Nickel-catalyzed reaction of butadiene with strained ring olefins: Formation of a four-membered cyclic compound

Reaction of butadiene with strained ring olefins such as norbornene, dicyclopentadiene etc. Gives an exo-methylene- and methyl-substituted four-membered cyclic compound (II). The effective catalysts are (n-Bu₃P)₂NiBr₂/NaBH₄ or /alkoxide $\text{1}\text{1}$ syn-π-crotylbis(triethyl phosphite)nickel hexafluorophosphate (IV), and tetrakis(triethyl phosphite)nickel/CF₃COOH $\text{1}\text{1}$. π-Crotyl complex IV reacts with the strained ring olefins to give the corresponding product similarly. It is concluded that the active species for this catalytic reaction is a nickel hydride and that this reaction proceeds through π-crotyl intermediate.     

Activation of chlorobenzene as phenylating agent by means of a dinitrogen-molybdenum complex

Bis(dinitrogen)bis[1,2-bis(diphenylphosphino)ethane]molybdenum reacts with chlorobenzene to form molybdenum chloro complexes and phenylated organic products. Benzene, biphenyl, o-, m-, p-chlorobiphenyl, a dihydro derivative of o-chlorobiphenyl, triphenylphosphine and diphenylvinylphosphine were formed. The isomer distribution of the chlorobiphenyls is close to that obtained by decomposition of 0.02 M benzoyl peroxide in chlorobenzene under dinitrogen. The cleavage of the PhCl bond induced by the molybdenum-dinitrogen complex appears to give rise to the same homolytic reaction pattern. Phenylation of anisole and of triethyl phosphite has also been achieved with the same reagent.     

Wittig-horner reaction of a phosphonate of reissert analogue a new method for introduction of alkyl groups into isoquinoline

Dimethyl 2-isopropoxycarbonyl-1, 2-dihydroisoquinoline-1-phosphonate ($\text{1}$) was prepared from isoquinoline, isopropyl chloroformate, and trimethyl phosphite. Wittig-Horner reaction of $\text{1}$ with various aldehydes afforded the corresponding exo-methylene compounds, which were converted to 1-substituted isoquinolines with hydrogen chloride.     

The effect of ortho substituents in SRNl reactions. Some synthetic applications

Several $\text{ortho}$-substituted iodobenzenes were allowed to react, via the S_RNl mechanism, with mixtures of diethyl phosphite ion and pinacolone enolate ion. From product composition data, the relative reactivities of the two nucleophiles were reckoned. They represent relative reactivities in attachment to aryl radical intermediates. Most of the $\text{ortho}$ effects are slight, but there is evidence that large $\text{ortho}$ substituents hinder attachment of the phosphite more than the enolate nucleophile. The methoxy and diethoxyphosphoryl substituents, when $\text{para}$ to the site of substitution, respectively favour and disfavour the phosphite with respect to the enolate ion. S_RNl reactions of $\text{ortho}$-substituted halobenzenes are, for some substituents, followed by other reactions which afford products of synthetic interest.     

Nouveaux trioxophosphetanes generateurs d'oxygene singulet a basse temperature

We have prepared phosphite ozonides $\text{1b}$–$\text{3b}$ which are efficient and clean singlet oxygene generators at low temperature.     

The reactions of a secondary phosphite with chloro- and pentan-2,4-dionato complexes of iridium(I) and rhodium(I)

The secondary phosphite $\text{OCH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{OP}$(O)H reacts with chlorobis(cyclooctene) rhodium(I) dimer to give RhX(R₂POHOPR₂)₂(R₂POH) (X=H, Cl) and RhCl₂(R₂POHOPR₂)(R₂POH)₂ where R₂PO = $\text{OCH}{}_2\text{CMe}{}_2\text{CH}{}_2\text{P}$O. The iridium analogue yields corresponding products. The phosphite reacts with bis-(cyclooctene) pentan-2,4-dionatorhodium(I)to give Rh(R₂POHOPR₂)₃ and with the corresponding iridium complex to produce Ir(acac)(R₂POHOPR₂)₂. Some of the complexes act as catalysts or catalytic precursors for the stereoselective reduction of 4-t-butylcyclohexanone.     

