A Tandem Reaction Initiated by 1,4-Addition of Bis(iodozincio)methane for 1,3-Diketone Formation

Abstract

Treatment of an gamma-acyloxy-alpha,beta-unsaturated ketone with bis(iodozincio)methane leads to a novel tandem reaction consisting of three steps: (1) 1,4-addition of the dizinc reagent to the enone, which affords the corresponding zinc enolate of the beta-zinciomethylated ketone; (2) intramolecular nucleophilic attack by the enolate on the ester group; and (3) Grob-type fragmentation of the adduct, accompanied by elimination of the zinc alkoxide of allyl alcohol. The overall reaction gives 1,3-diketones efficiently.

Transition‐Metal‐Free Formal Decarboxylative Coupling of α‐Oxocarboxylates with α‐Bromoketones under Neutral Conditions: A Simple Access to 1,3‐Diketones

“…Recent improvements include the use of soft enolates in the presence of a Lewis acid and a weak base, [12] tin enolates [13] through a radical process, and kinetic zinc enolates using bis(iodozincio)methane. [14] The decarboxylative coupling strategy would certainly provide an attractive alternative route to 1,3-diketone compounds. Herein, we report that a-oxocarboxylates undergo reaction with a-bromoketones to afford 1,3-diketones in the absence of a transition-metal catalyst [Eq.(2)].…”

Transition‐Metal‐Free Formal Decarboxylative Coupling of α‐Oxocarboxylates with α‐Bromoketones under Neutral Conditions: A Simple Access to 1,3‐Diketones

“…The rigorous reaction conditions required and hence limited substrate scope are major drawbacks for this reaction. Recent improvements include the use of soft enolates in the presence of a Lewis acid and a weak base,12 tin enolates13 through a radical process, and kinetic zinc enolates using bis(iodozincio)methane 14. The decarboxylative coupling strategy would certainly provide an attractive alternative route to 1,3‐diketone compounds.…”

Design of Molecular Transformations Based on the Concerted Function of Two Zinc Atoms in Bis(iodozincio)methane

“…A tandem reaction consisting of three sequential steps was proposed as a plausible mechanism. 25,27 The results of DFT calculations for the reaction of (2E)-4-oxobut-2-en-1-yl formate with bis(chlorozincio)methane are shown in Scheme 13. 25 The reactants first form an association complex CP1 bearing two Zn···O bridges between the bis(chlorozincio)methane moiety and the substrate.…”