title: Total synthesis of epoxyquinols A, B, and C and epoxytwinol A and the reactivity of a 2H-pyran derivative as the diene component in the Diels-Alder reaction.
abstract: Full details of two versions of the total synthesis of epoxyquinols A, B, and C and epoxytwinol A (RKB-3564D) are described. In the first-generation synthesis, the HfCl(4)-mediated diastereoselective Diels-Alder reaction of furan with Corey's chiral auxiliary has been developed. In the second-generation synthesis, a chromatography-free preparation of an iodolactone, by using acryloyl chloride as the dienophile in the Diels-Alder reaction of furan, and the lipase-mediated kinetic resolution of a cyclohexenol derivative have been developed. This second-generation synthesis is suitable for large-scale preparation. A biomimetic cascade reaction involving oxidation, 6pi-electrocyclization, and then Diels-Alder dimerization is the key reaction in the formation of the complex heptacyclic structure of epoxyquinols A, B, and C. Epoxytwinol A is synthesized by the cascade reaction composed of oxidation, 6pi-electrocyclization, and formal [4 + 4] cycloaddition reactions. A 2H-pyran, generated by oxidation/6pi-electrocyclization, acts as a good diene, reacting with several dienophiles to afford polycyclic compounds in one step. An azapentacyclic compound is synthesized by a similar cascade reaction composed of the four successive steps: oxidation, imine formation, 6pi-azaelectrocyclization, and Diels-Alder dimerization.
authors.affiliation: Department of Industrial Chemistry, Faculty of Engineering, Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Shoji
authors.forename: Hiroki
authors.initials: H
authors.lastname: Imai
authors.forename: Makoto
authors.initials: M
authors.lastname: Mukaida
authors.forename: Ken
authors.initials: K
authors.lastname: Sakai
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kakeya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Osada
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D001203:Ascomycota / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D004852:Epoxy Compounds / Q000138:chemical synthesis*; D006873:Hydroquinones / Q000138:chemical synthesis*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011714:Pyrans / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D004852:Epoxy Compounds; D006873:Hydroquinones; D011714:Pyrans; C455959:epoxyquinol A; C469247:epoxyquinol B; C496190:epoxyquinol C; C496191:epoxytwinol A