10.1021/jo00288a047
The research focuses on the development of a new strategy for the construction of polyether antibiotic substructural units, such as spiroketals, tetrahydrofurans, and tetrahydropyrans. The strategy involves a tandem 1,3-dipolar cycloaddition and electrophilic cyclization sequence, which proceeds via the intermediacy of an isoxazoline. The method was found to be versatile and provided a unique exploitation of the control elements in dipolar cycloaddition and electrophilic cyclization chemistry. Key chemicals used in the process include various isoxazolines (e.g., la, lb, lc, Id, le, lg, lh), triphenylacetonitrile oxide, iodine, and different dienes such as 1,5-hexadiene, 1,7-octadiene, and 1,9-decadiene, among others. The research concluded that this approach could be a general and versatile route to the cyclic ether substructural units common to polyether antibiotics, with the ability to control stereoselectivity in the electrophilic cyclization step.