Reductive Deamination by Benzyne for Deoxy Sugar Synthesis Through a Domino Reaction. Issue 3 (5th May 2017)

• Record Type: Journal Article
• Authors: Hwu, Jih Ru; Chandrasekhar, D. Balaji; Hwang, Kuo Chu; Lin, Chun‐Cheng; Horng, Jia‐Cherng; Shieh, Fa‐Kuen
• Is Part Of: ChemistryOpen. Volume 6:Issue 3(2017)
• Page Start: 331
• Page End: 335
• Publication Date: 2017-05-05
• Subjects: benzyne -- deamination -- deoxy sugars -- domino reactions -- reduction; Chemistry -- Periodicals; 540; 540.5
• DOI: 10.1002/open.201700050
• Languages: English
• ISSNs: 2191-1363

Abstract

Abstract: Benzyne was developed as a reducing agent in the key step of converting amino sugars and ketoses into deoxy sugars, which occur widely in natural products. Many deoxy sugars exhibit antibiotic and anticancer activities, and furthermore, they play essential biological roles. By treatment with CS2 and then Ac2 O, amino sugars and ketoses were converted into the corresponding 1, 3‐thiazolidine‐2‐thiones. In the key step, these intermediates were treated with 2‐trimethylsilylphenyl triflate (2.0 equiv.) and CsF (3.0 equiv.) in MeCN at 25 °C to produce acyclic enol acetates in 60–63 % yields. Saponification of the enol acetates with NaOMe/MeOH followed by intramolecular cyclization afforded the target 2‐deoxy sugars. The key step of the reductive deamination involved a domino 1, 2‐elimination/[3+2]‐cycloaddition/retro [3+2]‐ring‐opening sequence. The generality of this new method was proven by the use of various substrates, including pentoses, hexoses, monosaccharides, disaccharides, aldoses, and ketoses. Abstract : Sweet talk : As an oxidized form of benzene, benzyne can act as a reducing agent to remove the nitrogen and sulfur atoms from 1, 3‐thiazolidine‐2‐thiones. This "reagent" is applied in the synthesis of deoxy sugars from amino sugars and ketoses.