Carboxylic allyl esters

Deprotection of allyl groups from carboxylic allyl esters is also possible using these conditions [31, 33]. In a homogeneous CH3CN/H20 medium, the facility of cleavage of the allyl group follows the order allyl > cinnamyl > dimethylallyl. 

Wilson T, Zhang J, Oloman C, Wayner D. Anthraquinone-2-carboxylic-allyl ester as a new electrocatalyst for dioxygen reduction to produce H2O2. Int J Electrochem Sci 2006 1 99-109. 

Hydrogenolysis of the diallyl alkylmalonate 757 with formic acid in boiling dioxane affords the monocarboxylic acid 758. Allyl ethyl malonates are converted into ethyl carboxylates[471]. The malonic allyl ester TV-allylimide 759 undergoes smooth deallylation in refluxing dioxane to give the simple imide 760(472]. The allyl cyanoacetate 761 undergoes smooth decarboxylation to give... 

Cooper(I) carboxylates give esters with primary (including neopentyl without rearrangement), secondary, and tertiary alkyl, allylic, and vinylic halides. A simple Sn mechanism is obviously precluded in this case. Vinylic halides can be converted to vinylic acetates by treatment with sodium acetate if palladium(II) chloride is present. ... 

Silyl-derived linker 36 was prepared in three steps from a silyl ether of serine and incorporated for Fmoc/tBu-based assembly of protected gly-copeptide blocks (Scheme 11) [42]. The a-carboxylic acid function of serine was protected as an allyl ester. Deprotection by a Pd(0) catalyst in the presence of dimedone liberated the carboxylic acid in order for subsequent... 

Wong and co-workers have prepared various quaternary cx-nitro-cx-methyl carboxylic acid esters by the palladium-catalyzed allylic alkylation of a-nitropropionate ester (Eq. 5.59). The products can be kinetically resolved by using cx-chymotrypsin and are converted into optical active a-methyl cx-amino acids. Such amino acids are important due to the unique biological activity of these nonproteinogenic a-amino acids.82... 

Hydrolysis of allyl ester 201b was performed with diethylamine in the presence of Pd(PPh3)4. The carboxylic acid 201c thus obtained could be amidated with a tryptophan derivative using l-(3-dimethylaminopropyl)-3-ethylcarbodiimide as... 

Synthesis of isomeric chiral protected (63 )-6-amino-hexahydro-2,7-dioxopyrazolo[l,2- ]pyrazole-l-carboxylic acid 280 is shown in Scheme 36. Crude vinyl phosphonate 275, obtained by treatment of diethyl allyloxycarbonylmethyl-phosphonate with acetic anhydride and tetramethyl diaminomethane as a formaldehyde equivalent, was used in the Michael addition to chiral 4-(f-butoxycarbonylamino)pyrazolidin-3-one 272. The Michael addition is run in dichloro-methane followed by addition of f-butyl oxalyl chloride and 2 equiv of Huning s base in the same pot to provide 276 in 58% yield. The allyl ester is deprotected using palladium catalysis to give the corresponding acid 277, which is... 

Carboxylic acids are regenerated from their corresponding substituted allyl esters on montmorillonite K10 using microwave irradiation under solvent-free conditions to afford enhanced yields and reduced reaction times when compared to thermal conditions [108] (Eq. 58). 

The reaction of tert-butyl esters with Et3SiH/TFA results in the reductive deprotection of the ester and formation of isobutane. The yields of the isobutane are not recorded, but the acids are obtained nearly quantitatively (Eq. 150).307 In a similar manner, the lactone shown in Eq. 151 is converted into the acid in good yield.308 In like manner, the reductive deprotection of allyl esters provides the carboxylic acids in high yields.270... 

Rearrangement of allyl trimethylsilyl ketene acetal, prepared by reaction of allylic ester enolates with trimethylsilyl chloride, to yield Y,5-unsaturated carboxylic a-cids. The Ireland-Claisen rearrangement seems to be advantageous to the other variants of the Claisen rearrangement in terms of E/Z geometry control and mild conditions. 

Another method for deallylation of allyl esters is the transfer of the allyl group to reactive nucleophiles. Amines such as morpholine are used[415-417], Potassium salts of higher carboxylic acids are used as an accepter of the allyl group[418]. The method is applied to the protection and deprotection of the acid function in rather unstable /3-lactam 664[419,420]. 

Enolate formation with an allyl ester can give 2-substituted carboxylic acids. 

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