc(II) chloride. A crystallographic study of this zinc complex (24) revealed surprisingly that an anti‐syn inversion of the imine moieties of the ligand had taken place during complexation.
Rapid charge migration within 1,4‐benzoquinone stacks in the solid phases of 2,5‐Di‐n‐decoxy‐1,4‐benzoquinone
Authors: Keegstra E. M. D. , Zwikker J. W. , Jenneskens L. W. , Schouten P. G. , de Haas M. P. , Warman J. M. , Schouten A. , Kooijman H. , Spek A. L.
Published: September 2010

Temperature dependent, radiation‐induced conductivity measurements of 2,5‐di‐n‐decoxy‐1,4‐benzoquinone (1) unambiguously show that self‐assembly of the 1,4‐benzoquinone moieties into stacks is a prerequisite for rapid electron and/or hole migration.
A remarkable halogen‐zinc exchange reaction; X‐ray crystal structure of (2‐iodozincio‐1,3‐xylylene)‐15‐crown‐4
Authors: Gruter Gert‐Jan M. , Akkerman Otto S. , Bickelhaupt Friedrich , Smeets Wilbert J. J. , Spek Anthony L.
Published: September 2010

An unprecedented halogen‐metal exchange was observed in the reaction between (2‐iodo‐1,3‐xylylene)‐15‐crown‐4 and diethylzinc, which resulted in the formation of (2‐iodozincio‐1,3‐xylylene)‐15‐crown‐4. An X‐ray crystal structure of this product is presented.
Polymer‐supported solution synthesis of a heptaglucoside having phytoalexin elicitor activity
Authors: Verduyn R. , van der Klein P. A. M. , Douwes M. , van der Marel G. A. , van Boom J. H.
Published: September 2010

An efficient synthesis of methyl heptaglucoside 2 using poly(ethyleneglycol)monomethyl ether as a polymer support is described. Elongation of the acceptor 11, anchored via a succinoyl linkage to PEG, with the appropriate glycosyl donors 4–6 and intermittent protective group manipulations gave fully protected heptamer 18. Deprotection of 18 furnished, after purification as its peracetate, title compound 2 in a good overall yield.
Potential usefulness of sugar 1,2 thio ortho esters in iodonium‐promoted glycosidation
Authors: Zuurmond H. M. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Sugar 1,2 thio ortho esters can be condensed with terminal glycosyl acceptors using iodonium‐ion sources (IDCP and NIS/TfOH) as activators. IDCP‐ or NIS/TfOH‐assisted glycosidation of sugar 1,2 thio ortho esters with primary hydroxyl groups of “armed” or “disarmed” ethyl (phenyl) 1‐thioglycosides gave the respective disaccharides having 1,2 ortho ester or 1,2 trans interglycosidic linkages.
Synthesis of 2,3‐dihydro‐I H,4 H, 6 H‐furo[3,4‐b]pyrrolo[1,2‐a]quinoline‐6a(7H)‐carbonitrile; a novel type of intramolecular tetrahydrofuran formation
Authors: Verboom Willem , Morzherin Yury , Kelderman Erik , Engbersen Johan F. J. , Reinhoudt David N. , van Hummel Gerrit J. , Harkema Sybolt
Published: September 2010

Appropriately 4‐substituted 1,2,3,3a,4,5‐hexahydro‐3a‐(methoxymethyl)pyrrolo[1,2‐a]quinolines 3 cyclize to 2,3‐dihydro‐1 H,4H,6H‐furo[3,4‐b]pyrrolo[1,2‐a]quinoline‐6a(7H)‐carbonitrile (5) upon heating in polar solvents, the reaction being accelerated by lithium bromide. The formation of the annulated tetrahydrofuran ring of 5 takes place via intramolecular attack of the oxygen atom of the methoxymethyl substituent at C‐3a on the electrophilic carbon atom at C‐4. The structure of 5 was confirmed by single‐crystal X‐ray structure determination.
Synthesis of 7‐substituted 6‐demethoxythebaines and Diels‐Alder reaction of 7‐methoxy‐5β‐methyl‐6‐demethoxythebaine (chemistry of opium alkaloids, part XLI)
Authors: Woudenberg R. H. , Meuzelaar G. J. , Maat L.
Published: September 2010

