title: Synthesis of the spirastrellolide A, B/C spiroketal: enabling solutions for problematic Au(I)-catalyzed spiroketalizations.
abstract: A synthesis of the spirastrellolide A, B/C-ring monounsaturated spiroketal is reported. The key step relies on a Au-catalyzed spiroketalization of a propargyl triol employing an acetonide as a regioselectivity regulator. Through observation and analysis, a set of conditions has been developed that facilitates the use of a mixture of diastereomeric substrates, obviating the need to control the stereochemistry of the propargyl stereocenter and enabling a convenient retrosynthetic disconnection. The key reaction proceeds in 80% yield in 1 min at ambient temperature with the Me3PAuCl/AgOTf catalyst system. These conditions should be widely applicable for new synthetic endeavors as they appear to overcome all issues with the Au-catalyzed spiroketalization.
authors.affiliation: Department of Chemistry, Center for Heterocyclic Compounds, University of Florida, Gainesville, Florida 32611, United States.
authors.forename: Barry B
authors.initials: BB
authors.lastname: Butler
authors.affiliation: Department of Chemistry, Center for Heterocyclic Compounds, University of Florida, Gainesville, Florida 32611, United States.
authors.forename: Jagadeesh Nagendra
authors.initials: JN
authors.lastname: Manda
authors.affiliation: Department of Chemistry, Center for Heterocyclic Compounds, University of Florida, Gainesville, Florida 32611, United States.
authors.forename: Aaron
authors.initials: A
authors.lastname: Aponick
mesh_terms: D002384:Catalysis; D006046:Gold / Q000737:chemistry*; D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D012996:Solutions; D013141:Spiro Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D018942:Macrolides; D012996:Solutions; D013141:Spiro Compounds; C475125:spirastrellolide A; C519027:spirastrellolide B; C526566:spirastrellolide C; D006046:Gold