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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, mechanistic organ ...
that forms a β-ketoester from the reaction of zinc
Zinc is a chemical element; it has symbol Zn and atomic number 30. It 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 periodic tabl ...
metal with an α-bromoester and a nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The name of the compound is composed of a base, which includes the carbon of the , suffixed with "nitrile", so for example is called " propionitrile" (or pr ...
. The reaction was first reported by Edmond Blaise (1872–1939) in 1901. The final intermediate is a metaloimine, which is then hydrolyzed to give the desired β-ketoester.
Bulky aliphatic esters tend to give higher yields. Steven Hannick and Yoshito Kishi 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 Mhydrochloric acid
Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is ...
hydrolyzes the β-enamino ester to turn the enamino into a ketone, forming the β-ketoester.
See also
* Blaise ketone synthesis * Reformatsky reactionReferences
# Edmond E. Blaise; ''Compt. Rend.'' 1901, ''132'', 478. # Rinehart, K. L., Jr. '' Organic Syntheses'', 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 (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...
'' 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.'' 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