Mesylation of 7‐acetoxyneopine(4), followed by reductive cleavage of the acetyl group gave 6α‐O‐mesyl‐7α‐hydroxyneopine(6), in which the hydroxyl group was protected as a methoxymethoxy group. Elimination of the mesyl ester yielded 7‐(methoxymethoxy)‐6‐demethoxythebaine(7). For the 5β‐methyl analogue, we started from 6‐O‐acetyl‐7α‐hydroxy‐5β‐methyl‐neopine(5), which was converted into9via hydroxyl protection as a methoxymethoxy group and removal of the acetyl group. Mesylation and elimination gave 7‐(methoxymethoxy)‐5β‐methyl‐6‐demethoxythebaine(10). Hydrolysis of7and10afforded the salutaridine analogue11and 5β‐methyl‐6‐deoxyneopin‐7‐one(12), which were easily converted into the 7,7‐dimethoxy‐6‐deoxyneopine analogues13and14. Elimination of methanol from14yielded the desired diene15. Diels‐Alder reaction of15with ethyl acrylate yielded exclusively the 8β‐substituted 6β,14β‐ethenomorphinan16, due to α‐face approach. Cycloaddition of diene15with maleic anhydride gave the 6α, 14α‐ethenoisomorphinan17and the 6β,14β‐ethenomorphinan18in a ratio of 5: 4. The outcome of the Diels‐Alder reactions is discussed in relation to the substituents at the 5β‐ and 7‐positions combined with an asynchronous cycloaddition mechanism.
Unexpected phenomena in glycosylations of acceptors with L‐idose configuration
Authors: Spijker Nynke M. , Basten Jan E. M. , van Boeckel Constant A. A.
Published: September 2010

For the synthesis of Galß(1 → 4)IdoA disaccharides 1, several glycosylations of L‐iduronic acid derivatives 5 and 13 and of L‐idopyranose derivative 21 were performed with differently protected D‐galactopyranosyl donors under various conditions. It was found that these coupling reactions mainly led to the formation of the undesired α‐interglycosidic linkage, even when the donor contained a participating group at C‐2. On the other hand, coupling of the corresponding D‐glucopyranosyl donor 19 with 13 led to a much higher β/α ratio (2/1). By changing the conformation of the acceptor into the 1,6‐anhydro‐L‐idopyranose acceptor 23, 90% of the desired β‐coupled disaccharide was obtained in the glycosylation with galactopyranosyl donor 12. Finally it was found that the α/β ratio of the condensation with 25, promoted by an insoluble silver salt, was influenced in an unusual way by the substituents at the galactosyl bromide.
The influence of substituents on the geometry of the cyclopropane ring. VII The molecular and crystal structures of bicyclopropylidene (C3H4C3H4) and (dicyclopropylmethylene)cyclopropane [(C3H5)2CC3H4]
Authors: de Boer J. S. A. M. , Stam C. H.
Published: September 2010

Crystals of bicyclopropylidene grown from the liquid are monoclinic, space group P21/n, a = 4.9744(3), b = 12.4870(8); c = 4.0366(3) Å, β = 95.077(7)° (173 K), Z = 2. The final R for 450 independent observed reflections is 0.036.

Crystals of (dicyclopropylmethylene)cyclopropane grown from the liquid are monoclinic, space group P21/a. a = 16.781(2), b = 7.260(1), c = 13.665(1) Å, β = 99.28(1)° (123 K), Z = 8. The final R for 2592 independent observed reflections is 0.046.

The dimensions of the cyclopropylidene moiety in the molecules of both compounds are very similar. The (average) lengths of the distal bonds are 1.549 and 1.547 Å, respectively, and the (average) length of the vicinal bonds is 1.472 Å in both molecules. The average dimensions of the cyclopropane rings in the molecules of the second compound are 1.505 Å for the distal and 1.513 Å for the vicinal bonds. There is a significant difference between the lengths of the double bonds in the two compounds [1.307(2) and 1.327(2) Å, respectively; all distances corrected for librational motion of the molecules].
Reaction of C60, C70, C76, C78, and C84 with ozone at 23.5°C
Authors: Heymann Dieter , Chibante L. P. Felipe
Published: September 2010

