Recherches dans la série des cyclitols,XL. Préparation de cyclopentane-triols et de cyclopentène-triols et -diols

Two as yet unknown cyclopentene-triols have been prepared. The replacement of the halogen of cyclopentene derivatives brominated in the allylic position has been investigated. In the presence of dimethyl sulfoxide and sodium hydrogen carbonate, the bromine of some of the above mentioned allylic derivatives or the tosyloxy group of a dibenzoyloxy-monotosyloxy-cyclopentane derivative is replaced by a hydroxyl group without formation of any keto compound. The mechanism of action of the substitution agents is discussed.     

Recherches dans la série des cyclitols,XLI. Synthèses de deux cyclopentane-pentols

Two new cyclopentane-pentols, namely the 1, 2, 3, 4/5- and 1, 2, 3/4, 5-isomers have been prepared by hydroxylation of the three 3, 4, 5-trihydroxy-1-cyclopentenes. The stereoselectivity of some hydroxylating agents is discussed.     

Recherches dans la série des cyclitols XXXVII Etude par spectrométrie de masse

Low resolution mass spectra of cyclohexane-triols, -tetrols, -pentols and -hexols and of some of their deuterium labelled derivatives have been measured. The results indicate that for some geometrical isomers quantitative differences between ion intensities are significant, allowing to deduce the stereochemistry of the molecule from its mass spectrum. In all these compounds the electron impact induced elimination of water occurs mainly by interaction between OH groups. There is a correlation between the relative abundance of (M – H₂O)⁺ and (M ?2 H₂O)⁺ ions and the number of axial hydroxyls in the more stable conformation of the molecule. Difficulties encountered in deducing fragmentation patterns, and determination of number and position of deuterium atoms in the molecule of ms-inositol are discussed.     

Recherches dans la série des cyclitols XLIV. Synthèses de cycloses dérivés du cyclopentane

The conversion to free ketoses by transketalisation of ethylene-ketal and/or isopropylidene derivatives of polyhydroxy-cyclopentanones has been investigated. The preparation of 2, 3-dihydroxy-cyclopentanone and of 2, 3-dihydroxy-cyclopentenone has been described.     

Recherches dans la série des cyclitols XXXVIII Etudes conformationnelles de dérivés cyclopenténiques disubstitués-3, 5

Cyclopentenones substituted in position 4, and 3, 5-cis or -trans disubstituted cyclopentenes have been studied by NMR. and by IR. spectroscopy. Cyclopentenone derivatives and cyclopentene derivatives adopt a quasi-coplanar and an envelope conformation, respectively. The preferential orientation of the substituents has been established according to their nature and to the solvents by correlation to the vicinal and the long-range coupling constants.     

Recherches dans la série des cyclitols XLII. Synthèses de cyclitols tout-cis dérivés du cyclopentane; préparation des cyclopentane-tétrol et - pentol tout-cis

All-cis cyclitols derived from cyclopentane have been prepared in two ways: (i) by LiAlH₄ reduction of all-cis epoxypolyos; (ii) by dimethyl sulfoxide treatment, in the presence of sodium hydrogencarbonate, of brominated derivatives containing a neighbouring benzoyloxy group; under these conditions, the halogen is replaced by a cis-oriented hydroxyl group. Thus all-cis cyclopentane-tetrol and -pentol have been prepared; their configuration has been confirmed by NMR. spectroscopy.     

Recherches dans la série des cyclitols XLIII. Sur des éthylène-cétals de cétoses dérivés du cyclopentane

The synthesis of a series of keto derivatives of cyclopentane is described. The configurations of these derivatives have been determined by chemical methods and verified by IR. and NMR. spectroscopy. The preferred conformation of the cyclopentane part of the molecule has been established by the study of intramolecular hydrogen bonds and the values of the coupling constants J_{H? C? OH} and J_{H, H}.     

Recherches dans la série des cyclitols XLVI. Actions de diazoalcanes sur la pentahydroxy-2,4,6/3,5-cyclohexanone et sur son dérivé penta-O-acétylé II. Etude de pentahydroxy-alkyl-C-cycloheptanones

On treatment with higher diazoalkanes, 2,4,6/3,5-penta-acetoxy-cyclohexanone (penta-O-acetyl-myo-inosose-2 or -scyllo-inosose) afforded by ring expansion all-trans-penta-acetoxy-C-alkyl-cycloheptanones, which by deacylation were converted to hemiacetals. The reactions with diazoalkanes of the penta-acetoxy-inosose in the presence of aluminium chloride and of the free inosose in water solution have also been studied. The structure, the configuration, and, in some cases, the conformation of the new compounds have been established and some of their reactions have been investigated. The mechanisms of formation of the ring expansion products and of the concomitant spiro-epoxides have been discussed.     

