A Unified Strategy for the Total Synthesis of the Angucycline Antibiotics SF 2315A, Urdamycinone B, and the Shunt Metabolite 104–2

Abstract

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Total Synthesis of Aryl C-Glycoside Natural Products: Strategies and Tactics

“…As long as the glycosyl donor A is sufficiently activated by Lewis acids or other reaction promoters, this facile process proceeds even at −78 °C (typically employed in the initial studies). Thus, various glycosyl donors, including glycosyl fluorides as above, ,,,− and glycosyl acetates, ,,,− 1-OH sugars, − methyl glycosides, ,, thioglycosides, glycosyl imidates, − glycosyl phosphates, ,, and glycals, , have been used in combination with suitable activators (Scheme ).…”

Synthesis of orthogonally protected d-olivoside, 1,3-di-O-acetyl-4-O-benzyl-2,6-dideoxy-d-arabinopyranose, as a C-glycosyl donor

“…All moisture sensitive reactions were performed under a nitrogen atmosphere. (22) p-Toluenesulfonyl chloride (8.66 g, 45.4 mmol) was added to a mixture of thioglycoside (21) (9.90 g, 36.0 mmol) in dichloromethane (75 mL) and pyridine (75 mL) at 0 C. The mixture was slowly warmed to room temperature and stirred overnight. The solvent was removed in vacuo and the residue was dissolved in dichloromethane.…”

“…20 Other groups have utilised C-glycosidic naphthoquinones as dienophiles for the synthesis of angucycline antibiotics. Sulikowski et al 21,22 used C-glycosyl dienophile 8 in their elegant synthesis of urdamycinone B (4), while Matsuo et al 23,24 used the unprotected C-glycoside 9 as a dienophile in their approach to 4.…”

Synthesis of Acyloxy‐Semicyclic Dienes Using an Enyne Metathesis/Ring Closing Metathesis Approach

“…This stereochemical control has been reported widely for Diels–Alder reactions of semicyclic dienes,2 and only a few examples have been observed where the endo–syn products3 have dominated. The utility of allylically substituted vinylcycloalkenes is demonstrated by their use in the synthesis of a wide range of angucycline antibiotics,4 including urdamycinone B,5 and towards other natural products 3a,6. These allylically substituted vinylcycloalkenes are readily available, although they have limitations due to lower reactivity.…”