C60, C70, C76, C78, and C84 dissolved in toluene, were treated at 23.5°C with ozone. The concentrations of all five fullerenes decreased with increasing dose of ozone, but C60, C76, C78, and C84 transformed significantly faster than C70. Oxides of C60 and C70, but not of the other fullerenes, were observed in the ozonated solutions. We assume that all five fullerenes form molozonides, which swiftly lose molecular oxygen to form oxides. We assume further that the molozonide always forms at an interpentagonal bond. The π‐bond orders calculated by Taylor for such bonds may explain the faster ozonation of C76, C78, and C84, but probably not of C60. We suggest that the “equatorial belt” of 15 hexagons of C70, with its relatively high π density may be the cause for the slower rate of ozonation of C70.
New pyridinecarbonitriles from fluoro arylpropenones
Authors: Mishriky N. , Asaad F. M. , Girgis A. S. , Ibrahim Y. A.
Published: September 2010

The facile synthetic approaches to 3‐pyridinecarbonitriles are described. The first approach involves the base‐catalyzed transformation of 4‐hydroxy‐1,1‐cyclohexanedicarbonitrile 2a into 4a, b. The other route involves the base‐catalyzed multi‐step one‐pot reaction of aryl methyl ketones with the appropriate arylidenemalononitriles 6, 11a, b. Careful study of the synthesis of 2a, b from 1a, b revealed the importance of controlling the reaction conditions. Thus, 1,7‐dioxo‐4,4‐heptanedicarbonitriles 3a, b or 3‐pyridinecarbonitrile 4a were obtained in addition to the desired 2a, b under different basic conditions.
Crystal Structure and Silver Ion Complexation of a Novel Porphyrazine Substituted with four Dithiacrown ether Rings
Authors: van Nostrum Cornelus F. , Benneker Franciscus B. G. , Nolte Roeland J. M. , Veldman Nora , Spek Anthony L. , Schouten Arend‐Jan
Published: September 2010

The synthesis of magnesium porphyrazines substituted with sulfur‐containing 15‐crown‐5 and 18‐crown‐6 macrocycles is reported as well as the single crystal structure of the 18‐crown‐6 substituted porphyrazine; the larger crown ether compound is shown to form dimers with Ag+ ions, unlike the porphyrazine with the smaller crown ether rings.
Synthesis and Physical Properties of Highly Ca2+‐Tolerant Disodium 2‐(Sulfatomethyl)‐1‐Alkylsulfate Surfactants
Authors: Kooreman Peter A. , Engberts Jan B. F. N.
Published: September 2010

The synthesis, critical micelle concentrations (CMC) and Krafft temperatures (TKrafft) of a series of disodium 2‐(sulfatomethyl)‐1‐alkylsulfates (2a‐d) are presented, with alkyl being n‐tetradecyl (C14), n‐hexadecyl (C16), n‐octadecyl (C18) and n‐eicosyl(C20). The surfactants exhibit a large Ca2+‐tolerance in aqueous solutions.
Microemulsions as reaction media. Self‐organizing assemblies in an environmental cleanup problem
Authors: Menger F.M. , Park H.
Published: September 2010

A microemulsion system has been developed that simultaneously destroys three environmental contaminants by combined oxidative/hydrolytic pathways. The method is rapid, cheap, and mild. No special equipment (stirrer, heater, photolyzer, etc.) is required. Self‐organization converts a seemingly intractable 8‐component mixture into a useful system, a tactic discovered by living cells long ago.
Organonickel(II) complexes containing aryl ligands with chiral pyrrolidinyl ring systems; syntheses and use as homogeneous catalysts for the Kharasch addition reaction
Authors: van de Kuil Lucia A. , Veldhuizen Yvonne S. J. , Grove David M. , Zwikker Jan W. , Jenneskens Leonardus W. , Drenth Wiendelt , Smeets Wilberth J. J. , Spek Anthony L. , van Koten Gerard
Published: September 2010

New chiral organonickel(II) complexes 3a‐d have been synthesized containing monoanionic terdentate ligands of the type 2,6‐bis[(1‐pyrrolidinyl)methyl]phenyl. Chirality is introduced

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at the nitrogen donor atoms, which are part of the pyrrolidinyl ring systems, by placing substituents on the 2 or 5 positions of the rings. The complexes have been characterized variously by 1H‐ and 13C‐NMR spectroscopy, UV/Vis spectroscopy and X‐ray crystallography.