Syntheses of bis(imino)thietans

The reactions of sulfonyliminothiirans ($\text{1}$) with isonitriles and those of ketenimines with arylsulfonyl isothiocyanates yield the title compounds $\text{2}$. In contrast, benzoyl isothiocyanate undergoes a Diels-Alder reaction with ketenimines to give 1,3,5-oxadiazine-4-thiones ($\text{3}$).     

N-halogeno-compounds. Part 9 [1]. Azoxy- and azo-arenes derived from 4-(dichloroamino)tetrafluoropyridine; crystal structure of trans-2,3,5,6-tetrafluoro-4-(2,4,6-trimethylphenyl-onn-azoxy)pyridine

The nitrosoarenes ArNO (Ar = C₆H₅, 2-MeC₆H₄, 2,4,6- Me₃C₆H₂ and C₆F₅) have been condensed with 4-(dichloroamino)- tetrafluoropyridine to provide the azoxy-compounds py_FN$\text{N}\text{+}$($\text{N}\text{-}$)Ar (py_F = 2,3,5,6-tetrafluoro-4-pyridyl); de-oxygenation of the first three with triphenylphosphine or triethyl phosphite gave the corresponding azo-compounds, and the reverse reaction was achieved in the case of py_FNNC₆H₂Me₃-2,4,6 using peroxytrifluoroacetic acid. Thermolysis of 4-azidotetrafluoropyridine in the presence of pentafluoronitrosobenzene provided the perfluorinated azoxy-compound py_FN$\text{N}\text{+}$($\text{O}\text{-}$)C₆F₅. X-Ray methods have been used to determine the molecular geometry of py_FN$\text{N}\text{+}$($\text{O}\text{-}$)C₆H₂Me₃-2,4,6.     

Conversion of 3-Azido-5-phenyl-1,2,4-oxadiazole into benzoyl cyanide; a new thermal fragmentation

Flash vacuum pyrolysis of 3-azido-5-phenyl-1,2,4-oxadiazole ($\text{1a}$) gives benzoyl cyanide for which a mechanism involving the formation and fragmentation of $\text{N}$-benzoylpentaazafulvene ($\text{3}$) is proposed.     

Reaction of gem-nitronitroso-compounds with triethyl phosphite

2-Nitro-2-nitrosopropane reacts with triethyl phosphite by deoxygenation of the nitroso- group to give 2-nitriminopropane; 1-nitro-1-nitrosocyclohexane reacts similarly. The reaction proceedsvia an intermediate detectable byNMR; possible structures for this intermediate and for the course of the reaction are discussed. Some reactions of nitrimines are also reported.     

The benzoylation of uracil and thymine

Uracil and thymine react with benzoyl chloride in acetonitrile-pyridine solution at room temperature to give first their 1-$\text{N}$-benzoyl (2b and 3b) and then their 1-$\text{N}$, 3-$\text{N}$-dibenzoyl derivatives (4a and 4b, respectively); the latter compounds are converted into the corresponding 3-$\text{N}$-benzoyl derivatives (5a and 6a) under mild conditions of basic hydrolysis.     

Synthesis of 2-phosphonopyrrolidine and its substitution for proline in an inhibitor of angiotensin-converting enzyme

The title compound was synthesized $\text{via}$ its diethyl ester from 1-pyrroline trimer and diethyl phosphite. The 3-mercaptopropanoyl derivative inhibited angiotensin converting enzyme with I₅₀ = 1.7 μM.     

