title: Copper(II)-catalyzed asymmetric henry reaction of o-alkynylbenzaldehydes followed by gold(I)-mediated cycloisomerization: an enantioselective route to chiral 1H-isochromenes and 1,3-dihydroisobenzofurans.
abstract: By combining the copper(II)-catalyzed asymmetric Henry reaction of o-alkynylbenzaldehydes with subsequent gold(I)-catalyzed cycloisomerization, optically active 1H-isochromenes and 1,3-dihydroisobenzofurans were successfully synthesized in good overall yields with good to excellent enantioselectivities (up to 98%). Various substrates were investigated, and a correlation between the regioselectivity and electronic nature of the substrates was studied. The substrates with electro-donating groups at the alkynyl moiety preferred a 6-endo-dig manner to generated 1H-isochromenes 3 as main products (up to >30:1) while the ones with electron-withdrawing groups were inclined to undergo 5-exo-dig cyclization to form 1,3-dihydroisobenzofurans 4 (up to 1:5).
authors.affiliation: School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan 430074, China.
authors.forename: Dengfu
authors.initials: D
authors.lastname: Lu
authors.forename: Yirong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yajun
authors.initials: Y
authors.lastname: Li
authors.forename: Shaobai
authors.initials: S
authors.lastname: Yan
authors.forename: Yuefa
authors.initials: Y
authors.lastname: Gong
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D006046:Gold / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001547:Benzaldehydes; D001578:Benzopyrans; D006046:Gold; D003300:Copper