Crystals of 3b are monoclinic, space group P21, with a = 11.572(2), b = 11.804(2), c = 13.249(3) Å, β = 107.00(2)°, Z = 4, final R = 0.043 for 3043 observed reflections. Crystals of 3c are tetragonal, space group P412121, with a = b = 12.2957(14) Å, c = 26.418(3) Å, Z = 8, final R = 0.052 for 1479 observed reflections. Crystals of 3d are tetragonal, space group P412121, with a = b = 11.0869(5), c = 21.718(2) Å, Z = 4, final R = 0.046 for 1469 observed reflections.

The catalytic ability of the nickel complexes in the addition reaction of polyhalogenated compounds with alkenes (Kharasch addition) is markedly influenced by the geometry around the nickel atom and only 3a and 3b prove to be effective catalysts. The highest enantiomeric excesses of 16‐17% obtained with 3b and L‐menthyl methacrylate in this catalytic reaction indicate that the C2 chiral fence produced by the Me‐substituted pyrrolidinyl rings is not very effective for the transfer of chiral information.
A LHASA analysis of taxol
Authors: van Rozendaal Erik L. M. , Ott Martin A. , Scheeren Hans W.
Published: September 2010

A retrosynthetic analysis using the computer program LHASA of the promising antitumor agent taxol (1) is described, which resulted in a synthetic route with the following key steps: an intramolecular Diels‐Alder reaction generating the AB rings, and the coupling reactions of the required diene and dienophile with a CD‐ring fragment. The feasibility of the route is studied by comparing the LHASA analysis with related chemistry from the literature. Finally, a critical discussion about the usability of the LHASA program for the planning of complex organic molecules is given.]
Synthesis of 3‐alkenylcephalosporins using an epoxide mediated wittig reaction
Authors: de Vroom Erik , van der Wal Anton , Lugtenburg Johan
Published: September 2010

The synthesis of 3‐alkenyl cephalosporins 5 using an epoxide mediated Wittig reaction is described. Reduction of the 3′‐triphenylphosphonium cephalosporin‐1‐oxide 4 followed by condensation with acetaldehyde in the presence of 1,2‐epoxybutane gave, after purification, the 3‐propylidene derivative 5 (R1=CH3) in 39% yield.
Synthesis of L‐histidine specifically labelled with stable isotopes
Authors: Cappon J. J. , Witters K. D. , Baart J. , Verdegem P. J. E. , Hoek A. C. , Luiten R. J. H. , Raap J. , Lugtenburg J.
Published: September 2010

(2′‐13C)‐, (1′‐15N)‐ and (3′‐15N)‐L‐Histidine were prepared according to a synthetic scheme that allows the 13C or 15N labelling of all carbon and nitrogen positions or any combination of positions. A 1,5‐disubstituted imidazole ring was constructed via condensation of tosylmethyl isocyanide with 3‐phenylpropenal and subsequent cycloaddition of benzylamine. The imidazole intermediate was converted into 1‐benzyl‐5‐(chloromethyl)‐imidazolium chloride which was coupled to a glycine moiety via an enantioselective coupling with the bislactim ether of cyclo‐D‐valylglycine. Deprotection of the coupling product afforded L‐histidine in high optical purity. Syntheses for the isotopically labelled synthons were developed starting from simple, commercially available, highly enriched compounds. The labelled L‐histidines were characterized by mass spectrometry and 1H‐, 13C‐ and 15N‐NMR spectroscopy.
A new model for coenzyme B12 based on a Costa‐type ligand
Authors: Altink R. , van Arkel B. , van der Baan J. L. , Balt S. , De Bolster M. W. G. , van Delft R. J. , Klumpp G. W. , De Koning H. , van den Winkel Y.
Published: September 2010

The synthesis of a new Costa‐type ligand (H2mdo), in which the propylene bridge has been replaced by a methylenedioxy bridge has been accomplished: two molecules of butanedione monoxime are coupled via a CH2 group by reaction with CH2Cl2 and 50% aqueous NaOH in the presence of a phase‐transfer reagent. Dihalidocobalt and alkyl(halido)cobalt complexes of the deprotonated ligand have been prepared and structurally characterized by NMR spectroscopy.
Efficient route to highly functionalized tetrahydrofurans by stereocontrolled silicon‐directed cyclization
Authors: van Delft F. L. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Cyclization of 3,4,6‐tri‐O‐benzyl‐2,5‐di‐O‐trimethylsilyl‐1‐deoxy‐1‐phenyldiisopropylsilyl‐L‐glucitol in the presence of BF3·Et2O or catalytic H2SO4 proceeds stereoselectively to give predominantly the fully benzylated 2,5‐anhydro‐L‐glucitol derivative without occurrence of the Peterson elimination.
Nucleophilic substitutions using O‐alkyl‐N,N′‐dialkylisoureas. Applications to ephedrines
Authors: Poelert Martin A. , Kellogg Richard M. , Hulshof L. A.
Published: September 2010

