Catálise assimétrica na ciclopropanação de olefinas

Abstract

ASYMMETRIC CATALYSIS IN THE CYCLOPROPANATION OF OLEFINS.The main methodologies in the asymmetric cyclopropanation of alkenes with emphasis on asymmetric catalysis are covered. Exemples are the Simmons-Smith reaction, the use of diazoalkanes and reactions carried out by decomposition of α-diazoesters in the presence of transition metals.

Density functional theory study of the mechanism of zinc carbenoid promoted cyclopropanation of allenamides

“…The critical issues in metal-mediated SS reactions that should be addressed include the basic mechanisms of the cyclopropanation process, the coordination between the metal atom and the heteroatom of the leading group, 26 the strain and steric effects in the reactant complex and the aggregation effects of the metal carbenoids and substrates. 24,27 On the basis of results from previous studies on (halomethyl)metal carbenoid-mediated cyclopropanation of olefins 28,29 and alkoxides, the asymmetric cyclopropanation reaction systems using other kinds of metal complex catalysts or modified olefins have also been explored. [30][31][32][33][34][35][36][37][38] Among these other reaction systems, a great deal of experimental and computational effort has been directed toward the cyclizations of allenes and their derivatives.…”

Ethyl Diazoacetate

“…Ethyl diazoacetate (EDA; C 4 H 6 N 2 O 2 ) is a yellow liquid with a pungent odor used mainly in organic synthesis for cyclopropanation of unsaturated compounds, but also for cyclopropanation, cycloaddition reactions, synthesis of triazoles and pyrazolines, and insertion reactions (Scheme 1). [1][2][3] The use of EDA is also studied in continuous-flow methods with homogeneous and heterogeneous catalysis with transition metals, for example, in selective olefination of aldehydes using copper(II) complexes. 3,4 It can be prepared through reaction between sodium nitrite and glycine ethyl ester hydrochloride in the presence of diluted sulfuric acid, ethanol, and sodium acetate.…”

“…Commercially, it is available in dichloromethane or toluene solutions since it is flammable, shock sensitive, and toxic. 1,2 Nevertheless, EDA is an important synthon for organic synthesis (…”