Ring closure Michael

A one-pot sequential Michael-Michael ring closure (MIMIRC) reaction using 2-cyclo-hexenone as the initial Michael acceptor allowed an effective construction of various polyfunctionalized polycyclic compounds (Scheme 50)210. 

Scheme 4. The synthesis of the decalin system by means of a Michael-Michael ring-closure sequence.

Scheme 10. A Michael-Michael-Michael ring-closure reaction sequence with complex 81.

Shioiri, T., and Irako, N., An efficient synthesis of the piperazinone fragment of pseudotheonamide Al via a stereoselective intramolecular Michael ring closure, Chem. Lett., 130, 2002. 

This is the basis of Posner s MIMIRC (Michael-Michael-Ring Closure) sequences.10 In the first example, the electrophile is a vinyl phosphonium salt 59. The first adduct 60 could cyclise, by the Wittig reaction, only to a cyclobutene 62 so it prefers to add a second molecule of 59 but the next intermediate 61 cyclises to a six-membered ring 63. 

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