Efficient Asymmetric Synthesis of Chiral Monomer of Epoxyquinols and (-)-Phyllostine

Synthesis of (+)‐Epoxydon, (–)‐Phyllostine, (–)‐RKTS 33, and (–)‐Parasitenone Featuring Selective Sulfonylation and Oxirane Ring Closure of Aldol Cyclization Products

“…it would be reasonable that preferential access of NaBH(OAc) 3 to the carbonyl group from the side opposite to the oxirane ring gives cis-epoxy alcohol intermediate. On the other hand, following Ryu's procedure, [21] coordination-controlled reduction of (-)-phyllostine with DIBAL-H exhibited inverse stereoselectivity to generate (-)-RKTS 33 with 68 % yield through the complexation of the aluminium with the epoxide oxygen and primary hydroxyl group.…”

Total Synthsis of (+)-Ambuic Acid: α-Bromination with 1,2-Dibromotetrachloroethane

“…The Mehta group developed an approach for the total synthesis of ambuic acid in racemic form using the Diels–Alder adducts of cyclopentadiene and 2-allyl- p -benzoquinone . In recent years, our group has been interested in developing a general approach for the synthesis of natural cyclohexenone epoxide products . Herein, we report first efficient method for the total synthesis of (+)-ambuic acid 1 , which requires the easily available Diels–Alder adduct 6 , prepared from the catalytic enantioselective Diels–Alder reaction with a chiral oxazaborolidinium ion …”

“…Optically pure Diels–Alder adduct 6 was obtained through the highly enantioseletive Diels–Alder reaction of cyclopentadiene and 2-iodo-1,4-quinone monoketal 7 , as we recently described (Scheme ). , The reaction was carried out at −78 °C by stirring 2-iodo-1,4-quinone monoketal 7 and cyclopentadiene in the presence of chiral ( R )-oxazaborolidium catalyst 8 (20 mol %) in dichloromethane under nitrogen.…”

Enantioselective Synthesis of Natural Epoxyquinoids

“…Using an ent-oxazaborolidium catalyst, Ryu obtained ent-263, which was used in a similar route to prepare natural phyllostine (27) ECH (8) was also synthesized by Ryu and co-workers in the cited article [141]. Using ent-phyllostine (scheme 44) as a precursor, under regioselective and stereoselective reduction conditions (Kiyooka's protocol), the authors obtained alcohol RKTS-33 (9).…”