Alkoxy- and hydroxycyclization of enynes catalyzed by Pd(II) and Pt(II) catalysts

The development of a novel reaction ideal in terms of atom economy was achieved. The scope of the reaction was evaluated in the presence of Pd and Pt catalysts. The first enantioselective Pt-promoted enyne carboalkoxycyclization was developed in up to 85 % stereoselectivity. This ideal atom-economical reaction afforded the corresponding functionalized five-membered carbo- and heterocycles in good to excellent yields. The use of silver salts combined with (R)-Ph-BINEPINE, a monophosphane atropisomeric ligand, was found to be the best-suited combination for moderate to high enantioselectivities on carbonated and nitrogenated substrates

Synthesis of (3S, 4S)-4-hydroxy-2, 3, 4, 5-tetrahydropyridazine-3-carboxylic acid, component of luzopeptin A.

International audienceThe enantioselective synthesis of (3S, 4S)-4-hydroxy-2, 3, 4, 5-tetrahydropyridazine-3-carboxylic acid 1 is described. The two stereogenic centers in anti relationship are obtained by sequential enantio and chemoselective hydrogenation of β-ketoester in presence of chiral ruthenium catalyst and diastereoselective amination of β-hydroxyester with di t-butylazodicarboxylate

Selective deprotection of allyl amines using palladium

Mono and diallylamines can be cleaved using Pd(0) catalyst and 2-mercaptobenzoic acid as nucleophile. This methodology has been successfully used for the sequential deprotection of diallylamines. The yields of desallylation are good to quantitative

A new strategy for the synthesis of selectively protected spermidine and norspermidine derivatives

The synthesis of spermidine derivatives holding three independently removable N-protecting groups has been achieved from diallylamine using the key sequence : selective palladium-catalyzed monodesallylation of diallylamines / N-alkylation

Intramolecular Heck-type Reactions in Aqueous Medium. A Dramatic Change in Regioselectivity

Efficient intramolecular Heck-type cyclizations were carried out in aqueous medium using water-soluble Pd/TPPTS catalysts. Under these conditions, the generally observed exo process was reversed in favor of the regioselective formation of endo cyclized compounds

C 1 -Symmetric Monosubstituted Chiral Diene Ligands in Asymmetric Rhodium-Catalyzed 1,4-Addition Reactions

One trumps two: Monosubstituted chiral bicyclo[2.2.2]octadiene ligands, derived from carvone, form complexes with rhodium to catalyze the asymmetric addition of boronic acid substrates to α,β-unsaturated ketones. The 1,4-adducts are produced in good yield and high enantioselectivity

Chemoselective Removal of Allylic Protecting Groups Using Water-Soluble Pd(OAc)2/TPPTS Catalyst

The removal of allylic protecting groups promoted by the catalytic system Pd(OAc)(2)/TPPTS has been achieved on bifunctional substrates with complete chemoselectivity and high efficiency, in aqueous media. By lowering the amount of palladium catalyst, substituted allylic carboxylates remained unaffected while allylcarbamates, in the same molecule, were quantitatively removed. When using a biphasic C3H7CN-H2O solvent, the water-soluble catalyst could also differentiate allylcarbonates from dimethylallylcarbamates on diprotected amino alcohols. All these reactions were carried out under mild and neutral conditions which are compatible with a large range of molecules including beta-lactams