NHC‐catalysis proto(n)type: The title reaction produces 21 different chroman‐4‐one‐type products in good yields and excellent enantioselectivities, in each case building up a new all‐carbon quaternary stereocenter (see scheme). Based on DFT calculations a mechanistic scenario involving proton transfer, possible transition states, and a mode of enantioinduction is presented.
Cobalt-Catalyzed Annulation of Salicylaldehydes and Alkynes to Form Chromones and 4-Chromanones
作者:Junfeng Yang、Naohiko Yoshikai
DOI:10.1002/anie.201510999
日期:2016.2.18
A unique cobalt(I)–diphosphine catalytic system has been identified for the coupling of salicylaldehyde (SA) and an internal alkyne affording a dehydrogenative annulation product (chromone) or a reductive annulation product (4‐chromanone) depending on the alkyne substituents. Distinct from related rhodium(I)‐ and rhodium(III)‐catalyzed reactions of SA and alkynes, these annulation reactions feature
N-Heterocyclic Carbene-Catalyzed Hydroacylation of Unactivated Double Bonds
作者:Keiichi Hirano、Akkattu T. Biju、Isabel Piel、Frank Glorius
DOI:10.1021/ja906361g
日期:2009.10.14
An intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation of unactivated double bonds is reported. Systematic variation of the catalyst structure revealed an N-mesitylthiazolylidene annulated with a seven-membered ring to be especially reactive. This NHC enables a unique C-C bond-forming reaction to afford substituted chroman-4-ones in moderate to excellent yields, even ones containing all-carbon quaternary centers.
Sakata; Hashimoto, Yakugaku Zasshi/Journal of the Pharmaceutical Society of Japan, 1959, vol. 79, p. 872