Isothiourea-catalyzed formal enantioselective conjugate addition of benzophenone imines to β-fluorinated α,β-unsaturated esters

Abstract

The isothiourea-catalyzed enantioselective conjugate addition of 2-hydroxybenzophenone imine derivatives to α,β-unsaturated esters gives β-imino esters with up to 97 : 3 er.

Understanding divergent substrate stereoselectivity in the isothiourea-catalysed conjugate addition of cyclic α-substituted β-ketoesters to α,β-unsaturated aryl esters

“…Furthermore, the electron-deficient phenoxides generated in situ can be exploited to promote catalytic turnover, while their multifunctional nature can be exploited through acting as both Brønsted base and Lewis base. 24 Initially demonstrated in the enantioselective conjugate addition of nitroalkanes, 19 it has since been exploited using heterocyclic pro-nucleophiles, 21,25 malonates, 26 benzophenone imines, 27 as well as co-operative Pd-isothiourea promoted cascade reactions. 28 Conjugate addition and lactonisation processes using acylbenzothiazole and benzoxazole pronucleophile derivatives with α,β-unsaturated para -nitrophenyl esters has also been investigated synthetically.…”