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Ethyl diazoacetate (N=N=CHC(O)OC 2 H 5) is a diazo compound and a reagent in organic chemistry. It was discovered by Theodor Curtius in 1883. [4] The compound can be prepared by reaction of the ethyl ester of glycine with sodium nitrite and sodium acetate in water. As a carbene precursor, it is used in the cyclopropanation of alkenes.
The Buchner ring expansion is a two-step organic C-C bond forming reaction used to access 7-membered rings. The first step involves formation of a carbene from ethyl diazoacetate, which cyclopropanates an aromatic ring. The ring expansion occurs in the second step, with an electrocyclic reaction opening the cyclopropane ring to form the 7 ...
In organic chemistry, the Roskamp reaction is a name reaction describing the reaction between α-diazoesters (such as ethyl diazoacetate) and aldehydes to form β-ketoesters, often utilizing various Lewis acids (such as BF 3, SnCl 2, and GeCl 2) as catalysts. [1] [2] [3] The reaction is notable for its mild reaction conditions and selectivity.
The Buchner–Curtius–Schlotterbeck reaction is the reaction of aldehydes or ketones with aliphatic diazoalkanes to form homologated ketones. [1] It was first described by Eduard Buchner and Theodor Curtius in 1885 [ 2 ] and later by Fritz Schlotterbeck in 1907. [ 3 ]
This reaction is also called the Regitz diazo transfer. [7] Examples are the synthesis of tert-butyl diazoacetate [8] and diazomalonate. [9] Methyl phenyldiazoacetate is generated in this way by treating methyl phenylacetate with p-acetamidobenzenesulfonyl azide in the presence of base. [10] [11]
The periselectivity of a particular reaction depends on the structure of both the ketene and the substrate. Although the reaction is predominantly used to form four-membered rings, a limited number of substrates undergo [3+2] or [4+2] reactions with ketenes. Examples of all three modes of cycloaddition are discussed in this section.
For the second generation reaction starting with the diazoketone, the reaction is performed by irradiation of a 0.7 M solution of the ketone with 1.0-1.2 equivalents of acetylene. A low-pressure mercury-vapor lamp at 254 nm in a photochemical reactor is used for 5–8 hours until all the diazoketone has been consumed as determined by TLC analysis.
Enone–alkene cycloadditions often suffer from side reactions, e.g. those associated with the diradical intermediate. These side reactions can often be minimized by a judicious choice of reaction conditions. Dissolved oxygen is avoided since it is photoreactive. A variety of solvents can be used.