Читать книгу Catalytic Asymmetric Synthesis - Группа авторов - Страница 27

Domino reactions offer a powerful way to construct complex structures in a single reaction vessel; each reaction occurs as a consequence of the intermediates generated in previous steps without changing any reaction conditions [49]. Most of the asymmetric domino reactions are composed of two reactions occurring one after the other. Organocatalysts can also be effective in domino reactions [50]. List [51], MacMillan [52], and Jørgensen [44] reported the domino iminium/enamine reaction at the same time in 2005. List reported conjugate reduction−Michael cyclization of enal enones, in which treatment of the enal enone with Hantzsch dihydropyridine in the presence of a catalytic amount of MacMillan’s catalyst provided cyclic keto aldehydes with excellent enantioselectivity (Eq. 1.24). MacMillan reported an iminium/enamine domino reaction employing several nucleophiles and electrophiles catalyzed by MacMillan’s catalyst (Eq. 1.25). Jørgensen reported that a domino reaction of conjugate addition of thiol and amination, which was catalyzed by diarylprolinol silyl ether, afforded 1,2‐aminothiol derivatives in nearly optically pure form (Eq. 1.26).

(1.24)

(1.25)

(1.26)