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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 ...
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.
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 ]
Diazo compounds are used as precursors to carbenes, which are generated by thermolysis or photolysis, for example in the Wolff rearrangement. (In this regard, they resemble diazirenes.) As such they are used in cyclopropanation for example in the reaction of ethyl diazoacetate with styrene. [22]
When in a cycloaddition charged or radical intermediates are involved or when the cycloaddition result is obtained in a series of reaction steps they are sometimes called formal cycloadditions to make the distinction with true pericyclic cycloadditions. One example of a formal [3+3]cycloaddition between a cyclic enone and an enamine catalyzed ...
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.
A diazo cross-coupling reaction has also been reported between ethyl diazoacetate and methyl phenyldiazoacetate using the rhodium catalyst [Rh 2 (OPiv) 4]. [ 5 ] A direct metal carbene dimerization has been used in the synthesis of novel Polyalkynylethenes [ 6 ]