Preparation of five- and six- membered cyclic ketones by the palladium-catalyzed cyclization reaction. Application to methyl dihydrojasmonate synthesis

Add time:08/19/2019    Source:sciencedirect.com

Methyl 3-oxo-8-phenoxy-6-octenoate (1) was cyclized using Pd(OAc)2-PPh3 as a catalyst to give 2-carbomethoxy-3-vinylcyclopentanone (2) and 2-carbomethoxy-4-cycloheptenone (3). The former was the main product in acetonitrile. 2-Alkylated 3-oxo-8-phenoxy-6-octenoates were converted mainly to the five-membered ketones. Based on this cyclization method, methyl dihydrojasmonate (8) was prepared from methyl 2-pentyl-3-oxo-8-phenoxy-6-octenoate (5). Methyl 3-oxo-9-phenoxy-7-nonenoate (10) was subjected to the palladium-catalyzed cyclization to afford 2-carbomethoxy-3-vinylcyclohexanone (11) selectively without forming the eight-membered ketone (12).

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