Catalytic Carbonylative Spirolactonization of Hydroxycyclopropanols.
Journal of the American Chemical Society
2016; 138 (33): 10693-10699
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.
View details for DOI 10.1021/jacs.6b06573
View details for PubMedID 27459274
- Catalytic Role of Multinuclear Palladium-Oxygen Intermediates in Aerobic Oxidation Followed by Hydrogen Peroxide Disproportionation JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2015; 137 (42): 13632-13646
- Retaining the Activity of Enzymes and Fluorophores Attached to Graphene Oxide CHEMISTRY OF MATERIALS 2015; 27 (12): 4499-4504
Regioselective Asao-Yamamoto Benzannulations of Diaryl Acetylenes
2014; 16 (22): 5926-5929
Asao-Yamamoto benzannulations transform diarylalkynes into 2,3-diarylnaphthalenes, and regioselective variants of this reaction are of interest for synthesizing substituted polycyclic aromatic systems. It is shown that regioselective cycloadditions occur when one alkyne carbon preferentially stabilizes developing positive charge. Simple calculations of the relative energies of carbocations localized at each alkyne carbon of a substrate predict the regioselectivity, which is not eroded by bulky substituents, including 2,6-disubstituted aryl groups.
View details for DOI 10.1021/ol502938y
View details for Web of Science ID 000345470000026
View details for PubMedID 25383421