Two reaction pathways were elaborated for the practical and convenient synthesis of the title compounds. The first route applies a bromination-dehydrobromination sequence to introduce the double bond into 1-alkoxycarbonyl-2-oxocycloalkylacetic and propionic esters (4a-c, 7a, b). The application of 2,6-lutidine for dehydrobromination of α-bromocycloalkanones diesters (5a-c, 8a, b) provides sufficient selectivity to carry out this step without affecting the sensitive ester group. Alternative pathways, involving Michael reaction of diethyl 2-acetylsuccinate or -glutarate with acrolein and subsequent intramolecular aldol condensation, are presented in the case of cyclohex-2-enone derivatives 2a, b.
- Aldol condensation
- Cyclopent-2-enone and cyclohex-2-enone derivatives
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