183322-78-3Relevant academic research and scientific papers
Total syntheses of ent-heliespirones A and C
Bai, Wen-Ju,Green, Jason C.,Pettus, Thomas R. R.
experimental part, p. 379 - 387 (2012/02/15)
Stereodivergent total syntheses of ent-heliespirone A and C were both completed in 11 vessels and ～24% combined overall yield (A + C). These syntheses employed an identical inverse demand Diels-Alder reaction between a surrogate for an extendedly conjugated γ-δ unsaturated ortho-quinone methide and l-lactic-acid-derived exocyclic enol ether. Novel reactions of special note include a diastereoselective reduction of a chroman spiroketal by combination of borontrifluoride etherate and triethyl silane, along with oxidative rupture of a chroman etherial ring into the corresponding p-quinone by argentic oxide (AgO). In addition, an unusual intramolecular etherification of a 3° alcohol caused by cerium ammonium nitrate was observed.
