posted on 2021-08-05, 12:36authored byYuk-Cheung Chan, Xinyan Wang, Ying-Pong Lam, Jonathan Wong, Ying-Lung Steve Tse, Ying-Yeung Yeung
A catalyst-controlled
enantiodivergent bromolactonization of olefinic
acids has been developed. Quinine-derived amino-amides bearing the
same chiral core but different achiral aryl substituents were used
as the catalysts. Switching the methoxy substituent in the aryl amide system from meta- to ortho-position results in a complete switch
in asymmetric induction to afford the desired lactone in good enantioselectivity
and yield. Mechanistic studies, including chemical experiments and
density functional theory calculations, reveal that the differences
in steric and electronic effects of the catalyst substituent alter
the reaction mechanism.