Benzoic acid esters
Bz-OR, Benzoate ester, Benzoate
T. W. Green, P. G. M. Wuts,
Protective Groups in Organic Synthesis,
Wiley-Interscience, New York, 1999, 173-178, 712-715.
|H2O:||pH < 1, 100°C||pH = 1, RT||pH = 4, RT||pH = 9, RT||pH = 12, RT||pH > 12, 100°C|
|Reduction:||H2 / Ni||H2 / Rh||Zn / HCl||Na / NH3||LiAlH4||NaBH4|
|Oxidation:||KMnO4||OsO4||CrO3 / Py||RCOOOH||I2, Br2, Cl2||MnO2 / CH2Cl2|
4-(N,N-Dimethylamino)pyridine hydrochloride (DMAP·HCl) was used as a recyclable catalyst for the acylation of inert alcohols and phenols under base-free conditions. The catalyst can be reused more than eight times without loss in activity and works with various acylating reagents.
Z. Liu, Y. Liu, Q. Wang, Org. Lett., 2014, 16, 236-239.
Carbonylimidazole derivatives are highly active acylation reagents for esterification and amidation in the presence of pyridinium salts as catalysts. These reactions are thought to involve both Brønsted acid and nucleophilic catalysis. This mode of activation has been applied to the synthesis of difficult to access oxazolidinones, as well as esters and amides.
S. T. Heller, T. Fu, R. Sarpong, Org. Lett., 2012, 14, 1970-1973.
The use of diacyl disulfide as an acylation reagent enables an efficient ester formation under DMAP catalysis. A site-selective acylation of phenolic and primary aliphatic hydroxyl groups greatly expands the scope of protecting group chemistry. Diacyl disulfides offer excellent moisture tolerance, high efficiency, and potential in synthetic chemistry and biologically meaningful natural product modification.
H.-X. Liu, Y.-Q. Dang, Y.-F. Yuan, Z.-F. Xu, S.-X. Qiu, H.-B. Tan, Org. Lett., 2016, 18, 5584-5587.
Reversible covalent interactions of organoboron compounds enable a regioselective borinic acid-catalyzed acylation of polyols. This catalytic protocol enables differentiation of the secondary OH groups of a wide range of carbohydrate derivatives with diverse acid chloride and chloroformate reagents, using a structurally simple diarylborinic acid-derived catalyst.
D. Lee, M. S. Taylor, J. Am. Chem. Soc., 2011, 133, 3724-3727.
Highly regioselective monoprotection of hydroxyl groups in sugars was accomplished along with high chemical yield in the presence of dimethyltin dichloride as catalyst. The regioselectivity of the benzoylation of sugars is based on a stereorelationship among their hydroxyl groups.
Y. Demizu, Y. Kubo, H. Miyosho, T. Maki, Y. Matusumura, N. Moriyama, O. Onomura, Org. Lett., 2008, 10, 5075-5077.
Other Syntheses of benzoyl-protected Hydroxyl Groups
A very efficient and highly regioselective ring-opening reaction of epoxides with benzoic acid and its derivatives in the presence of cat. amount of tetrabutylammonium bromide (TBAB) in anhydrous acetonitrile gave selectively protected diols.
A. Khalafi-Nezhad, M. N. Soltani Rad, A. Khoshnood, Synthesis, 2003, 2552-2558.
An enantioselective Ni-catalyzed reaction of an alkyl halide (derived from an aldehyde and an acyl bromide), an olefin, and a hydrosilane provides esters of chiral dialkyl carbinols. The method is versatile and tolerates substituents that vary in size and that bear a range of functional groups. A four-component variant of this process, wherein the alkyl halide is generated in situ, is also reported.
Z.-P. Yang, G. C. Fu, J. Am. Chem. Soc., 2020, 142, 5870-5875.
Acyloxymethyl radicals, that add to imines, were generated from the corresponding iodomethyl esters by the action of dimethylzinc or triethylborane. A facile hydrolysis of the acyloxy moiety of the adducts gave the corresponding amino alcohols in good yield.
K.-i. Yamada, M. Nakano, M. Maekawa, T. Akindele, K. Tomioka, Org. Lett., 2008, 10, 3805-3808.
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.