bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomimetic total synthesis of steroids VI. Stereospecific synthesis of 19‐nor‐8α‐steroids and 11α‐alkyl derivatives
Authors: Groen M. B. , Hindriksen B. , Zeelen F. J. 
Published: September 2010

AbstractCationic cyclization of 2‐[6‐(3‐methoxyphenyl)‐(Z)‐3‐hexenyl]‐3‐methyl‐2‐cyclopentenol (7a) produced 1‐ and 3‐methoxy‐17‐methyl‐8α‐gona‐1,3,5(10),13(17)‐tetraene (8a and 9a) with complete stereospecificity. Cyclization of similar substrates with an alkyl substituent in the appropriate position gave exclusively 11α‐alkyl derivatives of 8a and 9a. The products were converted into the corresponding 13α,17α‐epoxides by peracid oxidation and hence into derivatives of 8α‐estrone and 8α‐estradiol. 11α‐Methyl‐8α‐estra‐1,3,5(10)‐triene‐3,17(3‐diol (16b) was obtained in its two enantiomeric forms via resolution of its 3‐methyl ether.
Short‐range structure determination by EXAFS spectroscopy: Theory, experimental technique and spectral analysis
Authors: Vlaic G. , Bart J. C. J. 
Published: September 2010

AbstractA physico‐chemical description of the extended X‐ray absorption fine structure (EXAFS) phenomenon is given and experimental methods for its measurement in transmission mode are indicated. Pros and cons of various procedures for careful evaluation of the experimental absorption data are described, which comprise background removal according to Victoreen's relation or by polynomial fitting and criteria for Fourier filtering methods are given. Three different approaches for EXAFS signal analysis are discussed namely fitting with parametrized amplitude and phase functions, comparison of experimental data with theoretical EXAFS spectra and Fourier transform techniques; the limits of applicability of these procedures are indicated. A critical evaluation is given for the various methods for correction of the resulting radial distribution function in order to comply with crystallographic distances. The determination of coordination numbers is discussed and the procedures are illustrated with results for metallic titanium, rutile and anatase.
Synthesis, spectroscopy and polymerization of methyl α‐([13C,15N]isocyano)propionate; acetic formic anhydride as N‐formylating reagent
Authors: Vlietstra Edward J. , Nolte Roeland J. M. , Zwikker Jan W. , Drenth Wiendelt , Jansen Richard H. A. M. 
Published: September 2010

AbstractMethyl α‐([13C,15N]isocyano)propionate was prepared starting from (±)‐[15N]alanine. The amino acid was converted into the methyl ester, which was formylated with acetic [13C]‐formic anhydride, to afford the methyl ester of N‐[13C]formyl[15N]alanine. Dehydration of the latter compound gave the isocyanide, which was polymerized with nickel chloride. 1H, 13C, 15N NMR and IR data of the labelled compounds are presented.
Coalescence phenomena in the NMR spectra of some cycloheptatrienes
Authors: Zwaard A. W. , Smits H. J. E. , Kloosterziel H. 
Published: September 2010

AbstractCoalescence phenomena have been observed in the NMR spectra of a variety of 7‐substituted 1,3,5‐cycloheptatrienes upon varying temperature and/or solvent. Using two different methods, the energy of activation of the process responsible for coalescence has been determined. Within a group of structurally similar para‐substituted phenyl sulphides a linear relation has been found between the energy of activation and the acidity constant of the corresponding benzenethiol, suggesting the occurrence of ion pairs. The relatively low energy of activation for the phenyl sulphides, when compared with the values of the phenyl sulphones, may result from the structure of the intermediate ion pairs.In addition to the above, a different exchange process between cycloheptatrienyl sulphides and tropylium salt via sulphonium ions has been observed.
A simple synthesis of glycino ethyl ester derivatives of hexachlorocyclotriphosphazene
Authors: Smaardijk A. A. , de Ruiter B. , van der Huizen A. A. , van de Grampel J. C. 
Published: September 2010

AbstractA general method of preparation is described for glycino ethyl ester derivatives of phosphazene‐like ring systems, which may serve as precursors for anti‐cancer drugs.
Intramolecular competition between the di‐π‐methane and the oxa‐di‐π‐methane rearrangements in a triplet‐excited β, γ, β1, γ1‐dienone.
Authors: van der Veen Reinout , Kruk Cornelis , Cerfontain Hans 
Published: September 2010

