Asymmetric Dihydroxylation of β,γ‐Unsaturated Carboxylic Esterswith Trisubstituted C=C Bonds – Enantioselective Syntheses of Trisubstituted γ‐Butyrolactones

Abstract

Keywords: Asymmetric dihydroxylation / Butyrolactones / β,γ-Unsaturated carboxylic esters / Stereoselective synthesis / Wolff rearrangement β,γ-Unsaturated esters with stereodefined trisubstitued C=C double bonds were prepared by the Arndt-Eistert homologation of α,β-unsaturated carboxyl halides, by two-step methoxycarbonylation of allylbarium reagents, by deconjugation of α,β-unsaturated esters, and by Horner-Wadsworth-Emmons variants of the Stobbe condensation. Sharpless asymmetric dihydroxylation of the β,γ-unsaturated esters, followed by spontaneous cyclization, afforded β-hydroxy-γ-lac-

Total Synthesis of Gracilioether F: Development and Application of Lewis Acid Promoted Ketene–Alkene [2+2] Cycloadditions and Late‐Stage CH Oxidation

“…[9] Treatment of acid chloride 9 b with Et 3 N led to rapid formation of the ketene at 22 8C. The slow rate of ketene generation from acid chloride 9 a is likely due to the poorly acidic g-protons.…”

Synthesis and absolute configuration of the male aggregation pheromone of the stink bug Erysarcoris lewisi (Distant), (2Z,6R,1′S,5′S)-2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol

“…11 Alcohol 11, which was prepared from (R)-citronellal in two steps, 10 was treated with methanesulfonyl chloride in the presence of pyridine to give allyl chloride 12 in 85% yield. 18 Conversion of 12 into the corresponding Grignard reagent 13, was followed by treatment with (R)-epichlorohydrin 14 in the presence of CuI to give the key intermediate 15 in 50% yield. 19 Chlorohydrin 15 was subjected to Hodgson's intramolecular cyclopropanation by treatment with lithium 2,2,6,6-tetramethylpiperidide to afford (6R,1 0 S,4 0 R,5 0 R)-3 0 in 95% yield as a single diastereomer.…”

Use of Silver Carbonate in the Wittig Reaction

“…26 Both reagents gave comparable results. Compounds 8a , 14,27 8b , 28,29 8c , 30 8d , 31,32 8e , 33 8f , 34 8g , 35,36 , 8h ,25 8i , 21 and 8l 4 are known. Their NMR spectra were identical to the referenced values.…”