Cinchona alkaloid-based domino Michael reactions

In 2012, Maikov and coworkers reported a similar strategy for the synthesis of spirocyclopropanes bearing two quaternary centers. In this approach, 2-chloroacetoacetates (49) reacted with 17c via a Michael/a-alkylation domino reaction (Scheme 10.16) [22]. The reaction was catalyzed by bifunctional Brpnsted Acid-Lewis base X. The final spirocyclopropanes 50 were obtained under optimized conditions in good yields and excellent diastereo and enantioselectivities. A similar approach was developed by the same research group using 3-chlorooxindoles (51) instead of 2-chloroacetoacetates [23]. This time, the catalyst was a bifiinctional squaramide-tertiary amine XI derived from cinchona alkaloids, rendering the final spirocyclopropanes 52 in good yields and excellent enantioselectivities. 

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