138513-39-0Relevant academic research and scientific papers
Design, reactivities, and practical application of dialkylzinc hydride ate complexes generated in Situ from dialkylzinc and metal hydride. A new methodology for activation of NaH and LiH under mild conditions
Uchiyama, Masanobu,Furumoto, Shozo,Saito, Mariko,Kondo, Yoshinori,Sakamoto, Takao
, p. 11425 - 11433 (1997)
We designed various dialkylzinc hydride 'ate' complexes, prepared from dialkylzinc and metal hydride, and investigated the reactivities (and the transference aptitude of ligands) of these zincates toward benzophenone. The results clearly reveal that dimethylzinc hydrides are the most powerful and selective zincates for the reduction of the carbony1 group. This complex reagent turned out to be effective for the reduction of esters and amides as well as aldehydes and ketones to the corresponding alcohols and amines with good to excellent yields under mild conditions. Furthermore, the method was successfully used for the highly selective 1,2-reduction of α,β-unsaturated carbonyl compounds, the regioselective ring-opening reduction of epoxides, and the chemoselective reduction of aldehydes in the presence of ketones. We also discuss and clarify the active species and the mechanism of this reduction using the diastereoselective reductions of some carbonyl compounds with an adjacent chiral center. Also, this reducing system was found to constitute a powerful tool for the stereoselective synthesis of syn- and anti-1,2-diols. Moreover, we developed the catalytic version of this reducing system. The LiH-Me2Zn-ultrasound system proved to be effective not only for the catalytic reduction of the carbonyl compounds and epoxides but also for the partial reduction (the conversion) of carboxylic acids to aldehydes. This system is a very attractive method for several reasons (good availability, low cost, and easy operation) and would be particularly useful for large- scale reductions.
Additions of Organomagnesium Halides to α-Alkoxy Ketones: Revision of the Chelation-Control Model
Read, Jacquelyne A.,Yang, Yingying,Woerpel
supporting information, p. 3346 - 3349 (2017/07/13)
The chelation-control model explains the high diastereoselectivity obtained in additions of organometallic nucleophiles to α-alkoxy ketones but fails for reactions of allylmagnesium halides. Low diastereoselectivity in ethereal solvents results from no chelation-induced rate acceleration. Additions of allylmagnesium bromide to carbonyl compounds are diastereoselective using CH2Cl2 as the solvent even though rate acceleration is still absent. Stereoselectivity likely arises from the predominance of the chelated form in solution. Therefore, a revised chelation-control model is proposed.
