40 research outputs found
Morita-Baylis-Hillman Reaction of Masked 5-Alkylidene-2-cyclopentenones: General Entry to 5-Alkylidene-2-(hydroxyalkyl)-2-cyclopentenones
Electrophilic Difluoro(phenylthio)methylation: Generation, Stability, and Reactivity of α‑Fluorocarbocations
Electrophilic difluoro(phenylthio)methylation of allylsilanes has been achieved using bromodifluoro(phenylthio)methane (PhSCF<sub>2</sub>Br) and silver hexafluoroantimonate (AgSbF<sub>6</sub>). The structural assignment and observation of α-fluorocarbocation were substantiated by NMR and theoretical calculations. Detailed mechanistic and electronic studies have provided a fundamental understanding of the reactivity and stability of the difluoro(phenylthio)methylium cation (PhSCF<sub>2</sub><sup>+</sup>)
Benzotriazole-Mediated [2,3]-Wittig Rearrangement. General and Stereocontrolled Syntheses of Homoallyl Alcohols and β,γ-Unsaturated Ketones
Asymmetric Total Syntheses of (+)-Mycoepoxydiene and Related Natural Product (-)-1893A: Application of One-Pot Ring-Opening/Cross/Ring-Closing Metathesis to Construct Their 9-Oxabicyclo[4.2.1]nona-2, 4-diene Skeleton
Aldol Reactions at Dioxanes Derived From Tartaric Acid. A Total Synthesis of (+)-Nephrosteranic Acid
Asymmetric Total Syntheses of Megacerotonic Acid and Shimobashiric Acid A
The asymmetric total syntheses of the α-benzylidene-γ-butyrolactone natural products megacerotonic acid and shimobashiric acid A have been accomplished in nine and 11 steps, respectively, from simple, commercially available starting materials. The key step for each synthesis is the (arene)RuCl(monosulfonamide)-catalyzed dynamic kinetic resolution-asymmetric transfer hydrogenation (DKR-ATH) of racemic α,δ-diketo-β-aryl esters to establish the absolute stereochemistry. Intramolecular diastereoselective Dieckmann cyclization forms the lactone core, and ketone reduction/alcohol elimination installs the α-arylidene. [Image: see text