AbstractThe triplet photosensitization of the β, γ, β1, γ1‐dienone 2 leads to the formation of the DPM isomer 6 and the two ODPM isomers 7 and 8 in a ratio of 35:17:10. This is the first reported example of a substrate which exhibits intramolecular competition as demonstrated by the occurrence of both the DPM and ODPM rearrangement.
The meta‐photocyloaddition of cyclopentene to anisole
Authors: Jans A. W. H. , van Dijk‐Knepper J. J. , Cornelisse J. 
Published: September 2010

AbstractThe meta‐photocycloaddition of cyclopentene to anisole yields the hitherto unknown 1‐methoxy‐exo‐tetracyclo[6.3.0.02,11.03,7 ]undec‐9‐ene together with the endo‐isomer in the ratio 1: 9.3.
The chemistry of small ring compounds. Part 46. Reduction of 1‐halocyclopropyl sulfides by thiolates
Authors: Jorritsma R. , Steinberg H. , de Boer Th. J. 
Published: September 2010

AbstractThe reaction of 1‐halocyclopropyl sulfides with sodium alkanethiolates in protic or aprotic solvents leads to high yields of cyclopropyl sulfides, in which halogen has been replaced by hydrogen. The complementary oxidized product is, in most cases, the thioketone or thioaldehyde derived from the alkanethiolate. The reduction is unaffected by radical scavengers or by oneelectron donors.Reaction kinetics indicate that the reduction proceeds via the 1‐(alkylthio)cyclopropyl cation. A mechanism is discussed (Scheme 9) in which this ambident cation is attacked by thiolate on sulfur. In the intermediary sulfonium ylid an intramolecular hydrogen shift leads to the observed products.
Protonation, and reductive cleavage by lithium of the CS bond, in (methylthio)pentadienylic anions generated from various cis,trans‐isomers of 1‐(methylthio)‐1,3‐pentadiene and 1‐(methylthio)‐1,4‐pentadiene
Authors: Gräfing R. , George A. V. E. , Brandsma L. 
Published: September 2010

AbstractTreatment of the various cis,trans‐isomers of CH3SCHCHCHCHCH3 and CH3SCHCHCH2CHCH2 with a slight excess of potassium amide in liquid ammonia, followed by quenching of the solutions thus obtained with ammonium chloride, gives, in all cases, the is isomer CH3SCH2CHCHCHCH2(> 90% trans) From the anionic solutions 1H NMR spectra have been recorded.Reductive cleavage of the CS bond of the anions CH3SCHCHCHCHCH2⊖ with lithium in liquid ammonia, followed by methylation, leads to almost complete recovery of CH3SCHCHCHCHCH3. During this cleavage, the double bond next to sulfur retains its configuration, while the configuration of the other double bond changes from trans to cis. It remains the same, however, on starting from a (methylthio)pentadiene with a cisC3C4 double bond. The ultimate result of the cleavage procedure with CH3SCHCHCH2CHCH2 is CH3SCHCHCHCHCH3: the configuration of the C1C2 double bond remains the same and the C3C4 double bond is always cis.
Synthesis, characterization and reactivity of boron‐bridged iron(II) dioxime coordination compounds
Authors: Verhage M. , Hoogwater D. A. , van Bekkum H. , Reedijk J. 
Published: September 2010

AbstractReaction of iron(II) dioxime compounds with boron trifluoride diethyl etherate gives clathro compounds. When diphenylboron bromide is used as a reagent, boron‐bridged tetragonal dioxime systems can be prepared via a so‐called pre‐clathro intermediate. This intermediate also shows a tendency to rearrange into a clathro compound. The tetragonal boron‐bridged dioxime compounds Fe(DPGBPh2)2(MeIz)2, Fe(DAGBPh2)2(MeIz)2 and Fe(DMGBPh2)2(MeIz)2 have a structure similar to that of the corresponding hydrogen‐bridged compounds, as deduced from their optical spectra — and for the latter compound, as shown by single crystal X‐ray analysis. They are, however, much more stable towards oxidation. The compounds react with both carbon monoxide and benzyl isocyanide. Coordinated carbon monoxide can be removed by irradiation with light.
Ternary complexes of Zn(II), Cd(II), Co(II) and Ni(II) with 2,2′‐bipyridine or 1,10‐phenanthroline and N‐(thiobenzoyyl)‐N‐phenylhydroxylamine
Authors: Thakur R. S. , Mathur S. P. , Sharma B. K. 
Published: September 2010

