Categories: O-H Bond Formation >
Cleavage of esters
N,N-diarylammonium pyrosulfate efficiently catalyzes the hydrolysis of esters under organic solvent-free conditions. This reverse micelle-type method is successfully applied to the hydrolysis of various esters without the decomposition of base-sensitive moieties and without any loss of optical purity for α-heterosubstituted carboxylic acids.
Y. Koshikari, A. Sakakura, K. Ishihara, Org. Lett., 2012, 14, 3194-3197.
Acetyl-, benzoyl- and pivoyl-protected alcohols and phenols undergo smooth deacylation in a two-phase system of powdered NaOH and Bu4NHSO4 in THF or CH2Cl2.
R. D. Crouch, J. S. Burger, K. A. Zietek, A. B. Cadwallader, J. E. Bedison, M. M. Smielewska, Synlett, 2003, 991-992.
The reaction of different esters, thioesters and amides derived from pivalic, benzoic and 4-tert-butylbenzoic acids with an excess of lithium and a catalytic amount of naphthalene led, after methanolysis, to the corresponding alcohols, thiols and amines, respectively, through a reductive non-hydrolytic procedure.
C. Behloul, D. Guijarro, M. Yus, Synthesis, 2006, 309-314.
In a general method for the preparation of α-hydroxyacetophenones, functionalized arylmagnesium species are transmetalated to the corresponding arylzinc intermediates, which undergo Cu(I)-catalyzed reaction with acetoxyacetyl chloride. Acidic hydrolysis of the acetate group releases the target α-hydroxyacetophenones with minimal production of undesired polymeric side products.
M. McLaughlin, J. M. Belyk, G. Qian, R. A .Reamer, C.-y. Chen, J. Org. Chem., 2012, 77, 5144-5148.
Deprotection of allyl ethers, amines and esters to liberate hydroxyl, amino and acid groups is achieved under mild conditions. The reagent combination employed for this transformation is polymethylhydrosiloxane (PMHS), ZnCl2 and Pd(PPh3)4.
S. Chandrasekhar, R. Reddy, R. J. Rao, Tetrahedron, 2001, 57, 3435-3438.
The homoallyl moiety (hAllyl) can be used as a general protecting group for several functionalities. It can be chemoselectively removed via a sequential, one-pot cross-metathesis/elimination sequence.
B. H. Lipshutz, S. Ghorai, W. W. Y. Leong, J. Org. Chem., 2009, 74, 2854-2857.