{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T17:38:09Z","timestamp":1770226689799,"version":"3.49.0"},"reference-count":43,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T00:00:00Z","timestamp":1770163200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Chem."],"abstract":"<jats:p>\n                    The study concerned the stereoselective isomerisation of S2,S3-diethyl (\n                    <jats:italic>2R,3R,5R,6R<\/jats:italic>\n                    )-5,6-dimethoxy-5,6-dimethyl-1,4-dioxane-2,3-dicarbotioate to the isomer S2, S3-diethyl (\n                    <jats:italic>2R,3S,5R,6R<\/jats:italic>\n                    )-5,6-dimethoxy-5,6-dimethyl-1,4-dioxane-2,3-dicarbotioate via stable lithium and sodium enolates. For this purpose, enolate anions were generated using lithium diisopropylamide (LDA) and sodium isopropyl(trimethylsilyl)amide (NaPTA), using methanol as a proton source. Optimal stereoselectivity was achieved using 2.2 equivalents of LDA or NaPTA, yielding isomer ratios of 1:6.3 and 1:6.1, respectively, and good yields of 68% and 79%. The selectivity of the reaction was further increased in the presence of 10% (v\/v) HMPA or six equivalents of LiCl in systems with LDA, indicating the important role of metal complexation. A symmetrical bis(silyl enol ether) with a Z,Z configuration of double bonds was isolated from the enolate formed during the reaction, confirming the ordered geometry of the system. The observed stereoselectivity is explained by the non-equivalence of the two possible enolates and the chelation-controlled desymmetrisation of the dienolate. Both NaPTA and LDA enabled selective isomerisation without additives, with NaPTA proving particularly effective for related butanediacetal derivatives containing thioesters, providing &amp;gt;90% cis isomer yield for the mixed ester\u2013thioester substrate. These results show that NaPTA is an efficient and highly stereoselective base for the isomerisation of thioester-containing butanediacetals, expanding the possibilities of stereocontrolled enolate chemistry.\n                  <\/jats:p>","DOI":"10.3389\/fchem.2026.1750600","type":"journal-article","created":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T05:34:30Z","timestamp":1770183270000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Selective isomerization of 2,3-disubstituted butanediacetal esters and thioesters using lithium and sodium enolates: effects of bases and additives on stereoselectivity"],"prefix":"10.3389","volume":"14","author":[{"given":"Adam","family":"Drop","sequence":"first","affiliation":[{"name":"Faculty of Chemistry, Opole University","place":["Opole, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Magdalena","family":"Grzegolec","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry, Opole University","place":["Opole, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bo\u017cena","family":"Fr\u0105ckowiak-Wojtasek","sequence":"additional","affiliation":[{"name":"Faculty of Chemistry, Opole University","place":["Opole, Poland"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,2,4]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"e202400492","DOI":"10.1002\/chem.202400492","article-title":"Dual basicity and nucleophilicity of organosodium reagents in benzylic C-H additions of toluenes to diarylethenes and ketones","volume":"30","author":"Anderson","year":"2024","journal-title":"Chem. 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