ChemInform Abstract: A Michael Addition‐Induced Favorskii Rearrangement.

Abstract

090ChemInform Abstract The reaction of 6-chloro-2-isopropylidenecyclohexanone (Ia) with NaOMe affords the product (IIa), which results by simple substitution, and the methyl 2-isopropylidene-1-cyclopentanecarboxylate (IIIa) as the main product along with the methyl trans-(1-methoxy-1-methylethyl)-1-cyclopentanecarboxylate (IVa). The products (IIIa) and (IVa) are formed by Favorskii rearrangements of the cyclohexane skeleton. These rearrangements are started by a Michael addition of NaOMe to the carbon-carbon double bond of (Ia). The analogous reactions of 2-ethylidene-(Ib) or 2-benzylidene-6-chlorocyclohexanone (Ic) with NaOMe afford the products (IVb) -erythro:threo = 20:18 -and (Vb) or (IVc) -erythro:threo = 33:29 -and (VIc), which are all formed by Michael addition-induced Favorskii rearrangements.