Synthesis and characterization of 4-dimethylamino-N-triphenylmethylpyridinium chloride,a postulated intermediate in the tritylation of alcohols

4-Dimethylamino-$\text{N}$-triphenylmethylpyridinium chloride ($\text{1}$) reacts with primary but not secondary alcohols to produce trityl ethers in good yield; in addition, amines may be selectively $\text{N}$- tritylated witth $\text{1}$ in the presence of alcohols.     

Some syntheses using tetrakis(trifluoromethyl)dewar thiophene

Tetrakis(trifluoromethyl)Dewar thiophene ($\text{1}$) is found to be a good dipolarophile and dienophile. Therefore, $\text{1}$ reacts with any kind of azides to give 1,3-dipolar cycloadducts, which are transformed to tetrakis(trifluoromethyl)Dewar pyrroles ($\text{2}$), compounds of a new cyclic ring system. Further, $\text{1}$ reacts with cyclic or acyclic dienes to give Diels-Alder adducts. The adduct ($\text{3}$) of $\text{1}$ with butadiene was transformed to tetrakis(trifluoromethyl)cyclooctatetraene ($\text{4}$) by desulfurization, bromination and dehydrobromination, stepwise. Valence-bond isomerisation of $\text{4}$ will be presented.

     

1,4-diacetoxy-β-lactams. Reactions with nucleophiles

β-Lactam $\text{1}$ reacts with hetero nucleophiles under ring cleavage to give 2,2-dimethyl-3-oximinobutanoic esters $\text{6}$ and $\text{7}$. $\text{N}$-hydroxyazetidine $\text{5}$, the precursor of β-lactam 1, is prepared by a new method.     

Synthesis of silylated methylenecyclopropanes

2-Trimethylsilylmethylenecyclopropane (=3) was synthesized by reaction of lithio methylenecyclopropane with TMSCl. The lithium salt of (=3) reacts with some electrophiles by α- or γ-attack depending on the nature of the electrophile. Whereas alkenylbromides $\text{8}$ and $\text{9}$ or alkinylbromide $\text{10}$ give exclusively α-attack, benzaldehyde reacts with γ-alkylation.     

Difluoromethylene exchange in the preparation of fluorinated bis-phosphonates

The application of the Michaelis-Becker variation to the preparation of unsymmetrical $\text{F}$-methylene $\text{bis}$-phosphonates gives a mixture of both symmetrical and unsymmetrical $\text{bis}$-phosphonates. The reaction is best explained by dissociation of the intermediate $\text{F}$-methylene phosphonate ylide and carbene scrambling among the potential dialkyl phosphite anions.     

Triplet-mediated coupling of 5-bromo-1,3-dimetrhyluracil to Nb-methoxycarbonyltryptamine involving a double electron transfer

On acetone-sensitization, 5-bromo-1,3-dimethyluracil ($\text{1}$ reacts with N^b-methoxycarbonyltryptamine ($\text{4}$ under the assistance of an electron carrier such as 2-methoxynaphthalene to give a coupling product $\text{6}$. A mechanism involving a double electron transfer via the triplet state of $\text{1}$ is proposed.     

A stereocontrolled synthesis of Z and E terminal dienes from pinacol E-1-trimethylsilyl-1-propene-3-boronate

Pinacol $\text{E}$-1-trimethylsilyl-1-propene-3-boronate reacts with aldehydes to form (±)-($\text{R}$*,$\text{S}$*)-3-trimethylsilyl-4-hydroxy-1-alkenes, which can be deoxysilylated stereoselectively to either 98% $\text{Z}$ or 99% $\text{E}$ 1,3-dienes, including the separate components of the red bollworm moth pheromone.     

1-phenyl-3-(trifluormethansulfonyl)-propadien

For the first time a perfluoroalkanesulfonylallene, the 1-phenyl-3-(trifluoromethanesulfonyl)-propadiene ($\text{5}$) was synthesized. $\text{5}$ is $\text{5}$ reacts already at room temperature with cyclopentadiene to form the adduct $\text{6}$.