87413-33-0Relevant academic research and scientific papers
Three-Component [1 + 1 + 1] Cyclopropanation with Ruthenium(II)
Jankins, Tanner C.,Fayzullin, Robert R.,Khaskin, Eugene
, p. 2609 - 2617 (2018)
We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal-catalyzed carbene attack on olefins. Under the current protocol, various alcohols and esters are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C-C bonds, three or two new chiral centers and one new quaternary carbon center. Twenty-two examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multistep, linear routes that proceed with overall low yields and poor control of stereochemistry. Commercially available Ru(II) dehydrogenation catalysts, that were recently developed for the dehydrogenative synthesis of esters and amides from alcohol and amine substrates, were used in the reaction, with the best catalyst showing excellent activity at 0.2-1 mol % catalyst loading. Mechanistic investigation showed that in the case of alcohol substrates, the catalyst is only responsible for the first dehydrogenation step, and that the identity of the base and the countercation is crucial in achieving high yields. The catalyst is also required for the cyclopropanation of esters, although no dehydrogenation can proceed in this case, suggesting that substrates sensitive to H2 may be acylated prior to reaction.
CYCLOPROPANATION METHOD
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Paragraph 0013; 0072, (2019/03/05)
A cyclopropanation method includes reacting an alcohol, an ester, or an aldehyde with a sulfone in an organic solvent containing a base providing a counter cation to form a cyclopropane; and isolating the cyclopropane. When using the alcohol or ester, the organic solvent further contains a catalyst having an alcohol dehydrogenation activity.
