title: Catalytic Carbonylative Spirolactonization of Hydroxycyclopropanols.
abstract: A palladium-catalyzed cascade carbonylative spirolactonization of hydroxycyclopropanols has been developed to efficiently synthesize oxaspirolactones common to many complex natural products of important therapeutic value. The mild reaction conditions, high atom economy, broad substrate scope, and scalability of this new method were highlighted in expedient total syntheses of the Turkish tobacco natural products α-levantanolide and α-levantenolide in two and four steps, respectively. The hydroxycyclopropanol substrates are readily available in one step via a Kulinkovich reaction of the corresponding lactones. Mechanistic studies utilizing high-resolution electrospray ionization mass spectrometry (ESI-MS) identified several key intermediates in the catalytic cycle, as well as those related to catalyst decomposition and competitive pathways.
authors.affiliation: Department of Chemistry and Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Dexter C
authors.initials: DC
authors.lastname: Davis
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Walker
authors.affiliation: Department of Chemistry, New York University , New York, New York 10003, United States.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Richard N
authors.initials: RN
authors.lastname: Zare
authors.affiliation: Department of Chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Waymouth
authors.affiliation: Department of Chemistry and Center for Cancer Research, Purdue University , West Lafayette, Indiana 47907, United States.
authors.forename: Mingji
authors.initials: M
authors.lastname: Dai