The enantioselective incorporation of alkyl groups in thiochromones was realized for
the first time by a Cu/(R,S)-PPF-P
t
Bu2-catalyzed conjugate addition of Grignard reagents to thiochromones. With this method,
a series of 2-methylthiochromanones were obtained in good yields (up to 96% yield)
with moderate-to-good ee values (up to 87% ee). The established method expedites the
synthesis of a large library of chiral thiochromanones for further synthetic applications
and biological studies.
Key words
asymmetric synthesis - Grignard reagents - conjugate addition - thiochromanones -
flavonoids