Isomeric Ketones Research Articles

Formation of enol and acyl phosphine ligands via alkylation of a tungsten phosphaallyl complex: crystal structures of [WI{C6H4(PH2)[PMeC(O)CH2(C6H4Me-4)]-1,2}(CO)(η-C5H5)]·0.5C4H8O and [WI{C6H4(PH2)[P{(CH2)4I}C(O)CH2(C6H4Me-4)]-1,2}(CO)(η-C5H5)

The π-phosphaallyl complex [W{σ,η3-C6H4(PH2)[PC(OH)CH(C6H4Me-4)]-1,2}(CO)(η-C5H5)]1 has an unused lone pair of electrons on the central phosphorus atom of the chelate ring and like a conventional PR3 ligand will undergo facile P-alkylation reactions. Methylation (Me3OBF4, CH2Cl2, 20°C) at the allylic phosphorus affords the co-ordinated enol-phosphine salt [W{σ2,η2-C6H4(PH2)[PMeC(OH)CH(C6H4Me-4)]-1,2}(CO)(η-C5H5)][BF4]2. Complex 2 is stable in CH2Cl2 but MeCN displaces the enol group (1 d, 20°C), affording [W{σ2-C6H4(PH2)[PMeC(OH)CH(C6H4Me-4)]-1,2}(MeCN)(CO)(η-C5H5)]+3, which subsequently undergoes very slow (10 d, 20°C) enol–keto tautomerisation to the ketone isomer [W{σ2-C6H4(PH2)[PMeC(O)CH2(C6H4Me-4)]-1,2}(MeCN)(CO)(η-C5H5)]+4. Deprotonation of the hydroxyl group in 2(Et3N, MeCN) affords the neutral metallaphosphacyclobutanone complex [W{σ3-C6H4(PH2)[PMeC(O)CH(C6H4Me-4)]-1,2}(CO)(η-C5H5)]5 which undergoes facile O-methylation (Me3OBF4, CH2Cl2) affording [W{σ2,η2-C6H4(PH2)[PMeC(OMe)CH(C6H4Me-4)]-1,2}(CO)(η-C5H5)][BF4]6, a methoxy derivative of the hydroxy precursor 2. The methoxyvinyl group in 6 is slowly displaced by MeCN (3 d, 20°C), affording the cation [W{σ2-C6H4(PH2)[PMeC(OMe)CH(C6H4 Me-4)]-1,2}(MeCN)(CO)(η-C5H5)]+7. The presence of the methoxy group in 7 prevents enol–keto tautomerisation. The reaction of complex 1 with Mel (CH2Cl2, 20°C) initially affords a yellow precipitate of [W{σ2, η2-C6H4(PH2)[PMeC(OH)CH(C6H4Me-4)]-1,2}(CO)(η-C5H5)]I 8 which then slowly dissolves and simultaneously isomerises to [Wl{σ2-C6H4(PH2)[PMeC(O)CH2(C6H4Me-4)]-1,2}(CO)(η-C5H5)]9. The related reaction of 1 with 1,4-diiodobutane gives [Wl{σ2-C6H4(PH2)[P{(CH2)4I}C(O)CH2(C6H4Me-4)]-1,2}(CO)(η-C5H5)]10, an n-butyl iodide analogue of 9. The molecular structures of 9 and 10 have been established by single-crystal X-ray diffraction studies and are extremely similar. The tungsten atoms carry a cyclopentadienyl ring and are ligated by the o-phenylene bidentate phosphine, iodide, and CO ligands. In both cases the iodide ligand lies trans to the PH2 end of the bidentate phosphine ligand. The alkylated phosphorus atom of the bidentate phosphine ligand carries a methyl (9) or an n-butyl iodide (10) group, and an acyl group C(O)CH2C6H4Me-4 which has arisen from isomerisation of the enol moiety C(OH)C(H)C6H4Me-4 in the precursor 1. The alkyl groups lie syn to the cyclopentadienyl rings which is consistent with stereospecific alkylation of the phosphorus lone pair in complex 1. Spectroscopic data (IR and 1H, 13C-{1H}, and 31P NMR) for the new tungsten complexes are discussed and mechanisms proposed to account for their formation.

ChemInform Abstract: Reactivities of Stable Rotamers. Part 24. Formation of Isomeric Ketones by Cyclization of Rotameric 3‐Methyl‐3‐(1,2,3,4‐tetrahalo‐9‐triptycyl)butanoyl Chloride and Barriers to Isomerization of the Ketones.

