Transition Metal‐Free sp
<sup>3</sup>
−sp
<sup>3</sup>
Carbon‐Carbon Coupling between Benzylboronic Esters and Alkyl Bromides
作者:Richard W. Russell、Timothy J. Barker
DOI:10.1002/ejoc.202100361
日期:2021.5.20
An sp3−sp3 transition metal-free coupling between benzylic boronic esters and alkyl halides has been demonstrated. The boronate nucleophile reacts selectively with alkylbromides in the presence of alkyl chlorides and epoxides. The boronate can be attached to a primary, secondary and tertiary carbon center, providing the desired coupled products in good to excellent yields.
The total synthesis of a series of new carolacton derivatives that mainly lack selected methyl substituents along the polyketide backbone is reported. Their inhibitory activity towards bacterial biofilms revealed that selective removal of the methyl group at C10 does not have a major effect on biological activity, whereas additional removal of the methyl group at C14 in carolacton results in a large
Copper(I)-Catalyzed Boryl Substitution of Unactivated Alkyl Halides
作者:Hajime Ito、Koji Kubota
DOI:10.1021/ol203413w
日期:2012.2.3
Borylation of alkyl halides with diboron proceeded in the presence of a copper(I)/Xantphos catalyst and a stoichiometric amount of K(O-t-Bu) base. The boryl substitution proceeded with normal and secondary alkyl chlorides, bromides, and iodides, but alkyl sulfonates did not react. Menthyl halides afforded the corresponding borylation product with excellent diastereoselectivity, whereas (R)-2-bromo-5-phenylpentane gave a racemic product. Reaction with cyclopropylmethyl bromide resulted in ring-opening products, suggesting the reaction involves a radical pathway.