Synthesis of (+)-siphonarienone: Asymmetric alkylation using a chiral benzopyrano-isoxazolidine auxiliary

Article abstract of DOI:10.1016/0040-4039(95)02353-4

Asymmetric alkylation of the potassium enolates derived from N-propionyl benzopyrano[4,3-c]-isoxazolidine derivatives with chiral alkyl triflates proceeded smoothly with high diastereoselectivity. The stereochemistry of the newly formed stereogenic center was fully controlled by the facial selectivity of the enolate according to the rule of double asymmetric synthesis. The application of this methodology led to the first synthesis of (+)-siphonarienone, a marine polypropionate natural product.