Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• closure (Scheme 1). A plausible mechanism for the cyclization of compounds 7 is the Darzens reaction to episulfide, followed by Barton–Kellogg-type reaction with triphenylphosphine and elimination of triphenylphosphine sulfide. Compound 8 showed lower germination activity than KAR1 [22], but achieved IC50

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• quantitatively converted to phosphorothioate ONs by carboxyesterase-mediated deacylation followed by the removal of the resulting S-(2-mercaptoethyl) group by cyclization to episulfide. For S-acyloxymethyl phosphorothiolates, hydrolysis of the ester catalyzed by the enzymes was followed by release of

The Eschenmoser coupling reaction under continuous-flow conditions

• Sukhdeep Singh,
• J. Michael Köhler,
• Andreas Schober and
• G. Alexander Groß

Beilstein J. Org. Chem. 2011, 7, 1164–1172, doi:10.3762/bjoc.7.135

• desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given. Keywords: activation energy; episulfide; flow chemistry; keto imine; kinetics; S-alkylation; sulfide contraction

• ; triisopropyl phosphite; Introduction The Eschenmoser coupling [1][2] is a reaction method that yields β-enaminocarbonyl derivatives of type 4 by the elimination of sulfur (sulfide contraction) from an episulfide intermediate (Scheme 1). The reaction was described for the first time by Knott in 1955 [3] and

• construction of the episulfide intermediate 6, which requires base catalysis (B). The sulfur extraction from the episulfides 6 or 8 yields the desired β-enaminocarbonyl derivative 4 or 9. However, the detailed reaction mechanism for the sulfur extraction step has not yet been fully proven and obviously depends