Jean-Marie Bernard

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.

SELECTIVE DEPROTECTIVE METHOD USING PALLADIUM-WATER SOLUBLE CATALYSTS

Allylcarboxy and Allyloxycarbonyl groups can be removed without affecting dimethylallylcarboxy and cinnamylcarboxy groups in the same molecule. using Pd(0) water soluble catalyst prepared in situ, with diethylamine as allyl scavenger. Homogeneous or biphasic media are suitable: the yields of deprotection are quantitative.

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.

Synthesis of peptides using palladium promoted selective removal of allyloxycarbonyl protecting groups in aqueous medium

Peptides can be easily synthesized according to a stepwise strategy in solution without any purification. The selective removal of allyloxycarbonyl protecting groups catalyzed by a water-soluble palladium catalyst constitutes the key step of the peptide chain elongation

Peptide synthesis by sappho technology

Publisher Summary This chapter illustrates that the SAPPHO process is a new and powerful method of synthesizing peptides, at a low cost, with very good yield and purity. It is the first automated peptide synthesis technology that can be used to synthesize peptide or peptide fragments from 3–15 aminoacids. Peptides are molecules very active at low concentration. They are used in pharmaceutical, agrochemical, and nutritional areas. The synthesis of these compounds is very dependant on the sequence and the quantity required. To synthesize short peptides, at high volume and low cost, chemists prefer to use the N carboxyanhydrides (NCA) of aminoacids, protected if necessary on the side chain reactive functional groups.

A New and Practical Removal of Allyl and Allyloxycarbonyl Groups Promoted by Water-Soluble Pd(0) Catalysts

Publisher Summary This chapter illustrates a smooth and efficient methodology for the cleavage of allyloxycarbonates, allylcarbamates and allyl carboxylates using Pd(OAc) 2 / TPPTS catalyst in aqueous medium. The free parent molecules are easily isolated from the reaction mixture by simple aqueous work-up and extraction; they are generally pure enough to be used in another step without any further purification. Moreover, the use of a two-phase system affords a valuable solution for the deprotection of secondary amines which are obtained without any N-allylated side product. In addition, in a biphasic medium the recycling of the active catalyst is particularly attractive from an industrial view point. Finally, chemo selective deprotection of bifunctional molecules containing differently substituted allylic groups was performed with high efficiency. Various applications of this technique are under investigation in our laboratory, especially in the field of peptide synthesis.