On the question of allene formation from tricyclic cyclopropylidenes

The carbenoid or carbene derived from $\text{8}$ undergoes dimerization or trapping with DPIBF. The allene mechanism previously proposed was made doubtful by the finding that stereoisomeric carbenes

and

give stereoisomeric products without crossover.     

Double bridgehead olefins via pyrolysis

Pyrolysis of diacetate $\text{5}$ produced 3 major products, $\text{6}$–$\text{8}$. The most reasonable pathway to these products, supported by deuterium labelling studies, is via double bridgehead olefins

and

.     

A direct synthesis of 1,3-bis(bromomagnesio)propane

Careful addition of 1,3-dibromopropane

to magnesium in Et₂O yields 1,3-bis(bromomagnesio)propane

which is purified via “magnesacyclobutane”

. Reactions of

with H₂O, CO₂, HgBr₂ and Me₃SnCl are reported. MgBr₂ catalyses the decomposition of

to allylmagnesium bromide

.     

The preparation of fluxional tetrahydrides, (R  H or Me) and their reactions with CO,ButNC or HBr

The cyclometallated monohydrides

(R  H or Me) react with NaOPrⁱ/PrⁱOH/H₂ to give fluxional tetrahydrides, probably

. These are highly fluxional having magnetically equivalent hydridic hydrogens, even at ---100°C. When treated with HBr,

, gives

and with CO it gives a mixture of complexes which are probably

(2 isomers) and

. When treated with Bu^tNC this tetrahydride undergoes similar reactions but another (major) product is formed which appears to be binuclear and fluxional and is probably of type

, with four bridging hydrogens.     

A new stereocontrolled synthesis of d-ring aromatic steroid

D-Ring aromatic steroid (

having 19-methyl and C₆-nitro group has been stereo-selectively synthesised by an intramolecular cycloaddition of the $\text{o}$-quinodimethane ($\text{A}$) derived thermally from 5-acetoxy-2-[2-(1-cyano-4-methoxybenzocyclobutenyl)-1-nitroethyl]-1-ethenyl-1-methylcyclohexane (

).     

Synthesis and intramolecular charge-transfer interaction of o-tropyliobiphenyl tetrafluoroborates

A series of o-tropyliobiphenyl tetradfluoroborates

has been synthesized. Evidences are presented to show that

exhibit strong intramolecular charge-transfer interaction between tropylium ion and remote aryl ring. The structure of

was determined by single crystal X-ray diffraction study.     

The preparation of perfluorinated esters of fluorine containing tertiary alcohols

The reaction of an aromatic lithium reagent, LiR, with a perfluoroacid anhydride (RfCO)₂O, in ether solution at low temperatures, produces esters of composition

in addition to the expected ketone

. Mixed esters of composition

may be prepared by starting with a ketone

and reacting with a lithium reagent LiR followed by perfluoroacid anhyride (RfCO₂O. Hydrolysis of the esters provide a convenient route to trertiary alcohols of composition Rf(R) ₂COH.     

Some chlorine fluorosulfonate and peroxydisulfuryl-difluoride reactions

Chlorine fluorosulfonate adds exceptionally easy not only to various alkenes, perfluorobenzene, but to alkynes too

The addition of peroxydisulfuryldifluoride to alkyl- and perfluoroalkyliodides leads to unstable adducts, which decompose with the formation of alkylfluorosulfonates and iodine fluorosulfonate; the latter was trapped with fluoroalkenes

The use of ClOSO₂F allows to substitute selectively for the fluorosulfonate group the chlorine atom in monochloroacetic acid esters as well as the fluorine atom in hexafluoroacetone N-fluoroimine

ClOSO₂F serves as an exceptionally active chlorinating reagent for fluorinated alcohols, nitrosocompounds, perfluoroacid amides and particularly for benzene

The reaction of (OSO₂F)₂ with perfluoroacid amides leads to the corresponding N,N-bis(fluorosulfonate)amides, which easily rearrange into alkylfluorosulfonates

The hypochlorites of fluorinated alcohols are stable enough and they, similarly to ClOSO₂F, are able to add to alkenes, fluoroalkenes (but not to perfluoroisobutylene), bis(trifluoromethyl)ketene, trifluoromethylisocyanate and perfluoronitriles

The fluorosulfonatoacetic acid esters are unstable at the ambient temperature, but they can be widely used in situ as a very effective alkylating reagents

     

Electrogeneration of triplet states of intramolecular anthracene-amine systems

In the electron transfer between the cation radicals

of the amine moiety of four intramolecular anthra cene-amine systems and the anion radicals B^XXX of some heterocyclic and carbonyl compounds in acetonitrile/toluene, the triplet state of the anthracene moiety

is formed. As intermediates in this process, intramolecular and intermolecular triplet exciplexcs

or

and

or

are discussed.     

Electrokinetic phenomena in porous membranes: Determination of phenomenological coefficients and transport numbers

Electrokinetic phenomena in porous membranes were studied in the framework of the linear thermodynamics of irreversible processes. Phenomenological coefficients of two commercial porous membranes were determined. The variation of these coefficients with the different concentrations of NaCl used was also studied. Onsager's reciprocal relationship between cross-coefficients holds within the limits of experimental error.Membrane potentials were measured at concentrations ranging from 10^?3M to 75 X 10^?3M. The apparent transport number of the cation,

, was calculated from the diffusion potential expression. An electrometric method was used to obtain the true cation transport number,

, and the water transport number,

, for different solution concentrations, ranging from 15 x 10^?3M to 75 x 10^?3M. The true transport number of the cation,

, was also determined, taking into account water transport across the membrane. A good agreement was found between

and

values.     

