DMSO is used as the reaction medium in published base-promoted acylations and Dieckmann cyclizations that form β-keto esters. These reactions create carbon–carbon bonds, but the route determines whether the bond forms between two molecules or closes a ring within one molecule.
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Separate the transformations before choosing a solvent
A classical Claisen ester condensation joins an enolate-derived carbon to an ester carbonyl, forming a β-keto ester after work-up. A Dieckmann condensation is the intramolecular version: a suitable diester closes to a cyclic β-keto ester.
Related Claisen-type acylations can use other acyl donors. In the 2016 study by Popović-Djordjević and co-workers, cyclic ketones were acylated with alkyl carbonates in DMSO-based systems. The same paper also examined Dieckmann ring formation from diesters. These are distinct substrate classes and should not be described as one identical recipe.
A DMSO-derived dimsyl anion is another chemical species. When it acts as a nucleophile, it can lead to sulfur-containing products rather than the β-keto ester expected from the intended enolate. Identifying the carbon nucleophile is therefore part of defining the reaction.
Compare a defined reaction system
The published work demonstrates selected acylation and ring-forming systems in DMSO. If a comparison also changes the base, additives or temperature, the outcome belongs to that complete system. It cannot establish a universal solvent-only yield advantage.
For a new substrate, follow the desired acylation or ring product alongside competing condensation, hydrolysis and other relevant impurities. Ring size and substitution can alter whether cyclization competes successfully with intermolecular chemistry.
Set water against base consumption and the intended reaction, then assess solids, viscosity and sampling. Changes in mixing or concentration can matter when comparing a small laboratory charge with process equipment.
Base compatibility and isolation remain decisive
Sodium hydride/DMSO mixtures have documented explosion hazards. A published high-yielding condensation is not a safety qualification for a new mixture or scale.
Establish the quench and the acid/base form needed for isolation. Confirm recovery, remaining starting material and residual DMSO in the isolated β-keto ester. Use those results, together with process-safety data, to decide whether the DMSO system suits the intended intermediate.
For a selected condensation route, YUJI can review DMSO sourcing against your established water, impurity and packaging requirements.