Dialkylcarbodiimides in the presence of a Cu1 catalyst react cleanly with the hydroxyl group of N‐methylated (1R,2S)‐ephedrine and (1S,2S)‐pseudoephedrine. These adducts react with nucleophiles like alkyl and aryl thiols as well as thioic acids and phthalimide to form the substitution products with overall retention of configuration. It is postulated that intramolecular participation of the amino group via an SN2 reaction leads to aziridium salts, which are subsequently opened by the nucleophiles via a second SN2 reaction. This synthetic approach is also useful for the inversion of simple secondary alcohols; on treatment with dicyclohexylcarbodiimide followed by benzothioic acid and treatment with LiAlH4, menthol was converted in good yield to neomenthane thiol.
Selective hydrogenation of acetic acid towards acetaldehyde
Authors: Pestman R. , Koster R.M. , Ponec V.
Published: September 2010

As a model reaction for the selective hydrogenation of carboxylic acids towards aldehydes, the reaction of acetic acid towards acetaldehyde has been investigated. Various oxides are used as catalysts, including platinum‐enriched oxides. It appeared that oxides with a moderate metal‐oxygen bond strength are good catalysts, provided that a source of activated hydrogen is present. On exposure to molecular hydrogen zero‐valent metals can produce activated hydrogen. Addition of precious metals, such as Pt, or completely reducing part of the oxidic catalyst can provide the zero‐valent metal. The hydrogenation probably occurs on the oxidic surface by a Mars and Van Krevelen type of mechanism.
An infrared spectroscopic study of CO and NO adsorption on bimetallic Pd‐Rh/SiO2 catalysts
Authors: Mergler Y.J. , Ramsaransing D.R.G. , Nieuwenhuys B.E.
Published: September 2010

Pure Pd/SiO2, pure Rh/SiO2, and bimetallic PdRh/SiO2 catalysts, with Pd and Rh in the atomic ratios of 75/25 at% and 50/50 at%, were studied by means of infrared (IR) spectroscopy. Spectra of adsorbed CO and NO were recorded in the temperature range from 298 to 573K. The IR spectra obtained for the bimetallic catalysts exhibit characteristic features of both Pd and Rh. The results point to the presence of alloy crystallites with properties between those of the constituent metals. Most likely the PdRh(1:1)/SiO2 catalyst consists of small Rh clusters or atoms, surrounded by Pd, whereas for the PdRh(3:1)/SiO2 catalyst the surface consists primarily of Pd. However, in the presence of NO, Rh migrates to the surface, due to the dissociation of NO and the concomitant oxidation of the metal particles. No indication of mixed sites, consisting of both Pd and Rh atoms, was found. The results are compared with those previously reported for Pt‐Rh catalysts.
Direct imaging of catalytic surface reactions in the field‐ion microscope: The oxidation of hydrogen on platinum
Authors: Block J.H. , Drachsel W. , Gorodetskii V.V.
Published: September 2010

A field‐ion microscope (FIM) was used in the investigation of hydrogen oxidation at temperatures between 300 K and 430 K and pressures of p(O2) = 5 · 10−4 mbar, p(H2) = 3 · 10−4 to 7 · 10−4 mbar. The H2O molecules produced act as an imaging gas and display the catalytically active surface area. The structure‐sensitive H2O formation was studied under steady‐state conditions or in the oscillatory regime or in form of chemical waves. The displacement of Pt lattice atoms is spectacular in the Pt(100) plane, where the transformation from (1 × 1) Pt(100) to hex Pt(100) can be directly imaged.
Adsorption of biacetyl on Rh/SiO2 catalysts: An FTIR study
Authors: Beutel Tilman , Moroz Boris L. , Knözinger Helmut
Published: September 2010