AbstractThe stability constants of ternary Zn(II), Cd(II), Co(II) or Ni(II) complexes containing 2,2′‐bipyridinyl (Bipy) or 1,10‐phenanthroline (Phen) and N‐(thiobenzoyl)‐N‐phenylhydroxylamine (TBPH) have been determined in 70% (v/v) dioxane/water medium at 30 ± 1°C and at constant ionic strength (0.1 M NaClO4) in a nitrogen atmosphere. A study of the title metal ions in the presence of an equimolar concentration of the two ligands revealed the formation of mixed‐ligand complexes containing a 1:1:1 molar ratio of metal and the two ligands. These ternary complexes are more stable than would be expected on a statistical basis, i.e. the difference, Δlog KM = log Kmamab ‐ log Kmmb, is positive. This is discussed on the basis of π‐acceptor qualities of the heteroaromatic N‐base and the occurrence of a co‐operative effect due to the π systems of two ligands bound to the same metal ion. The trend in stability constants of the mixed‐ligand complexes of the title metal ions is found to be Ni > Co > Cd > Zn. Mixed‐ligand complexes formed with 1,10–phenanthroline are found to be less stable than those formed with 2,2′‐bipyridine and this is discussed on the basis of steric factors.
The role of histidine in the gastrointestinal hormone secretin
Authors: Voskamp D. , Kranenburg P. , Beyerman H. C. 
Published: September 2010

AbstractEleven analogues of porcine gut secretin, in which the N‐terminal histidine has been modified or deleted, were prepared and assayed for their potency in stimulating the exocrine pancreatic flow in various animal species. Deletion of the α‐amino group, or replacement of the imidazole by the pyrazole ring, resulted in highly potent analogues. Other alterations destroyed most of the potency. All analogues had immunochemical properties similar to those of porcine gut secretin.
Organometal‐mediated synthesis of conjugated allenynes, allenediynes, vinylallenes and diallenes
Authors: Ruitenberg K. , Kleijn H. , Westmijze H. , Meijer J. , Vermeer P. 
Published: September 2010

AbstractAn extensive study of the reactivity of organometallic reagents R3M (R3 = 1‐alkenyl, 1‐alkynyl, 3‐alken‐1‐ynyl, 1,3‐alkadiynyl or 1,2‐alkadienyl; M = Li, MgCl, ZnCl, Cu, Ag) towards R1R2CCCH‐X (1) and R1R2C(X)‐CCH (4) is described. High yields of R1R2CCCHR3 (2) have been obtained by reaction of 1 (X  Br) with R3‐M (M = MgCl, ZnCl or Cu1/2Li1/2) using Pd[PPh3]4 as catalyst. Similarly, pure 2 have been obtained by the Pd[PPh3]4‐catalyzed reaction of 4 (X = Br, OAc, OS(O)Me, OSO2Me, OP(O)(OEt)2) with R3‐M (M = MgCl, ZnCl, Zn1/2, Cu, Cu1/2Li1/2, Ag, or Ag1/2Li1/2). In some reactions with R3‐Cu, compounds 4 were converted into 2 in the absence of the palladium catalyst.
A molecular cation channel
Authors: van Beijnen A. J. M. , Nolte R. J. M. , Zwikker J. W. , Drenth W. 
Published: September 2010

AbstractA polymer of an isocyanide, [RNC<]n has been synthesized in which R contains a benzo‐18‐crown‐6 group. The crown ether rings are situated on top of each other and form channels which bind metal ions.
Convenient synthesis of cyclopenta[c,d]pyrene and 3,4‐dihydrocyclopenta[c,d]pyrene. The reactivity of the pyrene dianion
Authors: Tintel C. , Cornelisse J. , Lugtenburg J. 
Published: September 2010

