Nitroxydes—XLVII: Nitroxydes isoquinuclidiniques

5 and 7 substituted 1,3,3-trimethyl isoquinuclidines are prepared by the action of ammonia on piperitenone and 4-methyl piperitenone. Reduction of 1,3,3-trimethyl 5-isoquinuclidone, and the different alcohols obtained are described. The nitroxydes obtained by oxidation of these amines exhibit long range couplings.     

Organophosphorus compounds—XVI: The reaction of phosphite esters with vicinal triketone monohydrates

Trialkyl phosphites react with the monohydrates of 1,2,3-indantrione (ninhydrin) (VII) and 1,3-diphenylpropanetrione (VIII) to give the corresponding phosphate derivatives XIa–c and XVIIIa–c. The same compounds are obtained upon reacting VII and/or VIII with the proper dialkyl hydrogen phosphite. The trialkyl phosphites cause the quantitative reduction of perinaphthindantrione (IX) and/or its monohydrate (X) producing dihydroxy-peri-naphthindenone (XXI). On the other hand, dialkyl hydrogen phosphites add to IX (or X), yielding compounds XXIIa–c.     

Heterocyclic N-glycosyl derivatives—XIII: Reaction of 6-chloropurine and benzotriazoles with acetylated glycals

Acid-catalysed reactions of tri-O-acetyl-D-glucal with benzotriazole, 5,6-dimethylbenzotriazole, 5,6-dichlorobenzotriazole and 6-chloropurine have been found to give anomeric mixtures of the corresponding 2′,3′-unsaturated N-glycosyl derivatives with the α-anomers preponderating. When tri-O-acetyl-D-galactal was used the 3′,4′,6′-tri-O-acetyl-α- and β-D-lyxo-hexopyranosyl nucleoside analogs were obtained. The conformation and anomeric configuration of all the N-glycosyl compounds obtained were assigned by NMR studies.     

Organophosphorus compounds—XV : The reaction of trivalent phosphorus with halo substituted p-quinoneimines

Trimethyl and triethyl phosphites react with quinoneimine IV, in aprotic and protic solvents to produce compounds V, VI and VII. The outcome of this reaction depends on the experimental conditions. Triphenyl phosphite, triphenyl-phosphine and phosphorous acid cause the quantitative reduction of IV to VII. A mechanism for the reaction is presented which accounts for the experimental results.     

Trimethylsilyl-substituted diazoalkanes : I. Trimethylsilyldiazomethane

Trimethylsilyldiazomethane was prepared by the action of aqueous KOH on nitroso-N-(trimethylsilylmethyl)urea. The spectroscopic properties of this stable, greenish-yellow liquid which can be isolated by gas chromatography are discussed. Its reaction with acetic acid gives the expected CH₃CO₂CH₂SiMe₃ in addition to SiC cleavage products, CH₃CO₂CH₃ and CH₃CO₂SiMe₃. Products of the 1,3-dipolar addition of Me₃SiCHN₂ to activated olefins were not very stable, and only the adduct with acrylonitrile was isolated as a pure material Trimethylsilyldiazomethane undergoes Me₃SiCH transfer to olefins, giving trimethylsilyl-substituted cyclopropanes, in the presence of CuCI in benzene, but other products are formed as well. Thus such a reaction with cyciohexenegave anti-7-trimethylsilylnorcarane (65%), syn-7-trimethylsilylnorcarane (7%), cis- and trans-l,2-bis(trimethylsilyl)ethylene (9% and 13%, respectively), and an unidentified Me₃SiCH trimer (2.3%).     

Terpenoids and related compounds—XXI : The structures and stereochemistry of putranjivic acid and putranjic (putric) acid

The structures IIIa and IVa suggested for putranjic and putranjivic acids respectively have been confirmed by the synthesis of methyl putranjivate (IVb) from friedel-3-ene (IX). Putranjic acid has been shown to have S-configuration (IIIa) at C₂.     

Photoreactions of aromatic compounds—XXVI : Photoinduced reactions of biphenyl and biphenyl derivatives with cyanide ion

The photoreactions of a number of biphenyl derivatives, in particular nitrobiphenyl derivatives, with cyanide ion have been investigated. Photosubstitution by cyanide ion has been found to predominate; photoreduction is not observed. In some cases (4-nitrobiphenyl, 4,4′-dinitrobiphenyl, 3-nitrobiphenyl and similar compounds) the behaviour can be rationalized on the basis of analogy to the pattern of photocyanation of biphenyl itself (preference for substitution of the 4-position). 2-Methoxy-4-nitrobiphenyl and 2-methoxy-5-nitrobiphenyl on irradiation reacted with cyanide ion following the pattern of the nitroanisoles rather than that of the nitrobiphenyls not containing a methoxy substituent. In photo-excited 2,4,6-trimethylbiphenyls the favoured position for attack by cyanide ion appears to be at the 3-position, i.e. in the methyl substituted ring.     

