1647-06-9Relevant articles and documents
Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
, p. 17305 - 17313 (2019/11/03)
The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
Stereoselective synthesis of α-methyl and α-alkyl ketones from esters and alkenes: Via cyclopropanol intermediates
Barysevich, Maryia V.,Kazlova, Volha V.,Kukel, Aliaksandr G.,Liubina, Aliaksandra I.,Hurski, Alaksiej L.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.
supporting information, p. 2800 - 2803 (2018/03/21)
Alkenes bearing a stereocenter in the allylic position were found to undergo Kulinkovich hydroxycyclopropanation with good diastereoselectivity. For the isomerization of the resulting cyclopropanols to diastereomerically enriched α-methyl ketones, a new mild regioselective method has been developed. A sequence of stereoselective cyclopropanation and cyclopropanol ring opening was successfully employed for the construction of the C20 stereocenter in steroids.
Selective Deprotection of Acetals with Me3SiCH2MgCl. Peterson-Type Olefination of Acetals
Chiang, Chao-Cheng,Chen, Yu-Huei,Hsieh, Yu-Tsai,Luh, Tien-Yau
, p. 4694 - 4697 (2007/10/03)
By employing the chelation strategy, treatment of an acetal of a contiguous diol with Me3SiCH2-MgCl liberates the corresponding diol regioselectively. In addition, acetals of different structural variety are transformed upon treatment with Me3SiCH2MgCl and ZnI2 into the corresponding olefination products in good yield.