AbstractThe reactivity of the pyrene dianion has been investigated. Initial attack by electrophiles on the pyrene dianion has been shown to take place exclusively at the 4(9)‐position, leading to mono‐anions (11, 15) which can be converted into 9‐substituted 1,9‐dihydropyrene derivatives (12, 16). The latter can be rearranged to give the novel 4‐substituted 4,5‐dihydropyrene derivatives (13, 17), which provide access to 4‐substituted pyrene derivatives (14, 5). Cyclopenta[c,d]pyrene (1) and 3,4‐dihydrocyclopenta[c,d]pyrene (2), two widespread environmental contaminants, have been synthesized from pyrene in four (64%) and in five steps (62%), respectively, utilizing the chemical properties of the pyrene dianion. In these easy and straightforward syntheses the thus far unknown 4,5‐dihydro‐4‐pyreneacetic acid (17) plays a major role.
Preparation of 11,14‐epoxy‐bridged and isomeric chain‐demethylated retinals. 13‐Demethyl‐11,14‐epoxy‐, 9‐demethyl‐, 13‐demethyl‐ and 9,13‐bisdemethyl‐retinals
Authors: Broek A. D. , Muradin‐Szweykowska M. , Courtin J. M. L. , Lugtenburg J. 
Published: September 2010

Abstract9‐Cis‐ and all‐trans‐13‐demethyl‐11,14‐epoxyretinyl acetate were prepared via a Wittig coupling between β‐ionylidenetriphenylphosphonium bromide (1) and 5‐(acetoxymethyl)furfural. Saponification of these acetates, subsequent oxidation and HPLC separation afforded pure 9‐cis‐and all‐trans‐13‐demethyl‐11,14‐epoxyretinal. 11‐Cis‐ and all‐trans‐9‐demethyl‐, 13‐demethyl‐ and 9,13‐bisdemethyl‐retinal were prepared via the same scheme, based on the Pommer vitamin A acetate synthesis. Their photochemistry shows the same type of solvent dependence as retinal. HPLC separation of the photostationary mixtures of these retinals yielded the all‐trans, 13‐, 11‐, 9‐ and 7‐cis isomers in 98% purity.
Carbonyl and thiocarbonyl compounds XX. Reaction of hydroxybenzaldehydes with o‐phenylenediamine; newer aspects in benzimidazole synthesis
Authors: Latif N. , Mishriky N. , Assad F. M. 
Published: September 2010

AbstractThe nature of the products of the uncatalysed reaction of the o‐hydroxybenzaldehydes 1a‐d with o‐phenylenediamine in boiling ethanol is mainly dependent on the molar ratio of the reactants and the nature of the substituents at the phenyl ring of the aldehyde. In contrast, the m‐ and p‐hydroxy analogues 1e‐g afford exclusively the corresponding 1‐aralkyl‐2‐arylbenzimidazoles 6, regardless of these factors. However, at low temperature, the hydroxybenzaldehydes 1a‐g react with the diamine always giving monoanils (2) regardless of the hydroxy position. The monoanils of the o‐hydroxy aldehydes afford predominantly 2‐arylbenzimidazoles (4) when boiled in n‐butanol. In contrast, those of the m‐ and p‐hydroxy analogues give exclusively 1‐aralkyl‐2‐arylbenzimidazoles (6), whereas, when heated in nitrobenzene, 2‐arylbenzimidazoles (4) are readily obtained. The dianils 5a‐d, upon boiling in butanol, give a mixture of 2‐arylbenzimidazoles (4) and 1‐aralkyl‐2‐arylbenzimidazoles (6), the ratio of which is dependent on the nature of the substituents at the aldehyde. Reaction mechanisms and spectral features of the products are discussed.
Photochemical reactions of 2‐bornanethione (thiocamphor) with bis(methylthio)ethyne. Addition and intramolecular hydrogen abstraction
Authors: Brouwer A. C. , Bos H. J. T. 
Published: September 2010

AbstractIrradiation of a mixture of bornanethione 7 and bis(methylthio)ethyne 2a afforded a mixture of methyl E‐ and Z‐2‐(2‐bornylidene)‐2‐(methylthio)ethanedithioate 8 and E‐1,2‐bis‐(methylthio)vinyl 2‐bornen‐2‐yl sulfide 10E. The first compounds are the products of the (2 + 2)‐photocycloaddition reaction between bornanethione 7 and acetylene 2a. The sulfide 10E is rationalised as being the product of an intramolecular H abstraction reaction of the 1,4‐biradical 12 which is also believed to be the intermediate in the (2 + 2)‐cycloaddition reaction.
Structure and reactivity of the pyrene dianion; a 13C NMR study
Authors: Tintel C. , Cornelisse J. , Lugtenburg J. 
Published: September 2010