Doping-addition of arylsulfenyl chlorides to the tricyclo[4,2,2,02,5]deca-3,7,9-triene system: skeletal rearrangements and serendipitious products

“doping-addition” of 2-NO₂C₆H₄SCl to the tricyclo[4,2,2,0^2,5]deca-3,7,9-triene system

occurs to give unusual products: (i) rearranged caged cyclopropane

and (ii) the stable cross-perchlorate

.     

Monofluoration stereoselective par le phenyltetrafluorophosphorane (PhPF4) Part. II. Application a la synthese des isomeres thréo et érythro des alkyl-2 fluoro-3 phenylpropanoates de methyle. Analyse conformationnelle par R.M.N. de 19F et 1H.

The stereoselective fluorination of four couples of diastereoisomeric 2-alkyl 3-hydroxy 3-phenylpropanoic methyl esters

by the reaction of the phenyltetrafluorophosphorane with the corresponding trimethylsilylethers derivatives

is described. The structure of the 2-alkyl 3-fluoro 3-phenyl propanoic methyl esters

obtained quantitativly has been determined unambiguously by NMR analysis. ¹⁹F NMR results permit us to determine the relative populations of the rotamers for each of the isomers threo and erythro.     

Determination de l'enthalpie de formation standard du tetrafluorure de tellure par calorimetrie de combustion dans le fluor et par calorimetrie de reaction

The standard enthalpy of formation of tellurium tetrafluoride has been determined: by combustion in fluorine:

by reaction in a normal solution of soda:

     

Diversity of the gramicidin a spatial structure: two-dimensional 1H nmr study in solution

Theoretical consideration reveals a unique relationship between NMR spectral parameters and possible types of the gramididin A spatial structure. By means of two dimensional NMR spectroscopy four distinct species were detected simultaneously in ethanol solution. Comparison of experimental data and theoretical conclusions demonstrates that species 1 and 2 are left-handed parallel double helices

differing in relative arrangement of the two polypeptide chains within the dimers, species 3 is left-handed antiparallel double helix

, and species 4 is a mirror image of species 1, i.e. right-handed parallel double helix

. The results are compared with those on spatial structures of the peptide in complex with cesium (right-handed antiparallel double helix

) and of the gramicidin A transmembrane ionchannel (N-terminal to N-terminal single-stranded dimer

).     

Further evidence for the intramolecular charge-transfer interaction between tropylium ion and remote benzene rings in 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborate and its methyl derivatives

A series of 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborates

has been prepared. The intramolecular charge-transfer interactions in

were confirmed by their UV spectra and pK_R+ values. As a model compound 1,2,3,4-tetrahydro-1,4-(1,2-tropylio)naphthalene tetrafluoroborate ($\text{5}$)_was also examined.     

Synthesis of fluoroamines,fluoroketones and difluoroamines

Aziridines $\text{1}$ and 2H-azirines $\text{2}$ are now very easy to prepare. These small rings are transformed in fluoroamine and fluoroketone by reaction with HF liquid or Olah reagent. Different compounds $\text{3}$, $\text{4}$ or $\text{5}$ are obtained. A lot of examples will be described.

a) Configuration of $\text{3}$ depends of the reagent (HF liquid or Olah reagent):

Mechanism of this reaction will be discuss.b) Some aziridines give a mixture of fluoroaminoisomers. Example:

With R = H, a mixture of $\text{6}$ (65 %) and $\text{7}$ (35 %) is obtained. It is possible to form quantitatively one regioisomer only, by using activating group on the nitrogen (R  CO₂tBu).c) From azirine $\text{2}$, formation of $\text{4}$ or $\text{5}$ dépends of the nature of substituents at carbon C-2. If a carbocation can be easily formed at C-2 carbon, only fluoroketone $\text{4}$ is isolated.Difluoroamine $\text{5}$ are obtained if carbon C-2 is a secondary or primary one. By using a modified Olah's reagent, we improve the yield.Application of this results on synthesis of fluorosteroïd compound will be presented:

     

The composition of the evolved gases from the thermal decomposition of certain metal sulfates

By the use of TG—MS, the thermal dissociation of anhydrous CuSO₄ and Al₂(S0₄)₃ was found to proceed according to the reactions:

followed by the reactions:

No SO₃ was indicated in the dissociation of alunite. The sulfate ion appears to dissociate by at least two different mechanisms although the parameter which controls the mechanisms has not been elucidated.     

Synthesis of (±)-lineatin,the unique tricyclic pheromone of Trypodendron lineatum (olivier)

(+-)-3,3,7-Trimethyl-2,9-dioxatricyclo[4.2.1.0^{4, 7}]noname

and (+-)-3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.0^{4, 7}] nonane

were synthesized. The latter was shown to be (+-)-lineatin, an ambrosia beetle pheromone.     

Reaction of tellurium(iv) with dithizone

With an excess of dithizone over tellurium, the extraction of Te(IV) from 1 M perchloric acid solutions into a carbon tetrachloride solution (o) of dithixone follows the relation

When the acidity is varied, again with a sufficiently large excess of dithissone, the following relation seems to be approached;

(μ=1.0).