Oxidation of ylide precursors to vicinal tricarbonyls. Applications in vincamine alkaloid synthesis.

Exploration of Cascade Cyclizations Terminated by Tandem Aromatic Substitution: Total Synthesis of (+)-Schweinfurthin A

“…30 Intermediate 67 was oxidized with TPAP/NMO64 to provide the new ketone 68 . Condensation of ketone 68 with benzaldehyde provided enone 69 , which was to be utilized as a latent carbonyl group 65, 66. Reduction proceeded smoothly under Luche conditions67 to afford alcohol 70 in excellent yield.…”

The Chemistry of Vicinal Polycarbonyl Compounds

“…One of the advantages of this procedure is that it leads to large crystals of 4a which can be manipulated more readily since much less surface is exposed. The preparation of diethyl diketosuccinate (112) from the disodium salt of dihydroxytartaric acid by esterification and distillation has been described in a paper by Boger et al 103 Hydrates have been converted to bis-trimethylsilyloxy derivatives (113) which afforded polycarbonyls on heating. 104 Attempts to obtain rhodizonic acid (114) from its hydrate by this method were not successful.…”

Total Synthesis of Indole Alkaloid (±)-Subincanadine F via SmI2-Mediated Ring Opening and Bridge-Forming Mannich Reaction

“…As shown in Scheme , the synthesis commenced from 1-( para -methoxybenzyl)tryptamine ( 4 ), a known intermediate obtainable in one step from commercially available tryptamine. A reaction of 4 with α,β-diketoester 5 (140 mol %) in acetonitrile at room temperature for 8 h afforded in a 75% yield the tetracyclic ketoester 6 as a yellow solid. The generation of 6 presumably results from the initial N-alkylation and iminium ion formation followed by Pictet−Spengler-type cyclization as depicted in Scheme .…”