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The Blaise reaction is an
Article
# Rao, H. S. P.; Rafi, S.; Padmavathy, K. ''
Blaise Reaction - Details and Recent Literature
{{Organic reactions Addition reactions Carbon-carbon bond forming reactions Name reactions
organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical ...
that forms a β-ketoester from the reaction of zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
metal with a α-bromoester and a nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix '' cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including me ...
. The reaction was first reported by Edmond Blaise (1872–1939) in 1901. The final intermediate is a metaloimine, which is then hydrolyzed
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolysis ...
to give the desired β-ketoester.
Bulky aliphatic
In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane ...
esters tend to give higher yields. Steven Hannick and Yoshito Kishi
is a Japanese chemist who is the Morris Loeb Professor of Chemistry at Harvard University. He is known for his contributions to the sciences of organic synthesis and total synthesis.
Kishi was born in Nagoya, Japan and attended Nagoya Univers ...
have developed an improved procedure.
It has been noted that free hydroxyl groups can be tolerated in the course of this reaction, which is surprising for reactions of organometallic halides.
Mechanism
The mechanism of the Blaise reaction involves the formation of an organozinc complex with the bromine alpha to the ester carbonyl. This makes the alpha carbon nucleophilic, allowing it to attack the electrophilic carbon of the nitrile. The negative nitrile nitrogen resulting from this attack complexes with the zinc monobromide cation. The β-enamino ester (tautomer of the imine intermediate pictured above) product is revealed by work-up with 50% K2CO3 aq. If the β-ketoester is the desired product, addition of 1 M hydrochloric acid hydrolyzes the β-enamino ester to turn the enamino into a ketone, forming the β-ketoester.
See also
* Blaise ketone synthesis *Reformatsky reaction
The Reformatsky reaction (sometimes misspelled Reformatskii reaction) is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters:
The organozinc reagent, also called a 'Reforma ...
References
# Edmond E. Blaise; ''Compt. Rend.'' 1901, ''132'', 478. # Rinehart, K. L., Jr. ''Organic Syntheses
''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and exp ...
'', Coll. Vol. 4, p. 120 (1963); Vol. 35, p. 15 (1955).Article
# Rao, H. S. P.; Rafi, S.; Padmavathy, K. ''
Tetrahedron
In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all ...
'' 2008, ''64'', 8037-8043. (Review)
# Cason, J.; Rinehart, K. L., Jr.; Thorston, S. D., Jr. '' J. Org. Chem.'' 1953, ''18'', 1594. ()
# Hannick, S. M.; Kishi, Y. '' J. Org. Chem.'' 1983, ''48'', 3833. ()
# Marko, I.E. ''J. Am. Chem. Soc.
The ''Journal of the American Chemical Society'' is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ''Journal of Analytical ...
'' 2007, ASAP
# Wang, D.; Yue, J.-M. '' Synlett'' 2005, 2077-2079.
External links
Blaise Reaction - Details and Recent Literature
{{Organic reactions Addition reactions Carbon-carbon bond forming reactions Name reactions