AbstractThe rotameric alkenyltriptycenes (III) and (IV) isomerize in boiling 1‐chloronaphthalene and serve to prepare the ketones (VII) and (VIII) via carboxylic acids (V) (and their rotamers, from (III)).

Reactivities of Stable Rotamers. XXIV. Formation of Isomeric Ketones by Cydization of Rotameric 3-Methyl-3-(1,2,3,4-tetrahalo-9-triptycyl)butanoyl Chloride and Barriers to Isomerization of the Ketones

Abstract Rotational isomers of 3-methyl-3-(1,2,3,4-tetrahalo-9-triptycyl)butanoic acid, where the halo is either fluoro or chloro have been prepared. Cyclization of their acid chlorides afforded ap- and sc-ketones from ap- and sc-isomers, respectively. The barriers to isomerization were 29.9 and 26.8 kcal mol−1 at 363 K, for the fluoro and the chloro ketones, respectively, for the ap→±sc process. The equilibrium constants (sc/ap) at 363 K were 2.34 and 18.5 for the fluoro and the chloro compounds respectively. The barriers to isomerization and the relative stabilities of the isomeric ketones were discussed based on the MMP2(NONPLANAR) calculation results and the steric congestion in the ground state.

ChemInform Abstract: Novel Products from Beckmann Fragmentation of Camphor Oxime in Polyphosphoric Acid.

AbstractHeating of camphor oxime (I) with PPA affords the four isomeric ketones (IIa)‐(V) besides the known fragmentation products (VI) and (VII) (yields in g, depending on time and work‐up conditions).

Novel products from Beckmann fragmentation of camphor oxime in polyphosphoric acid

Heating camphor oxime with PPA affords, besides the known fragmentation products isoaminocamphor ( 4) and β-campholenonitrile ( 13), four isomeric ketones C 10H 14O resulting from intramolecular acylatlon of the intermediate α-campholenonitrile ( 3). The ketones have been identified as 5-ketocamphene ( 6), 6-ketocamphene ( 8), tricyclenone ( 9), and endo -2,4-dimethylbicyclo[3.2.1]oct-2-ene-7-one ( 14). The latter results from a novel ring expansion, probably by way of a protonated cyclopropane.

Microbiological reductions of enantiomeric 2-oxo-1,4-cineoles

A selection of bacteria, fungi and yeasts known to achieve ketone reduction reactions were assessed for their abilities to transform enantiomeric 2-oxo-1,4-cineoles to their respective alcohol products. Microbiological reduction of the (−)- ketone isomer led to the formation of a preponderance of the corresponding endo-alcohol isomer with all organisms, indicating that ‘re’-face reductase specificity predominates. The (+)- ketone isomer gave mixed results. Curvularia lunata formed a preponderance of the endo-alcohol isomer, indicating the presence of ‘si’-face specific reductases in this organism, while Penicillium frequentans gave a higher proportion of the exo-alcohol isomer, indicating the presence of ‘re’-face specific reductases. Kinetic studies showed that constant ratios of exo/endo-alcohol products were obtained when (+)- 2-'oxo-1,4-cineole is reduced by C. lunata, but that the ratios of alcohol isomers changed with time when reductions were catalyzed by P. frequentans.

13C magnetic resonance studies. 131. An examination of β-enolization in an unsaturated [3.2.1] system: 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one

Under homoenolization conditions (t-BuO−/t-BuOH/185 °C), 3,3-dimethylbicyclo[3.2.1]oct-6-en-2-one (5) is converted into six products through three reaction pathways. The major product, 3,3-dimethylbicyclo[3.3.0]octan-2-one, arises by unidirectional β-enolate rearrangement of 5 to the isomeric unsaturated [3.3.0] ketones, which (a) undergo efficient reduction to 2, by single electron transfer, and (b) suffer Haller–Bauer cleavage to two isomeric 2,2-dimethyl-3-cyclopentenylpropanoic acids. In competition with these processes is the reversible conjugate addition of t-BuO− to 5 to furnish the 6-tert-butoxy derivative, which undergoes β-enolate rearrangement to two isomeric ketones. The structures of these products were established primarily from their 1H and 13C magnetic resonance spectra.

