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Synthesis of thioesters and thioacids
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Recent Literature
An efficient, fast and convenient protocol for the synthesis of N-urethane-protected
α-amino/peptide thioacids from their corresponding acids and Na2S is
mediated by EDC. The chemistry is compatible with a wide variety of urethane
protecting groups, side-chain functionalities, and sterically hindered amino
acids.
T. M. Vishwanatha, M. Samarasimhareddy, V. V. Sureshbabu, Synlett, 2012, 23,
89-92.
A thiazolium precatalyst facilitates electrochemical oxidation of thiolate
anions, leading to deleterious formation of disulfide byproducts. For the
reaction of a broad range of aldehyde and thiol substrates, thioesters were
obtained in very good yields . This approach provides an atom-efficient
thioesterification that circumvents the need for stoichiometric exogenous
oxidants, high cell potentials, or redox mediators.
K. A. Ogawa, A. J. Boydston, Org. Lett., 2014,
16, 1928-1931.
4,4′-azopyridine is a suitable electron-deficient reagent for Mitsunobu
esterification and thioesterification reactions. This new reagent facilitates
the isolation of its hydrazine byproduct without restricting the reaction scope.
The pyridine hydrazine byproduct can be simply reoxidized. The stereochemistry
of the reaction under the reported conditions is with perfect retention of
configuration.
N. Iranpoor, H. Firouzabadi, D. Khalili, S. Motevalli, J. Org. Chem., 2008,
73, 4882-4887.
Reduction of ethanethiol esters of α-amino acids to α-amino aldehydes by
triethylsilane and catalytic palladium-on-carbon is described. α-Amino aldehydes
with Boc, Cbz, or Fmoc protection could be obtained without racemization in high
yield.
H. Tokuyama, S. Yokoshima, S.-C. Lin, L. Li, T. Fukuyama, Synthesis, 2002, 1121-1123.
Diverse thiol esters were synthesized in good yields by reactions of thiophenol,
benzyl mercaptan, ethyl mercaptoacetate, and mercaptoacetic acid with N-acylbenzotriazoles
under mild conditions. These results demonstrate the utility of N-acylbenzotriazoles
as mild S-acylating agents.
A. R. Katritzky, A. A. Shestopalov, K. Suzuki, Synthesis,
2004,
1806-1813.
The addition of 3-10 mol-% DMAP accelerates the
DCC-activated esterification of carboxylic acids with alcohols and thiols to
such an extent that formation of side products is suppressed and even sterically
demanding esters are formed in good yields at room temperature.
B. Neises, W. Steglich, Angew. Chem. Int. Ed., 1978,
17, 522-524.
A convenient procedure allows the synthesis of esters and thioesters from the
corresponding carboxylic acid using TFFH as the coupling reagent. The
preparation of N-acyl-dithiocarbamates from carboxylic acids and
1,3-thiazolidine-2-thione is also described.
M. Pittelkow, F. S. Kamounah, U. Boas, B. Pedersen, J. B. Christensen, Synthesis,
2004, 2485-2492.
The facile and efficient conversion of a tert-butyl protecting group
to an acetyl protecting group by catalytic amounts of bromine in acetyl
chloride and the presence of acetic acid has been developed. The fairly mild reaction conditions are of particular interest for
new protecting group strategies for sulfur functionalised target structures.
A. Blaszczyk, M. Elbing, M. Mayor, Org. Biomol. Chem., 2004, 2,
2722-2724.
Various alcohols, thiols, phenols, and amines can be acetylated using acetic
anhydride in the presence of catalytic quantity of silver triflate. The method
proceeds under mild conditions, does not involve cumbersome workup, and the
resulting products are obtained in high yields within a reasonable time.
R. Das, D. Chakraborty, Synthesis, 2011,
1621-1625.
Various alcohols, phenols, amines and thiols
may easily be converted into acetate derivatives by treatment
with acetic anhydride in the presence of
acetonyltriphenylphosphonium bromide in good yields at room
temperature. With the same precatalyst, both aliphatic and aromatic aldehydes
can be transformed into the corresponding gem-diacetates under reflux
conditions.
A. T. Khan, L. H. Choudry, S. Ghosh, Eur. J. Org. Chem., 2005,
2782-2787.
Copper(II) tetrafluoroborate efficiently catalyzes acetylation of
structurally diverse phenols, alcohols, thiols, and amines with
stoichiometric amounts of Ac2O under solvent-free conditions at
room temperature. Acid-sensitive alcohols are smoothly acetylated without
competitive side reactions.
A. K. Chakraborti, R. Gulhane, Shivani, Synthesis, 2004,
111-115.
An atom efficient esterification could be
achieved using hafnium(IV) or zirconium(IV) salts.
K. Ishihara, M. Nakayama, S. Ohara, H. Yamamoto, Tetrahedron,
2002, 58, 8179-8188.
Acylation of alcohols, thiols, and sugars were studied with a variety of
Lewis acids, and it was found that Cu(OTf)2 was very efficient in
catalyzing the reaction under mild conditions in CH2Cl2.
K. L. Chandra, P. Saravan, R. K. Singh, V. K. Singh, Tetrahedron, 2002, 58,
1369-1374.
The combination of thiols as nucleophiles and a bidentate ligand enable a
palladium-catalyzed thiocarbonylation of styrene derivatives with high
regioselectivity toward the more valuable branched isomer. The ambient reaction
conditions (temperature, catalyst loading) and the use of a CO surrogate render
this transformation a useful method for the synthesis of thioesters.
V. Hirschbeck, P. H. Gehrtz, I. Fleischer, J. Am. Chem. Soc., 2016,
138, 16794-16799.
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