title: Atom-economic and stereoselective syntheses of the ring a and B subunits of the bryostatins.
abstract: This article describes chemoselective and atom-economic methods for the stereoselective assembly of the ring A and B subunits of bryostatins. A Ru-catalyzed tandem alkene-alkyne coupling/Michael addition reaction was developed and applied to the synthesis of bryostatin ring B. We explored an acetylide-mediated epoxide-opening/6-exo-dig cyclization route to access the bryostatin ring A, although ring A was eventually furnished through an acid-catalyzed tandem transketalization/ketalization sequence. In addition, a dinuclear zinc-catalyzed methyl vinyl ketone (MVK) aldol strategy was evaluated for the construction of the polyacetate moiety. Utilization of these methods ultimately led to the rapid assembly of the northern bryostatin fragment containing both the ring A and B subunits.
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA. bmtrost@stanford.edu
authors.forename: Barry M
authors.initials: BM
authors.lastname: Trost
authors.forename: Hanbiao
authors.initials: H
authors.lastname: Yang
authors.forename: Cheyenne S
authors.initials: CS
authors.lastname: Brindle
authors.forename: Guangbin
authors.initials: G
authors.lastname: Dong
mesh_terms: D054713:Bryostatins / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D054713:Bryostatins; D018942:Macrolides; D010165:Palladium