Inter- and intramolecular reactions of 1-deoxy-1-thio-1,6-anhydrosugars with α-diazoesters: synthesis of the tagetitoxin core by photochemical ylide rearrangement

• Published in: Organic & biomolecular chemistry 2012-11, Vol.10 (43), p.8616-8627
• Main Authors: Price Mortimer, Anne J, Plet, Julien R H, Obasanjo, Oluwafunsho A, Kaltsoyannis, Nikolas, Porter, Michael J
• Format: Article
• Language: English
• Subjects: Azo Compounds - chemistry; Dicarboxylic Acids - chemical synthesis; Dicarboxylic Acids - chemistry; Esters - chemistry; Molecular Structure; Oligosaccharides - chemistry; Organophosphorus Compounds - chemical synthesis; Organophosphorus Compounds - chemistry; Photochemical Processes; Quantum Theory; Sulfhydryl Compounds - chemistry
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c2ob26308d

The one-carbon ring expansion of 1-deoxy-1-thio-1,6-anhydrosugars, mediated by metal carbenes and proceeding through the intermediacy of sulfur ylides, has been proposed as a route for the synthesis of the tagetitoxin skeleton. Intermolecular reactions of such thioanhydrosugars with diazoesters afford a range of undesired products derived from the initially formed ylide, whereas use of an intramolecular process generates stable ylides which can be converted to the tagetitoxin skeleton by photo-Stevens rearrangement. Computational studies using density functional theory indicate that the photochemical rearrangement likely proceeds through a homolysis-recombination pathway.