Protecting allyloxycarbonyl

United States in 1979 Since nucleophiles are required to scavenge the allyl part of the protecting allyloxycarbonyl group, BujSn-H hydride donor and potassium alkanoates were used by Guibe and McCombie, respectively (Scheme 5). 

Allylamines are difficult to cleave with Pd catalysts. Therefore, amines are protected as carbamates, but not as allylamines. Also, allyl ethers used for the protection of alcohols cannot be cleaved smoothly, hence alcohols are protected as carbonates. In other words, amines and alcohols are protected by an allyloxycarbonyl (AOC or Alloc) group. 

H Kuntz, C Unverzagt. The allyloxycarbonyl (Aloe) moiety — conversion of an unsuitable into a valuable amino protecting group for peptide synthesis. Angew Chem Int Edn Engl 23, 436, 1984. 

O Dangles, F Guibe, G Balavoine, S Lavielle. A Marquet. Selective cleavage of the allyl and allyloxycarbonyl groups through palladium-catalyzed hydrostannolysis with tributyltin hydride. Application of the selective protection-deprotection of amino acid derivatives and in peptide synthesis. J Org Chem 52, 4984, 1987. 

T Vorherr, A Trzeciak, W Bannwart. Application of the allyloxycarbonyl protecting group for the indole of Trp in solid-phase peptide synthesis. Int J Pept Prot Res 48, 553, 1996. 

Synthesis of l,2-frans-2-Acetamido-2-deoxyglycosyl Amino Acids Using Carbamate (2,2,2-Trichloroethoxycarbonyl or Allyloxycarbonyl) Protection of the Amine... 

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... 

The syntheses of pyrimido[l,2-a]quinoline chromophore of pseudobactins are depicted in Schemes 6 and 7 (88MI4 90JOC4246). When allyloxycarbonyl and phthaloyl protective groups were used, then along with pyrimido[l,2-a]quinoline derivatives 410 and 411, tetracyclic 412, corresponding to the chromophore of azobactin, was formed (Scheme 6). Pyrimido[l,2- ]quinoline (413) was obtained in good yield when 2,2,2-... 

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). 

Scheme 23 Synthesis of Fmoc-Protected V -[2-(Allyloxycarbonyl)ethyl] Amino Acids by 1,4-Michael Addition to Amino Acid tert-Butyl EstersI1251...

Alcohols are protected as allyl ethers, which are difficult to cleave with the Pd catalyst and deprotected by other methods [149]. Alcohols are conveniently converted to allyl carbonates 334 by treatment with allyl chloroformate (333). The allyl carbonates are deprotected using HCO2H [150], and HSnBu3 [151]. This method is called the AOC (allyloxycarbonyl) method. Phenols are protected as allyl phenyl ethers, which can be cleaved with HSnBu3 [152]. 

Isoflavones result from the arylation of 3-(allyloxycarbonyl) chroman-4-ones with aryllead (IV) triacetates. Of particular interest is the introduction of a 2-hydroxy function through incorporation of a protected phenolic unit into the aryllead reagent (95JCS(P1)1679). 

Various other types of amine protection have been investigated as replacements for the native V-acetyl group in sialyl donors including Boc [54], allyloxycarbonyl [55], 9-fluorenylmethylcarbonyl [55], trichloroacetyl [55], and Cbz [55, 56] groups, but no particular advantages of these systems are apparent at present. 

The deblocking can be conducted in quantitavive yield, using trifluoroacetic acid at room temperature. Another protection group used in combination with EDC is the 3-(3-pyridyl)allyloxycarbonyl (Paloc) group. In this reaction DAEC is used in combination with N-hydroxybenzotriazole. 

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