Allyloxycarbonyl, removal

PdCl2(Ph3P)2, dimedone, THF, 95% yield. This method is also effective for removing the allyloxycarbonyl group from alcohols and amines. 

Selective removal of allyl and allyloxycarbonyl protecting groups promoted by Pd/tppts catalytic systems (Equation 14) 43 536 540 Hydrocyanation of 1,3-butadiene and 3-pentene nitrile to adiponitrile (Equation 15) catalysed by Ni/tppts systems in the presence of reducing agents, such as NaBfL, or ZnCb49 541-542... 

F.Guibf and Y. Saint M Leux, The allyloxycarbonyl group for alcohol protection Quantitative removal or transformation into allyl protecting group via w-allyl complexes of palladium, Tetrahedron Lett. 22 3391 (1981). 

As has already been detailed for the allyloxycarbonyl (Aloe) moiety, allyl esters also proved to be very versatile and useful carboxy-protecting groups. They can be easily constructed by azeotropic esterification or nucleophilic displacement on allylic halides. For the cleavage of these esters lithium di-methylcuprate can be used. However, a much milder method is found in the Rh -catalyzed isomerization of the allyl moiety to a propenyl ester which immediately hydrolyzes under the reaction conditions (Scheme 67). Even milder is the Pd°-catalyzed allyl transfer to morpholine as an accepting nucleophile. The removal of allyl ester protection has earlier been used in particular in -lactam anti-... 

A fourth urethane protecting group, the TV-allyloxycarbonyl group (Alloc) is introduced in the usual way using allyl chloroformate or diallyl dicarbonate. Its main interest concerns its removal by a Pd-catalysed hydrostannolysis with tri-butyltin hydride (Scheme 7.4). It thus provides orthogonal protection without the need to expose the peptide to acid, conditions that would cleave, for example, O-gly-coside derivatives of peptides. 

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