AbstractUsing 13C NMR spectroscopy, the pyrene dianion has been shown to be a completely asymmetric system having the highest charge density on the carbon atom at the 4‐position. This result, which is in contrast to that obtained previously on the basis of theoretical calculations, confirms our earlier observations that the pyrene dianion reactivity towards electrophiles is highest at the 4‐position.
Chemistry of crown ethers. Part XXI. Association constants of the complexes of 18‐crown‐6 with dimethyl sulfate, dimethyl carbonate and dimethyl oxalate
Authors: van Zon A. , Onwezen Y. , Tomassen H. P. M. 
Published: September 2010

AbstractThe association constants (K) of the complexes of 18‐crown‐6 with dimethyl sulfate, dimethyl carbonate and dimethyl oxalate have been determined by a 1H NMR method. The K values of these complexes were found to be 0.6, 0.8 and 0.6 l/mol, respectively, which values are several orders of magnitude lower than those reported for crown ether/ammonium salt complexes.
Solutes in sulfuric acid. Part IX. Effect of para‐substitution on the ionization of the oxonium ions of phenol and anisole
Authors: Lambrechts Hans J. A. , Cerfontain Hans 
Published: September 2010

AbstractThe ionization of the oxonium ions of phenol, anisole, 4‐chloro‐ and 4‐methyl‐phenol and 4‐bromo‐, 4‐fluoro‐ and 4‐methyl‐anisole in concentrated aqueous sulfuric acid has been investigated using UV spectroscopy at 25°C. The sulfuric acid concentrations at half‐ionization are within the range 75.2 to 81.8% H2SO4, corresponding with pKa's between ‐5.87 and ‐6.52 based on the H0a acidity function. The substituent effects on the ionization of PhO+ H2 and PhO+ HMe are small, the Hammet ρ values being 0.5 ± 0.1 and 0.9 ± 0.1, respectively.
Empirical force field calculations XXI. The ring inversion of cis‐transoid‐cis‐1,4,4a,5,8,8a,9,9a,10,10a‐decahydroanthracene
Authors: Tavernier D. , Baas J. M. A. , van de Graa B. , Vanhee P. 
Published: September 2010

AbstractThe barrier to the ring inversion of the title compound has been determined using dynamic 13C NMR: ΔG≠253 = 47.9 kJ·mol−1. Empirical force field calculations show that the (half‐chair)chair(half‐chair) ground state inverts in two equi‐energetic steps via the (half‐chair)‐twist(inverted half‐chair) conformer. The calculated ΔH≠ is 46.2 kJ·mol−1 using Allinger's MM2 and 41.7 kJ·mol−1 using White and Bovill's force field.
Preparation of sulfines by alkylidenation of sulfur dioxide using α‐silyl carbanions
Authors: Porskamp P. A. T. W. , van der Leij M. , Lammerink B. H. M. , Zwanenburg B. 
Published: September 2010

AbstractThe synthesis of sulfines 4 from a series of active methylene compounds is described. Deprotonation, followed by silylation, gives the trimethylsilyl compounds 2. Subsequent deprotonation to α‐silyl carbanions and treatment with an excess of sulfur dioxide leads to the formation of sulfines 4, usually in good yields. The experimental conditions of this alkylidenation of sulfur dioxide, using the modified Peterson olefination, are discussed in detail. Hydrolytically sensitive sulfines can be prepared by using a dry work‐up procedure. These sulfines can also be trapped with 2,3‐dimethyl‐1,3‐butadiene to give dihydropyran S‐oxides 5. Reaction of the α‐silyl carbanions with some sulfines leads to alkenes 9, probably through the intermediacy of thiocarbonyl S‐ylides.
Synthesis of two diphosphorylated lipid a derivatives containing α‐ or β‐anomeric phosphates
Authors: van Boeckel C. A. A. , Hermans J. P. G. , Westerduin P. , Oltvoort J. J. , van der Marel G. A. , van Boom J. H. 
Published: September 2010

