Remote asymmetric induction using neighboring group participation of a sulfenyl group
摘要:
2-[1-(Mesitylthio)alkyl]benzaldehydes and their dimethyl acetals react with silylated carbon nucleophiles under Lewis acidic conditions to give the corresponding aldol adducts with high diastereoselectivity, and in some cases, the products were obtained as almost a single diastereomer. Such a high diastereoselectivity is interpreted as the result of the 1,4-remote asymmetric induction through the benzene ring from the chiral ortho substituents of the substrates to the reaction centers. In the same manner, gamma-mesitylthiolated aliphatic aldehydes and their acetals also react diastereoselectively to give the corresponding aldol adducts. In this case, the remote asymmetric induction occurs without the aid of a rigid benzene ring on the main chain of the substrates. In both reactions, a 5-membered cyclic sulfonium ion intermediate is thought to exist in the reaction pathway, which is formed by the intramolecular S(N)2 reaction of the mesitylthio group, namely, the neighboring group participation of the sulfenyl group.
Remote asymmetric induction using neighboring group participation of a sulfenyl group
摘要:
2-[1-(Mesitylthio)alkyl]benzaldehydes and their dimethyl acetals react with silylated carbon nucleophiles under Lewis acidic conditions to give the corresponding aldol adducts with high diastereoselectivity, and in some cases, the products were obtained as almost a single diastereomer. Such a high diastereoselectivity is interpreted as the result of the 1,4-remote asymmetric induction through the benzene ring from the chiral ortho substituents of the substrates to the reaction centers. In the same manner, gamma-mesitylthiolated aliphatic aldehydes and their acetals also react diastereoselectively to give the corresponding aldol adducts. In this case, the remote asymmetric induction occurs without the aid of a rigid benzene ring on the main chain of the substrates. In both reactions, a 5-membered cyclic sulfonium ion intermediate is thought to exist in the reaction pathway, which is formed by the intramolecular S(N)2 reaction of the mesitylthio group, namely, the neighboring group participation of the sulfenyl group.