A study of three reactions leading to isomeric 2-(N,N-disubstituted amino)thiazol-5-yl ketones

N-Imidoyl-N,N-disubstituted thioureas react with α-halogeno ketones in the presence of triethylamine to give the expected 2-(N,N-disubstituted amino) thiazol-5-yl ketones in high yield. The corresponding reactions of N-acyl-N,N-disubstituted thioureas lead to mixtures of these products and isomers which arise from rearrangement between cyclic intermediates. Mixtures of the isomeric thiazolyl ketones are also formed by treating N,N-disubstituted thioureas with 2-bromo 1,3-diketones. The mixtures from the second and third routes contain the same products but in significantly different proportions. A mechanistic scheme which accounts for the main findings was developed.During the work 40 new 2-(N,N-disubstituted amino)thiazol-5-yl ketones were prepared and their structures rigorously established; characteristic mass spectral fragmentation patterns were particularly useful in identifying the substituents at positions 4 and 5 of the thiazole ring.

ChemInform Abstract: Nitrogen Insertion in Isolongifolane/Longibornane Systems via Beckmann/Schmidt Rearrangements: A Comparative Study.

AbstractWhile the ketone (II) can be transformed to the lactone (I) using method A) or B) and oxidized to the lactone (III) (yield given in mg), the isomeric ketone (VIII) remains unchanged under these conditions.

Interaction of fluorine-containing ?-aminovinyl ketones with amines

Isomeric fluorine-containing β-aminovinyl ketones react with ammonia and amines primarily at the enamine electrophilic site, regardless of the positions of the amino group and fluoroalkyl substituent, forming transamination products.

Reactions of electrophilic alkynes with some iron and tungsten sulphur, selenium, and arsenic complexes

Reactions of [Fe(AsMe2)(CO)2(η5-C5H5)], [W(AsMe2)(CO)3(η5-C5H5)], and [W(SR′)(CO)3(η5-C5H5)] with activated alkynes CF3CCCF3 and/or MeO2CCCCO2Me afford metallacyclic complexes [[graphic omitted]sMe2}(CO)(η5-C5H5)], [[graphic omitted]sMe2}(CO)2(η5C5H5)](R = CF3 or CO2Me), and [[graphic omitted]R′}(CO)2(η5-C5H5)](R = CF3, R′= Prn; R = CO2Me, R′= Pri or Prn) or the η2-vinyl complex [W{η2-C(CF3)C(CF3)C(O)SR′}(CO)2(η5-C5H5)] when R′= Pri. The photoiytic reaction of [W(SePh)(CO)3(η5-C5H5)] with CF3CCCF3 gives an alkyne derivative [W(SePh)(CO)(CF3C-CCF3)(η5-C5H5)]. A similar species [W(SC6H4Me-4)(CO)(CF3C-CCF3)(η5-C5H5)] was obtained from the thermal reaction of [W(SC6H4Me-4)(CO)3(η5-C5H5)] with F3C-CCF3via metallacyclic [[graphic omitted]C6H4Me-4}(CO)2(η5-C5H5)] and η2-vinyl [W{η2-C(CF3)C(CF3)C(O)SC6H4Me-4}(CO)2(η5-C5H5)] intermediates. In contrast, [[graphic omitted]Prn}(CO)2(η5-C5H5)] isomerises via an η2-vinyl analogue into the S-bonded vinyl ketone complex [[graphic omitted]Prn}(CO)2(η5-C5H5)] as a result of a 1,3 SR′ shift across the metallacyclic ring. Such a shift is also observed on thermal isomerisation of [[graphic omitted]R′}(CO)2(η5-C5H5)](R′= Me or Pri) but this proceeds via a avinyl intermediate [W{C(CO2Me)C(CO2Me)SR′}(CO)3(η5-C5H5)] to give both S- and O-metallated isomeric vinyl ketone derivatives. The mechanism of the shift is discussed in terms of three alternative pathways which are determined by the nature of the group R on the alkyne. The η2- vinyl complexes [W{η2-C(CF3)C(CF3)C(O)SR′}(CO)2(η5-C5H5)](R′= Me or Pri), on reaction with two-electron donor ligands L = CO, CNBut, PMe2Ph, or P(OMe)3, afford η3-lactone derivatives [W{η3-C(CF3)C(CF3)C(SR′)OC(O)}(CO)L(η5-C5H5)] as a result of cyclisation of the η2-vinyl ligand with a co-ordinated carbonyl group.

