title: Synthesis of 12,12'-azo-13,13'-diepi-Ritterazine N.
abstract: A synthesis of the 12,12'-azo-analogue of ritterazine N from hecogenin is reported. Ring contraction of two 6/5 bicyclic ring systems, one trans-fused and another spiro, to 5/5 spiro ring systems is accomplished with excellent stereochemical control. Key transformations include an abnormal Baeyer-Villiger oxidation, a Norrish type I cleavage, an intramolecular dipolar [3 + 2] cycloaddition, and an intramolecular oxymecuration. Failing to uncover the β-OH ketone from the isoxazoline ring, we end up with a synthesis of a cyclic analogue of ritterazine N.
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Yong
authors.identifier: 0000-0002-7887-3050
authors.initials: Y
authors.lastname: Shi
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Jiang
authors.affiliation: CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences , 345 Lingling Road, Shanghai 200032, China.
authors.forename: Wei-Sheng
authors.initials: WS
authors.lastname: Tian