Recherches dans la série des cyclitols XLV. Action des diazoalcanes sur la pentahydroxy-2,4,6/3,5-cyclohexanone et sur son dérivé penta-O-acétylé. I. Etude des spiro-époxydes

On treatment with diazomethane, 2,4,6/3,5-penta-acetoxy-cyclohexanone(penta-O-acetyl-myo-inosose-2 or -scyllo-inosose) gave only a spiroepoxide. In contrast, replacement of diazomethane by higher diazoalkanes furnished a mixture of alkylspiroepoxides and of ring expansion products (cycloheptanone derivatives). The configuration and the reactions of the spiro-epoxides have been studied.     

Synthèse de flavones et de xanthones dans la série du benzo[4,5]thiophène

We describe the first synthesis of 2-arylbenzo[4,5]thieno-[2,3-b]pyran-4-one and of 2-arylbenzo [4,5] thieno [3,2-b] pyran-4-one, from benzo [4,5] thiophene and we have extended these cyclizations to obtain the heterocyclic analogs of the xanthones.     

Recherches dans la série de la quinoléine: Préparation et oxydation du chlorhydrate de (1-quinoléinio)acétate

Reaction of quinoline with chloroacetic acid yields N-carboxymethyl-quinolinium chloride ( 1 ) (75%), which is oxidised by K₃Fe(CN)₆ in the presence of a base to N-carboxymethyl- 2 -quinolone ( 2 ) (70%). If 2 is heated in pure form at 300°, 1,3-Bis(2-quinolon-1-yl)acetone ( 4 ) (43%) is obtained; the expected N-methyl-2-quinolone ( 5 ) is formed by decarboxylation of 2 in benzyl benzoate at 275° (34%).     

Etude par RMN 13C de quelques époxydes exo et endo dans la série du bicyclo[2.2.1]heptane

The ¹³C NMR spectral study of epoxy bicyclo [2.2.1]-heptanes reveals a strong influence on the chemical shift of the bridging ¹³C, due to the endo or exo orientation of the heterocyclic ring. The difference between the ¹³C and ¹H Δδ shows that the observed results cannot be explained by the ring current alone.     

Prototropie et synthèses nouvelles dans la série des dihydro-5,6 hydroxy-4 pyrones-2 et pyridones-2

The multistep catalytic reduction of 6-methyl-4-hydroxy-2-pyrone allows isolation of two intermediate compounds: the biologically active parasorbic acid ( 5 ) and the 6-methyl-5,6-dihydro-4-hydroxy-2-pyrone ( 2 ). The desmotropic keto-enol equilibrium lies on the enol side, with the 4rhydroxy structure. Primary arylamines readily react with 2 , leading to corresponding 2-pyridones 8 ; with methylamine, the aliphatic intermediate 7 resulting from ring attack at the 2 position can be isolated. Also further functionnalization of both dihydropyrone and 2-pyridone is possible by selective bromination at position 3.     

Recherches sur le benzofuranne. LVI. Synthèses dans la série de l'Euparone par acétylation de benzofurannes acétylés et méthoxylés sur l'homocycle

Unsubstituted benzofuran derivatives acetylatcd and methoxy-lated on the benzenoid moiety can be further acetvlated either on the benzene or on the furan ring - with or without demethylation depending upon the different cases. A series of new isomers of Euparone (2,5-diacetyl-6-hydroxybenzofuran) and its corresponding ether has thus been formed.     

Utilisation de la RMN a champs forts dans la série du norbornène: triméthylsilyl-endo-3 bicyclo (2.2.1) heptène-5

High field NMR spectroscopy, double resonance and INDOR experiments are used for unambiguous assignment of the endo configuration of 3-trimethylsilyl-5-norbornene. Chemical shifts and coupling constants have been accurately determined and tested by computer simulation. Some ‘non W’ long range couplings are demonstrated.     

Etude par spectrométrie de masse des cyclopenténols,cyclopentène-diols-3,4 et cyclopentène-triols-3,4,5

The mass spectra of cyclopentene-1-ol-3, -1-o1-4, those of cis- and trans-cyclopentene-3,4-diol and of the three stereoisomers of cyclopentene-3,4,5-triol have been studied. Decomposition modes based upon results obtained using deuterium labelled analogues are discussed.     

Diastéréotopies dans la série du benchrotrène

¹H and ¹³C spectra of mono-and disubstituted (benzene)-tricarbonylchromium complexes have been analysed. The influence of the substituents is discussed and special attention is paid to the diastereotopy resulting from different types of chirality. The racemic pseudosymmetric isomer and the two meso pseudoasymmetric isomers of the glycols (OC)₃CrC₆H₄(CHOHCH₃)₂ are compared. The stereochemical requirements are also examined.