Manganese(III) Acetate-mediated Alkylation of 1,3-Dicarbonyls to Form Tricarbonyl Compounds Bearing a Quaternary Carbon Centre

Abstract

1,3-Dicarbonyl compounds including ethyl 2-methylacetoacetate can be efficiently alkylated with enol ethers or enol esters in the presence of manganese(III) acetate. These intermolecular radical addition reactions can be used to form sterically congested quaternary carbon centres in excellent yield (81-97%).

Intermolecular Enolate Heterocoupling: Scope, Mechanism, and Application

“…The direct, convergent synthesis of unsymmetrical 2,3-disubstituted-1,4-dicarbonyl compounds from two carbonyl subunits has proven extremely difficult; several methods for the synthesis of hypothetical succinate 1 are depicted in Figure . , Efficient, enantioselective syntheses of such entities have escaped synthetic grasp, in spite of their presence in countless natural products and innumerable medicinal remedies. All of the methods depicted suffer from one or more of the following limitations: multistep sequences, installation of requisite disposable functionality on one or both of the monomers, and stereoselectivity problems with prefunctionalization methods and/or during the union of the two monomers.…”

Cerium‐Catalyzed, Aerobic Oxidative Synthesis of 1,2‐Dioxane Derivatives from Styrene and Their Fragmentation into 1,4‐Dicarbonyl Compounds

“…Yields for this class of substrates seem to be dependent on the steric demand of the α‐alkyl substituent. This is illustrated by the decrease in the order H ( 2h ), Me ( 2i ),16 Bn ( 2k ),17 Et ( 2j ) from 72 % to 42 % yield. Replacement of the acetyl group in 2h by a benzoyl residue in 2l 18 lowered the yield from 72 % to 56 %.…”

3 Transition metals in organic synthesis : Part (ii) Stoichiometric applications

“…82 Parsons and co-workers have reported an efficient Mn(OAc) 3 -mediated procedure for the alkylation of 1,3-dicarbonyls to form tricarbonyl compounds bearing a quaternary carbon centre. 83 The Mn(OAc) 3 reagent has been used to mediate the oxidative coupling of phenylhydrazines with furan and thiophene to provide novel hetero biaryl coupled products 84 and in the tandem oxidation of various αand β-alkoxy α,β-unsaturated ketones. 85 A Mn(OAc) 3 -mediated addition of malonic acid (instead of acetic acid) to various cinnamic esters is reported as a useful one-pot procedure for the synthesis of functionalised trans-3,4disubstituted-γ-butyrolactones.…”