Studies on the syntheses of heterocyclic compounds—CDLXXXIV : One-step synthesis of dibenzoindolizinium salt and phenolic aporphine by benzyne reaction

An indisputable benzyne reaction of 1-(5-bromo-2,4-dimethoxybenzyl)-1,2,3,4-tetrahydro-7-hydroxy-6-methoxy-2-methylisoquinoline (1) with NaNH₂ in liquid NH₃ afforded 1-hydroxy-2,8,10-trimethoxy-6-methylaporphine (4) and 5,6,12,12a-tetrahydro-2-hydroxy-3,9,11-trimethoxy-7-methyldibenzo[b,g]indolizinium salt (6).     

Solanum-alkaloide—SCVI: Synthese von solafloridin und 25-iso-solafloridin

3β,16α-Diacetoxy-20-(5-methyl-2-pyridyl)-pregna-5,20-diene (2) available from 3β-acetoxy-pregna-5,16-dien-20-one (1) was transformed into solafloridine (11) and 25-iso-solafloridine (13).     

Etudes photochimiques—XIV : Photoreactions des methylisothiazoles

Photorearrangement of methylisothiazoles proceeds via a zwitterion and the amount of rearranged products increases with solvent polarity. When irradiated in the presence of primary amines, 3-methylisothiazole which is the less isomerised, and 5 methylisothiazole give charge transfer complexes. The amine cation radical is hydrolysed to an aldehyde. 4-Methyl isothiazole does not lead to a charge transfer complex.     

Tellurium in organic chemistry—I : A novel synthesis of biaryls

Treatment of bis(aryl)tellurium dichlorides or diaryl tellurides with degassed Raney nickel readily affords the corresponding biaryls. The bis(aryl)tellurium dichlorides were prepared from TeCl₄ and the appropriate aromatics, with or without a Lewis acid as a catalyst, depending on the reactivity of the aromatic. The diaryl tellurides were prepared by reduction of the dichlorides with hydrazine. Attempts to prepare unsymmetrical dichlorides frequently resulted in exchange reactions (RTeCl₃ + R′H → R′TeCl₃ + RH).     

Rotational isomerism—XIII : Rotational isomerism in furfuraldehyde

The equilibrium between the cis and trans isomers of furfuraldehyde has been studied by measuring the stereospecific coupling constants between the aldehyde and ring protons in various solvents. These values when combined with the observed values of the couplings in the individual conformers at low temperatures give the energy difference between the cis and trans forms in these solvents. These values together with other previous measurements demonstrate the large solvent effect on this equilibrium. E(cis)-E(trans) is +1·5 kcals/mole in the vapour, much smaller in non-polar solvents (+0·3 kcals/mole in CF₂Cl₂), ca 0 in CHCl₃ and becomes negative in polar media (−1·0 kcals/mole in the pure liquid). This solvent dependence is given a quantitative explanation in terms of a known theory of solvation.     

Chemistry of leucomycin-X: Conformational studies on leucomycin

The conformation of leucomycin, a macrolide antibiotic with a 16-membered ring lactone, was examined in solution by IR, NMR and CD spectral analysis. The IR reveals that the five hydroxyls are all involved in intramolecular H-bonding. The NMR of the 16-membered ring lactone forming the aglycone shows that the acetyl-carbonyl at C-3, the allylic proton at C-11 and the aldehyde proton are in close proximity on the lactone ring. CD studies suggest that the conformation of the 16-membered ring lactone, especially around the lactone, is mobile and solvent dependent.     

Metal carbonyl-trifluorophosphine systems : X. Mono-and triruthenium carbonyls

Triruthenium dodecacarbonyl reacts with high pressure PF₃ or with PF₃/CO mixtures to yield two series of compounds. At high PF₃ pressures, the mononuclear species Ru(PF₃)_x(CO)_5−x (x = 5, 4 and 3) are the main products with only traces of Ru(PF₃)₂(CO)₃ and Ru(PF₃)(CO)₄ being found. With high carbon monoxide pressure and less PF₃, the species Ru₃(PF₃)_y(CO)_12−y (y = 0–6) are the main products. It is seen that Ru₃(CO)₁₂ can have up to six CO groups replaced sequentially before the cluster is broken followed by the formation of the mononuclear species. The evidence shows that the Ru(PF₃)_x(CO)_5−x species are stereochemically non-rigid.     

MO-berechnungen an heterocyclen—VII : Tautomerieprobleme an substituierten 1,3,8-triazaindolizinen

The electronic spectra of some derivatives of 5-hydroxy-7-methyl-1,3,8-triazaindolizine have been calculated with the PPP-procedure. With the electronic spectra and heats of atomization the tautomeric structures of the compounds 6-ch]or-5-hydroxy-7-methyl-1,3,8-triazaindolizine, 6-brom-5-hydroxy-7-methyl-1,3,8-triazaindolizine, 6-carboxy-5-hydroxy-7-methyl-1,3,8-triazaindolizine, 2-carboxy-5-hydroxy-7-methyl-1,3,8-triazaindolizine, 2-mercapto-5-hydroxy-7-methyl-1,3,8-triazaind and 5-amino-7-methyl-1,3,8-triazaindolizine are discussed. The possible structures of the compounds 5-hydroxy-7-methyl-1,3,8-triazaindolizine, 5-hydroxy-7-methyl-1,2,8-triazaindolizine and 5-hydroxy-7-methyl-1,2,3,8-tetrazaindolizine depending on the pH-value of the solution have been investigated.