Decarboxylation data method

Physical Data bp 70 °C/0.02 mmHg [a]g = +434° (c 1, CHCI3). Solubility sol all common nonprotic organic solvents. Preparative Methods the acetal from serine methyl ester and pivaladehyde is IV-methoxycarbonylated and saponified to give the cw-half ester (2) (61% yield). Oxidative decarboxylation by electrolysis in AcOH (1 3 by weight) in the presence of 5% EtaN affords (3) (87%), which upon heating with NH4Br in toluene yields the title oxazoline (1) (75% after distillation in vacuo) (eq 1). ... 

Next, alcohol 35 was transformed into 36 by reductive dehydroxylation via the nonisolated intermediate xanthate. Hydrolysis of the ester group in 35 to form 30 was followed by decarboxylation to generate 37 by using an improved Barton s method employed with HOTT (5-(l-oxido-2-pyr-idinyl) 1,1,3,3-tetramethylthiouronium hexafluorophos-phate) [35]. Treatment of 37 with TBAF furnished alcohol, which was converted into the proposed structure of paesslerin A by using scandium-catalyzed acetylation. Unfortunately, comparisons of the H- and C-NMR data of the synthetic compound with those reported for the natural product revealed that the substances are not identical. The 2D-NMR data for synthetic 29 are fiiUy consistent with the structure of the target. The result clearly demonstrates that a revision of the structure of natural paesslerin A is required (Scheme 4.17). 

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