Biacetyl (butane‐2,3‐dione) adsorbs to silica via H bonding. Splitting of the central C‐C bond occurs on adsorption on Rh particles in Rh/SiO2 catalysts. The resulting surface‐acetyl species seems to undergo rapid decomposition even at temperatures below 300K and leads to the formation of chemisorbed CO and methyl fragments. Based on the principle of microscopic reversibility, it is concluded that acetyl species may be formed under catalytic conditions from chemisorbed CO and methyl species by migratory insertion of CO into the metal‐carbon bond of a chemisorbed methyl fragment.
The effect of propane activation over Ga‐modified H‐ZS M‐5 catalysts
Authors: Ivanova Irina I. , Derouane Eric G. , Blom Niels , Hamid Sharifah B. Abdul
Published: September 2010

In situ 13C MAS NMR was used to investigate the influence of total and partial pressure of propane on the initial stages of its conversion over a Ga/H‐MFI catalyst (2‐13C). Propane was the labelled reactant. Different pressures were achieved by varying the amounts of propane and of nitrogen as diluent in the cell. The nature of primary and secondary labelled reaction products depends on total pressure. High total and partial pressures of propane enhance bimolecular primary formation of n‐butane and isobutane via a BREST (Bifunctional Reaction Step) mechanism1. Low total pressure leads to methane and polymeric fragments as primary products. A reaction pathway including the formation of a polymeric hydrocarbon‐chain intermediate is proposed to account for secondary isobutane formation at low pressure. The influence of pressure on reaction equilibria and kinetics and on adsorption and exchange processes is discussed.
A model for the enantioselective hydrogenation of pyruvate catalysed by alkaloid‐modified platinum
Authors: Simons K.E. , Meheux P.A. , Griffiths S.P. , Sutherland I.M. , Johnston P. , Wells P.B. , Carley A.F. , Rajumon M.K. , Roberts M.W. , Ibbotson A.
Published: September 2010

A LEED and XPS study of the adsorption of naphthalene, quinoline, and 10,11‐dihydrocinchonidine on Pt(111) at 300K has shown that only naphthalene forms an ordered ad‐layer, and that quinoline and the alkaloid adsorb in a disordered state and without decomposition. These experiments do not support the hypothesis of ordered adsorption of alkaloid that forms the basis of the template model for the interpretation of enantioselectivity in Pt‐catalysed pyruvate hydrogenation. The model is accordingly reviewed. Molecular modelling studies show that a highly specific 1:1 interaction between cinchonidine (or cinchonine) and pyruvate interprets the observed sense of the enantioselectivity, provided relative energy relationships derived for purely inter‐molecular interactions are valid for the same molecules in the adsorbed state. Moreover, the ‘product’ of this 1:1 interaction is a satisfactory precursor to the H‐bonded state considered responsible for the greatly enhanced rate that always accompanies enantioselective reaction over cinchona‐modified Pt. The previously published dependencies of optical yield on (a) surface concentration of adsorbed cinchonidine modifier, and (b) modifier composition for mixtures of quinine and quinidine, are shown to be in quantitative agreement with the proposed 1:1 interaction model and at variance with the ordered adsorption model. Catalysts modified and used under strictly anaerobic conditions show negligible activity and enantioselectivity demonstrating that oxygen plays a crucial role in successful catalyst preparation. XPS experiments confirm that adsorption of cinchonidine from air‐saturated ethanolic solution on Pt(111) provides an adlayer containing both alkaloid and adsorbed oxygen. (S)‐(‐)‐1‐benzyl‐pyrrolidine‐2‐methanol, various configurations of ephedrine, D‐and L‐histidine and the methyl esters of D‐ and L‐tryptophan have been examined as modifiers for supported Pt. Although there is evidence that these compounds can provide chiral direction to pyruvate hydrogenation, rate enhancement is slight and enantioselectivity is correspondingly low.
The reaction of α‐amino‐substituted diphenylphosphine oxide anions with elemental sulfur and selenium: A new route to thio‐ and selenoamides
Authors: Otten P.A. , van der Gen A.
Published: September 2010

The lithiated anions of α‐amino‐substituted diphenylphosphine oxides 1, in which R can be hydrogen, aryl, alkyl and alkenyl, react with two equivalents of sulfur or selenium to form thio‐ and selenoamides, which can be isolated in good to excellent yields in most cases. The optimal reaction conditions (temperature and time) were found to depend both on the phosphine oxide used and on the chalcogene. A mechanism is presented which accounts for the stoichiometry of the reaction.