Analgesics of the 6,14-ethenomorphinan type. 6-deoxy-7 alpha-orvinols and 6-deoxy-8 alpha-orvinols.

6-Deoxythebaine (3) has been prepared as a precursor to C-6 alkyl substituted orvinols 15 and 17. The C-6 methyl group was introduced by addition of methyllithium to codeinone. Transformation of 6-methylcodeine to its 6-methyl ether and 1,4-elimination of methanol with potassium tert-butoxide in Me2SO then gave 6-deoxythebaine (3) in 49% overall yield. Diels-Alder addition of methyl vinyl ketone to this diene yielded four ketones: three regio- and stereoisomeric 6,14-endo-ethenomorphinans and one exo adduct. The major ketone isomer provided the set of C-19 diastereomeric orvinols 15 in which the pendant carbon has the 7 alpha configuration. Regioisomeric ketone 8, in which the acetyl group is at C-8, was formed in 3% yield and was similarly converted to the corresponding orvinols 17. Orvinol (R)-15 (R at C-19) is an analgesic of very high potency, 2200 times that of morphine; regioisomeric orvinols 17, in which the pendant tertiary alcohols are on C-8, are much less potent. The higher activity of the C-6 methyl and methoxyl analogues (R)-15 and (R)-22 relative to hydrogen-substituted (R)-19 indicates that C-6 alkyl substitution enhances analgesic potency.

Specific reciprocal methyl/hydrogen transfer reactions and hydrogen exchange processes between aryl rings in crowded ketone cation radicals

In distinct contrast to metastable triarylethenol cation radicals, the corresponding isomeric ketones not only show site-specific reciprocal methyl/hydrogen migration but, in addition, some of them undergo hydrogen exchange reactions between the various aryl rings prior to dissociation. A brief discussion is presented for H 2O loss from ionized 1,2,2-trimesitylethanol and the gas-phase chemistry of the resulting trimesitylethene cation radical.

Reactions of coordinated cyclic polyolefins. Regio- and stereo-specific cycloadditions of ketenes and tricarbonyl(η 4-polyene)iron complexes. Structural evidence for a concerted 2 + 2 mechanism

The cycloaddition of ketenes R 1R 2CCO (R 1 = Me, R 2 = Ph; R 1 = R 2 = Ph; R 1 = Ph, R 2 = p-tolyl) (III) and tricarbonyl(η 4-cycloheptatriene)iron (II) at room temperature gave regiospecifically the cyclobutanones IV, in which the carbonyl is bonded to the uncoordinated terminal of the conjugated triene. Tricarbonyl(η 4-cyclooctatetraene)iron, VI, similarly reacts with dipenylketene to give the regioisomeric cyclobutanone VIII. Single crystal X-ray analysis of tricarbonyl[(η-2,3,4,5)-9-methyl-9-phenylbicyclo[5.2.0]nonan-2,4-dien-8-one]iron (IVa) confirmed the presence of the phenyl group at the endo position, providing a stereochemical evidence for a concerted 2 s + 2 a cycloaddition mechanism. The adducts IV undergo cyclobutanone ring cleavage catalyzed by acid to give the isomeric ketones VII. The diaryl adducts (IVb and IVc) rearrange thermally to the σ,π-allylic complexes IX, which may also be obtained directly upon heating cycloheptatriene complex II and the diarylketenes.

A novel radical induced rearrangement of the caryophyllene skeleton

The addition of an acetyl radical on caryophyllene leads to formation of the four isomeric ketones 5-8 involving a novel rearrangement of the caryophyllene skeleton.

Determination of carbonyl group position in triamantanone by 13C-NMR Spectroscopy

