Synthese de la phenyl-2-dimethyl-4,5-phosphorine a partir du benzyl-1-dimethyl-3,4-phosphole

1-Benzyl-3,4-dimethylphosphate

-$\text{1}$ is converted into 2-phenyl-4,5-dimethyl-λ₃-phosphorin

-$\text{2}$ through 1,2-dihydro-λ₅-phosphorines

$\text{3}$ and

$\text{s}$.     

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

.     

Sensitized photochemical reactions of some silyl-1,3-butadienes: Synthesis of 2,2,4-trimethyl-3-methylene-2-silabicyclo [2.1.1]Hexane

The photolysis of 2,4,4-trimethyl-4-sila-3-methylene-l,5-hexadiene

yielded 2,2,4-trimethyl-3-methylene-2-silabicyclo[2.1.1]hexane as the only volatile photoproduct in high yield. However, 2,4,4-trimethyl-4-sila-3-methylene-1,6-heptadiene

was found to be photochemically non-reactive under identical reaction conditions, and the 1-substituted butadienes (VI) and (VIII)

underwent cis-trans isomerism on photolysis.     

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 (

).     

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.     

Sterospecific synthesis of 1,2-difluoroethylenes

So far, no general and simple synthetic method was available to prepare 1,2-difluoroethylenes $\text{1}$ bearing only one hydrocarbon substituent.We developed such a method, using the steps outlined in the following sequence :

The alkenes $\text{1}$, whose configuration was always found to be Z could be epoxidized into cis 1,2-difluoroepoxydes.The different steps will be detailed and discussed.     

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

     

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.     

Preparation and properties of some cyclic germanium 1,4-cyclohexanediolates

Colourless liquids of cyclic compounds of the type:

have been prepared by reactions of dibutylgermanium dichloride with cis-1,4-cyclohexanediol or cis,cis,cis-2,5-di-tert-butyl-l,4-cyclohexanediol, in benzene in the presence of a hydrogen halide acceptor.Under similar conditions germanium tetrachloride gave solid products of the type:

Physical and spectroscopic data (IR, Raman, and MS) are given and discussed.     

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:

     

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

.     

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.     

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.     

Synthesis,structures and magnetic properties of two iron(ii) tris(pyridyl)phosphine sulfide complexes

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Annelated tricyclic thiophenes and their photophysical properties

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Solvolysis of bridgehead chlorides with strained bridgehead double bond.

Product study and kinetic data of the solvolysis of the bridgehead chlorides (

) and (

indicate the neighboring group participation of the strained bridgehead double bonds.     

Sulfur nanoparticles stabilized in the presence of water-soluble polymers

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Penetration of methane–oxygen flames through flat obstacles with several openings

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Dimethylmalonoyl peroxide – the neglected lowest homologue: simple synthesis and high reactivity

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