AbstractThe preparation of two diphosphorylated Lipid A analogues, which contain α‐ or β‐phosphates at the reducing end, is described (i.e. compounds 14d and 15d, respectively). The synthesis of these compounds was accomplished using: (i) two suitably protected glucosamine derivatives, i.e. the non‐reducing part 6 and the reducing part 3; (ii) an iridium catalyst to isomerize the anomeric allyl ethers quantitatively into 1‐propenyl ethers, which can then be removed to give simultaneously oxazoline functions (i.e. isomerization of 4b into 5 and of 7a into 7b); (iii) the levulinoyl* group for temporary protection of the 4‐hydroxyl group; (iv) 1‐hydroxybenzotriazole‐activated phosphorylating agents for the phosphorylation of the 4′‐hydroxyl group (i.e. phosphorylation of compound 8 to give 10a,b); (v) 2,2,2‐tribromoethyl phosphate for the phosphorylation of the reducing anomeric centre of Lipid A analogues (i.e. phosphorylation of 11a,b to afford 13a,b).Non‐reducing part 6 and reducing part 3 were reacted together to give the disaccharide 7a, which was converted into non‐phosphorylated Lipid A precursor 8. Phosphorylation of compound 8 at its 4′‐hydroxyl function and at its reducing anomeric centre resulted in the formation of fully protected α‐phosphorylated Lipid A analogues 14a and 14b together with the fully protected β‐phosphorylated analogues 15a and 15b. Final removal of all the protecting groups from 14a,b and 15a,b gave the α‐phosphorylated Lipid A analogue 14d and the β‐phosphorylated Lipid A analogue 15d, respectively.
Synthesis of 3‐ (1 ‐alkenyloxy) ‐1,2‐propanediols, enol ethers of glycerol, by the horner‐wittig reaction
Authors: van Schaik T. A. M. , van der Gen A. 
Published: September 2010

AbstractReaction of the anion derived from phosphine oxide 4 with saturated and unsaturated aldehydes provides diastereomeric mixtures of the adducts 5. After removal of the protecting group these can be separated and, upon reaction with base, afford the pure E‐and Z‐isomers of glyceryl enol ethers 7 in good yields.
Electrical and catalytic properties of some mixed conductors with the fluorite or pyrochlore structure
Authors: van Dijk M. P. , ter Maat J. H. H. , Roelofs G. , Bosch H. , van de Velde G. M. H. , Gellings P. J. , Burggraaf A. J. 
Published: September 2010

AbstractIn view of their possible use as electrocatalysts the conduction properties and the catalytic activity for CO oxidation of some lanthanide titanates partly substituted with Bi, and some Nd zirconates, partly substituted with Ce, have been determined. The lanthanide ion, the substitution and the ordering in the zirconates all influence the conduction properties and the catalytic activity.
Synthesis and complex formation of a novel, flexible, biomimetic, benzimidazole‐containing, dinucleating ligand
Authors: van Rijn J. , Reedijk J. 
Published: September 2010

AbstractThe synthesis and complex formation with copper(II) of a new symmetric octadentate N6O2 ligand is described. The ligand 1,1,10,10‐tetrakis(1‐methylbenzimidazol‐2‐ylmethyl)‐1,10‐diaza‐4,7‐dioxadecane (megtb) is prepared by condensation of o‐phenylenediamine and [ethylene‐bis(oxyethylenenitrilo)]tetraacetic acid, followed by methylation. This ligand appears to yield dinuclear compounds with copper(II) salts with different kinds of bridging anions. Some spectroscopic and magnetic properties of these compounds, as well as the structure of a representative compound Cu2(megtb)F2(BF4)2(H2O) 2, are reported as examples
Synthesis of α‐substituted γ,δ‐unsaturated β‐oxo esters
Authors: van den Goorbergh J. A. M. , van der Gen A. 
Published: September 2010

AbstractTwo approaches to the synthesis of the title compounds 3 are described. The first consists of direct alkylation of the unsaturated β‐oxo esters 1 via their monoanions. The best results were obtained using the heterogeneous sodium methoxide/alumina system. Isolation of pure, mono‐α‐alkylated compounds requires chromatographic separation of the reaction products. The second approach makes use of the Horner‐ Wittig reaction. α‐Substituted phosphine oxides 4 were converted into their dianions and reacted with aldehydes and ketones to afford the mono‐α‐alkylated β‐oxo esters 3 in good yields. The requisite phosphine oxides were obtained from the corresponding γ‐bromo β‐oxo esters 10 via an Arbusov reaction with ethyl diphenylphosphinite. Finally, it was found that α,α‐dialkylated and α,αγ‐trialkylated β‐oxo esters 8 and 15 can be obtained by reaction of 1 with an excess of alkyl halide in the presence of two or four equivalents of sodium hydride, respectively.