Vitamin C and isovitamin C derived chemistry. 3. Chiral butenolides via efficient 2,3-didehydroxylations of L-gulono-, D-mannono-, and D-ribono-1,4-lactones

Abstract

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Regio- and Diastereoselective Allenylation of Aldehydes in Aqueous Media: Total Synthesis of (+)-Goniofufurone1

“…To effect a reductive elimination, the crude polyol mixture was directly treated with concentrated sulfuric acid in acetic anhydride 28 to afford the peracetylation product 34 (calculated 75% yield from 33), which showed decomposition on silica gel. Subsequent treatment of the peracetylation product 34 with sodium bisulfite/sodium sulfite 29 in aqueous methanol cleanly afforded the desired R,β-unsaturated γ-lactone, as shown by the 1 H NMR measurement of the crude product. To remove the acetyl protecting groups, the product was stirred in methanolic HCl for 2 days.…”

“…1 H NMR (400 MHz, CDCl3, ppm): δ 1.33 (s, 3H), 1.50 (s, 3H), 2.66-2.74 (m, 2H), 4.81 (d, J ) 3.6 Hz, 1H), 4.83 (d, J ) 4.0 Hz, 1H), 4.95-5.02 (m, 1H), 5.96 (d, J ) 4.0 Hz, 1H). 13 (29). A suspension of 27 (98.9 mg, 0.62 mmol), 3-bromo-1-propynylbenzene (647.7 mg, 3.32 mmol), and indium (286 mg, 2.49 mmol) in 0.1 N hydrochloric acid/ethanol (1:9; 4 mL) was stoppered and stirred vigorously at room temperature overnight.…”

Exploring the Boundaries of “Practical”: De Novo Syntheses of Complex Natural Product-Based Drug Candidates

“…16 Finally, the synthesis of the last required fragment of halichondrin B took place according to procedures established by the group. 22 The synthesis commenced with the 11-step transformation of butenolide 27, readily produced from ascorbic acid, 23 into compound 28. Eight additional steps then yielded fragment 12 in a total of 19 steps (Scheme 4).…”

Asymmetric Synthesis of Styryl-Lactones

“…Ozonolysis of 113, followed by reduction provided the desired alcohol and the other diastereoisomer in a 75:25 ratio. The required alcohol (70% pure) was peracetylated and treated with sodium bisulfite/sodium sulfite [58] to afford the corresponding α,β-unsaturated-γ-lactone (70% pure). Deacetylation with spontaneous cyclization and purification by thin layer chromatography, afforded (+)-goniofufurone (27) …”