Asymmetric C-H Activation of a Benzyl Silyl Ethers

Significance

A Rh-catalyzed intermolecular C-H functionalization of benzyl silyl ethers using a phenyldiazoacetate afforded syn-2,3-diaryl-3-siloxy­propionates in good stereoselectivity. Substituents at the para-position with different electronic properties were compatible. Both chiral auxiliary and chiral catalyst strategies were applied in the synthesis. In the former process, a readily available (S)-lactate was used as the auxiliary, that can be removed by DIBAL reduction. In the latter case, the chiral catalyst Rh₂[(S)-PTTL]₄ was optimal, providing better diastereoselectivity and enantioselectivtity in a simpler fashion.