3-Alkyl-1, 2-cyclopentanediones by Negishi cross-coupling of a 3-bromo-1, 2-cyclopentanedione silyl enol ether with alkylzinc reagents: an approach to 2-substituted carboxylic acid γ-lactones, homocitric and lycoperdic acids. Issue 49 (9th December 2015) - Paju, Anne
Abstract: Negishi cross-coupling of the silyl-protected 3-bromoenol of 1, 2-cyclopentanedione with primary and secondary alkylzinc reagents using Pd-catalysts affords 3-alkyl substituted 1, 2-cyclopentanediones in good yield. The method was applied to obtain 3-methylalkoxycarbonyl- and 3(2-Boc-aminoethyl)-alkoxycarbonyl-1, 2-cyclopentanediones—homocitric and lycoperdic acid precursors. Homocitric and lycoperdic acids were synthesized using asymmetric oxidation with the Ti(O i Pr)4 /tartaric ester/ t BuOOH complex in two steps from the obtained precursors. Graphical abstract: