Total synthesis of (+)-UCS1025A based on a sequential Michael-retro Michael strategy featuring one-pot six-step cascade reaction. Issue 8 (21st February 2018)

• Record Type: Journal Article
• Authors: Sano, Ryota; Kosuge, Ryo; Tsubogo, Tetsu; Uchiro, Hiromi
• Is Part Of: Tetrahedron letters. Volume 59:Issue 8(2018)
• Page Start: 704
• Page End: 707
• Publication Date: 2018-02-21
• Subjects: UCS1025A -- Total synthesis -- Pyrrolizidinone -- Cascade reaction -- Michael-retro Michael; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tetlet.2017.12.025
• Languages: English
• ISSNs: 0040-4039

Abstract

Graphical abstract: Highlights: The asymmetric total synthesis of UCS1025A is accomplished. A novel sequential Michael- retro Michael strategy was successfully developed. An efficient one-pot transformation into tricyclic pyrrolizidinone was achieved. The high-yielding one-pot transformation consists of six step reactions. Abstract: The asymmetric total synthesis of UCS1025A is accomplished by establishing a novel and efficient method for the construction of a tricyclic pyrrolizidinone skeleton based on a sequential Michael- retro Michael strategy. The key step is a one-pot six-step cascade reaction including oxidation of a primary alcohol to the corresponding carboxylic acid, a retro thio-Michael reaction, and an intramolecular oxy-Michael reaction. This newly-developed synthetic strategy inspired by "masked" electrophilic character of tricyclic pyrrolizidinone is efficient and high-yielding compared to that developed in previously-reported total syntheses.