Hydrocobaltation–dehydrocobaltation reactions in synthesis: a new approach to the controlled cross-coupling between sp<sup>2</sup>carbon centres leading to functionalised alkenes
作者:Harcharan Bhandal、Gerald Pattenden
DOI:10.1039/c39880001110
日期:——
Cross-couplingreactionsbetween two alkenes, leading to newfunctionalisedalkenes, can be brought about via‘hydrocobaltation’ of one of the alkenes followed by irradiation of the resulting organocobalt reagent in the presence of the second alkene substrate.
Synthesis of α‐Branched Enones via Chloroacylation of Terminal Alkenes
作者:Jungwon Kim、Sven Müller、Tobias Ritter
DOI:10.1002/anie.202309498
日期:2023.12.4
show the conversion of unactivated alkenes into α-branched α,β-unsaturated ketones (enones) and esters. Regioselective chloroacylation with acyl chlorides and chloroformates takes place under cooperative nickel/photoredox catalysis. Subsequent HCl elimination provides enones and α,β-unsaturated esters that are not accessible via the conventional acylation approaches that provide the other, linear constitutional
compounds to afford valuable chiral β-amino acid derivatives (up to >99:1 e.r.) using dioxazolones as a robust amino source. A wide range of alkyl-substituted olefins conjugated to esters, amides, thioesters, and ketones were successfully amidated at the β-position with excellent enantioselectivity for the first time. Combined experimental and computational mechanistic studies supported our working hypothesis
By means of an intramolecular Baylis-Hillman reaction the cyclopentene derivative 1 has been formed from 2. Asymmetric induction is low (entry 12, table 1). In the sixmembered ring example 9 --> 10 the yield is only 17% - 23% (entries 1 and 2, table 2).
A new sequential reductive coupling process promoted by samarium(II) iodide is described. Cascade epoxide ring opening and ketyl radical olefin cyclization leads to a variety of cis-1,3-cyclopentanediols and cis-1,3-cyclohexanediols in good yields and with high diastereoselectivity.