Z. Kafka, L. Vodi~ka, and M. Hajek Laboratory of Synthetic Fuels, Institute of Chemical Technology, CS-16628 Praha 6, CSSR Bestimmung der Stellung der Carbonylgruppe in Triamantanon dureh laC_NMR.Spektroskopie This paper deals with the determination of the carbonyl group position in triamantanone using ~3C-NMR spectroscopy with application of the additivity rule derived from the chemical shifts of diamantane and triamantane. Triamantane is the third member of the diamondoid hydrocarbon series. In triamantane, similarly as in adamantane and diamantane, the secondary position is less reactive than the bridgehead one [1]. Therefore, only tertiary substituted triamantane derivatives were prepared up to this time [2]. We studied the oxidation of triamantane by means of sulphuric acid [3]. The compounds separated from the reaction mixture were supposed to be carbonyl bearing compounds according to the IR spectra. The separation of the reaction mixture yielded the compounds which were studied by IaC-NMR spectroscopy 9 Experimental. Triamantanone (Fig. 1) was prepared by heating triamantane with 96 % sulphuric acid [4]. The product included two isomeric ketones in the ratio 3 : 1 and the main component was concentrated by recrystallisation from hexane. 13C-NMR spectra were measured on the Tesla BS 567 "~ spectrometer at 25.14MHz. A 10-mm tube was used; the II concentration of the compound was 100 rag/1.5 ml CDC13 with .e tetramethylsilane as internal standard 9 Broadband, SFORD and APT spectra were used for the assignment of the signals. The precision of the measurement of the chemical shift was _+ 0.1 ppm. II Results and Discussion 9 The presence of a carbonyl group in the oxidation product of triamantane was verified by IR-spectroscopy (v max. 1,700cm-I); the presence of the

New rearrangement in the o-carbomethoxydiazoacetylpyridine series

NEW REARRANGEMENT IN THE o-CARBOMETHOXYDIAZOACETYLPYRIDINE SERIES V. G. Kartsev, S. V. Chapyshev, UDC 547.822.7'824'826.1'26'834.2:541.621.2 N. S. Yashina, and V. S. Petrosyan We have observed that a rearrangement occurs in the reaction of o-carbomethoxydiazoace- tylpyirdines with sodium methoxide; the product of this ~earrangement is the isomeric diazo ketone. Thus diazo ketone I at room temperature in methanol in the presence of 5% CHsONa solu- tion is converted to the isomeric diazo ketone III. In turn, the addition of sodium methox- ide to a methanol solution of III leads to the formation of diazo ketone I.

Oxidation of saturated hydrocarbons by tert-butyl hydroperoxide in the presence of transition metal compounds

1. The acetylacetonates of V(III), V(IV), Cr(III), and Co(II), the stearates and caproates of Cu(II), Mn(II), Fe(II), and Co(II), and the carbonyl derivatives of Cr, Mn, and Rh catalyze the selective oxidation of nonane, cyclohexane, and diphenylmethane by tert-butyl hydroperoxide to the isomeric ketones. 2. tert-Butoxyl radicals do not take part in the oxidation of hydrocarbons.

ChemInform Abstract: CONCERNING THE STEREOCHEMICAL COURSE AND MECHANISM OF THE PHOTOCHEMICAL 1,3‐ACETYL SHIFT IN A β,Γ‐UNSATURATED KETONE. PRELIMINARY COMMUNICATION

AbstractDie zwischen ‐45 und +50°C beobachtete Isomerisie‐ . rung der Ketone (I) und (II) wird von einer temperaturunabhängigen Änderung der Enantiomerenverteilung begleitet, die einer Racemisierung durch Rekombination von sekundären Singulett‐ und Triplett‐Radikalpaaren zugeschrieben wird.

Concerning the Stereochemical Course and Mechanism of the Photochemical 1,3‐Acetyl Shift in a β,γ‐Unsaturated Ketone. Preliminary Communication

AbstractEnantiomerically enriched samples of 1,2‐dimethyl‐3‐(2H3)methyl‐2‐cyclopentenyl (1) and 1‐(2H3)methyl‐2,3‐dimethyl‐2‐cyclopentenyl methyl ketones (2) have been irradiated at 313 nm in methanol in the temperature range +50 to −45°. The 1,3‐acetyl shift, which interconverts the two isomeric ketones, occurs with a small change in the enantiomeric composition and independently of temperature in the range studied. This change corresponds to an upper limit of approximately 20% reaction with racemization. It is proposed that reaction occurs from both the S1(n, π*) and T2(n, π*) excited states with stereospecific reaction from S1 (rapid primary geminate recombination of a singlet radical pair, with a possible contribution by a concerted 1,3 shift) dominating throughout the temperature range, but with the proportion of reaction from T2 increasing as the temperature is lowered. The racemization results from secondary geminate recombination of the singlet and triplet radical pairs and the random recombination of free radicals. Viscosity effects are proposed to explain the independence of the racemization on temperature.