Michael addition inter/intramolecular sequence

The substrate 292 was specifically designed to prepare five-membered systems via a sequence of inter- and intramolecular Michael additions. This option is viable when active Michael acceptors such as methyl vinyl ketone are used, otherwise competing Michael reactions between two molecules of 292 are difficult to avoid. The reaction proceeds through intermediate 293, which contains both a Michael donor and acceptor site and undergoes spontaneous conversion into the cyclic product 294. 

Several elegant examples of a double Michael addition sequence (inter-molecular followed by intramolecular) leading to complex fused-ring systems have been published this year (Scheme and Ghatak et al. ° describe... 

Besides this unique above-described process, there a numerous examples of inter- and intramolecular domino Michael/aldol processes in which the sequence is initiated by the addition of a metalorganic compound to an enone moiety. The Kamimura group [30] synthesized several five- to seven-membered thio- and hy-... 

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