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A novel catalytic route for the direct synthesis of bis-oxazolidino-nedienes from CO2 and propargylic amines is presented. An inexpensive copper catalyst promotes the Glaser coupling and a subsequent double cyclization step. The obtained diene derivatives undergo polymerization in the solid state, showcasing a rare example of spontaneous topochemical polymerization. [ABSTRACT FROM AUTHOR]

Propargyl ureas can lead to a range of possible heterocyclic compounds, mainly depending on the employed catalyst. Silver salts are known to promote the N-5-exo-dig cyclization mode to imidazolidinone derivatives. Conversely, a versatile and stereoselective O-5-exo-dig cyclization of propargyl ureas to 2-aminooxazolines by Ag(I) catalysis is here disclosed. Good to excellent yields and complete stereoselectivity of the external double bond have been achieved under milder reaction conditions (50-60 °C). A one-pot protocol starting from the corresponding propargylic amines and isocyanates has been developed as well. N,N'-Dipropargyl ureas underwent a uncommon O-5-exo-dig/N-5-endo-dig double cyclization sequence. Finally, insights into the tautomeric equilibrium of 2-aminooxazoles and on their relative reactivity are provided. [ABSTRACT FROM AUTHOR]

Despite the advances in the field of carbon‐halogen bond formation, the straightforward catalytic access to selectively functionalized iodoaryls remains a challenge. Here, we report a one‐pot synthesis of ortho‐iodobiaryls from aryl iodides and bromides by palladium/norbornene catalysis. This new example of Catellani reaction features the initial cleavage of a C(sp2)−I bond, followed by the key formation of a palladacycle through ortho C−H activation, the oxidative addition of an aryl bromide and the ultimate restoration of the C(sp2)−I bond. A large variety of valuable o‐iodobiaryls has been synthesized in satisfactory to good yields and their derivatization have been described too. Beyond the synthetic utility of this transformation, a DFT study provides insights on the mechanism of the key reductive elimination step, which is driven by an original transmetallation between palladium(II)‐halides complexes. [ABSTRACT FROM AUTHOR]

In the presence of Pd[(OAc).sub.2] and norbornene as catalysts, two molecules of an ortho-substituted aryl iodide undergo aryl-aryl coupling to a palladium-bonded biphenylyl intermediate, which is hydrogenolyzed by benzyl alcohol to give 2,3'-disubstituted biaryl derivatives in satisfactory yields. A curious behaviour was observed with o-chloroiodobenzene, which gave activation of the C--Cl bond with four-membered ring formation. Key words: biphenyls, aryl-aryl coupling, multistep reactions, palladium, palladacycles, C-H activation, catalysis. En presence de Pd[(OAc).sub.2] et de norbornene agissant comme catalyseurs, deux molecules d'iodure d'aryle substituees en ortho subissent une reaction de couplage aryle-aryle conduisant a un intermediaire biphenylyle lie au palladium qui peut subir une reaction d'hydrogenolyse sous l'action de l'alcool benzylique pour conduire a la formation de derives biaryles 2,3'-disubstitues, avec des rendements satisfaisants. On a observe un comportement bizarre avec l'o-chloroiodobenzene donne lieu a une activation de la liaison C--Cl avec formation d'un cycle a quatre membres. Mots cles : biphenyles, couplage aryle-aryle, reactions en plusieurs etapes, palladium, palladacyles, activation C-H, catalyse. [Traduit par la Redaction]

Research has been conducted on the dichloro-bridged arylbicycloheptylpalladium complexes. The synthesis and characterization of these complexes have been carried out and the dimers bearing methyl groups at different para, meta and ortho aromatic positions have been investigated and discussed.

Palladium catalyzed sequential coupling of an aryl iodine bearing an ortho electron-donating group with an aryl bromide is reported selectively forms biphenyls compound with two different substituents, R1 and R2. Unsymmetrical aryl coupling is obtained selectively on the basis different reactivity of certain bromo and iododerivatives with palladium(0) and palladium(II) complexes.

Dihydrodibenzo[b,f]azepines and dibenzo[b,f]azepines can be efficiently synthesized from aryl bromides, o‐bromoanilines and norbornene or norbornadiene by means of palladium catalysis. This protocol gives access to dibenzo[b,f]azepine core containing a variety of electron‐withdrawing substituents on both aromatic rings and complements the previously reported methodology where electron rich aryl iodides were preferentially used. The presence of KI, even in sub‐stoichiometric amount, is crucial for this three‐component reaction. The proper addition of iodide anions has a dramatic effect on reaction rate and selectivity. A formal three‐step synthesis of the tricyclic antidepressant Clomipramine (Anafranil®) is also described. KI‐ck‐start required: Dibenzo[b,f]azepine derivatives can be efficiently synthesized from aryl bromides, o‐bromoanilines and norbornene or norbornadiene by means of palladium catalysis. The presence of KI, even in sub‐stoichiometric amount, is crucial for this three‐component reaction, as it promotes reaction rate and selectivity. A formal three‐step synthesis of the tricyclic antidepressant Clomipramine (Anafranil®) is also described. [ABSTRACT FROM AUTHOR]

A catalytic procedure involving palladacycles is described, which is applied to the synthesis of condensed quinolin-4(5H)-ones starting from o-substituted iodoarenes and amides of o-bromo arene- and heteroarenecarboxylic acids. It is believed that this work opens up the access to important classes of compounds through one-pot procedures much simpler than the conventional ones.