Facile synthesis of 2-methylenecyclobutanones via Ca(OH)<sub>2</sub>-catalyzed direct condensation of cyclobutanone with aldehydes and (PhSe)<sub>2</sub>-catalyzed Baeyer–Villiger oxidation to 4-methylenebutanolides
(2-MCBones), used to be difficult to access, but can now be easily achieved by a green and stereospecific Ca(OH)2-catalyzed direct and simple aldol condensation of cyclobutanone and aldehydes under mild conditions. The obtained (E)-2-MCBones should be a class of potentially useful building blocks in synthesis as they could readily undergo an interesting (PhSe)2-catalyzed Baeyer–Villiger (BV) oxidation
2-亚甲基环丁酮(2-MCBones)过去很难获得,但现在可以通过在绿色和立体定向Ca(OH)2催化下在温和条件下环丁酮和醛的直接简单的羟醛缩合直接实现。所获得的(E)-2-MCBones应该是一类在合成中潜在有用的结构单元,因为它们在室温下很容易通过H 2 O 2进行有趣的(PhSe)2催化的Bayerer -Villiger(BV)氧化而得到通用的4-亚甲基丁醇化物。机理研究表明,BV反应最有可能通过苯硒代过氧苯甲酸酐[PhSe(O)O] 2的初步形成而进行。O然后转化为苯硒酸过氧酸PhSe(O)OOH作为活性氧化剂,然后将其选择性添加到2-MCBones的C O键中,然后进行选择性的C-C键裂解和重排,得到4-亚甲基丁醇化物。
Proline and secondary amine co-catalyzed condensation of cyclobutanone with aldehydes: a facile access to 2-methylenecyclobutanones under near neutral conditions
作者:Lei Yu、Jie Luan、Lin Xu、Yuanhua Ding、Qing Xu
DOI:10.1016/j.tetlet.2015.09.088
日期:2015.10
Using L-proline catalyst, the useful building blocks 2-methylenecyclobutanones (2-MCBones) are now easily accessible in moderate to good yields through the condensation of the commercially available cyclobutanone with the abundant aldehydes. Compared with the literature reports, this methodology provides a direct synthesis of 2-MCBones from accessible starting materials and employs near neutral catalysts, which are stable to the acidic impurities in substrates. (C) 2015 Elsevier Ltd. All rights reserved.
Selective Asymmetric Hydrogenation of Four-Membered <i>Exo</i>-α,β-Unsaturated Cyclobutanones Using RuPHOX–Ru as a Catalyst
The selective asymmetric hydrogenation of four-membered exo-α,β-unsaturated cyclobutanones has been achieved for the first time using RuPHOX-Ru as a catalyst, providing four-membered exo-cyclic chiral allylic alcohols in high yields and with up to 99.9% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C), and the resulting products can be transformed
使用RuPHOX-Ru作为催化剂,首次实现了四元外-α,β-不饱和环丁酮的选择性不对称加氢,以高收率和高达99.9%的产率提供了四元外环手性烯丙基醇。 ee。该反应可以以克级进行,具有相对较低的催化剂负载量(最高10000 S / C),并且所得产物可以转化为几个生物活性分子。
Rh(I)-catalyzed ring-opening of cyclobutanols via C–C bond activation: Synthesis of cis-olefin with a remote aldehyde
作者:Yu Nie、Jianzhong Chen、Wanbin Zhang
DOI:10.1016/j.tet.2019.130563
日期:2019.9
A Rh(I)-catalyzed ring-opening of cyclobutanols has been developed with ring opening products bearing cis-olefin and a remote aldehyde. Various substrates bearing different substituted aryl groups, heterocyclic groups and alkyl groups were compatible with the mild reaction conditions. A β-C elimination pathway was proposed based on the results of preliminary mechanistic studies.