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- Title
Stereoselective synthesis of (−)‐cytoxazone and its unnatural congener (+)‐5‐epi‐cytoxazone.
- Authors
Miranda, Izabel Luzia; Santos, Pedro Henrique Costa; Kohlhoff, Markus; Purgato, Gislaine Aparecida; Diaz, Marisa Alves Nogueira; Diaz‐Muñoz, Gaspar
- Abstract
An interesting protocol for stereoselective synthesis of (−)‐cytoxazone and its unnatural stereoisomer (+)‐5‐epi‐cytoxazone from d‐4‐hydroxyphenylglycine in overall yields of 10% and 16%, respectively, is described. The stereoselective addition of cyanide to an N‐Boc protected aminoaldehyde (tert‐butyl ((R)‐1‐(4‐methoxyphenyl)‐2‐oxoethyl)carbamate) (5) constitutes the key step in this approach, producing a mixture of cyanohydrins 6a and b (1,2‐anti and 1,2‐syn tert‐butyl (2‐cyano‐2‐hydroxy‐1‐(4‐methoxyphenyl)ethyl)carbamate) in 89% yield, with reasonable stereoselectivity (1.0:1.8) in favor of the anti‐Felkin product (1,2‐syn). A one‐pot sequence of three successive steps from this mixture produced the oxazolidinone isomers 9a and b ((4R,5R)‐ and (4R,5S)‐4‐(4‐methoxyphenyl)‐2‐oxooxazolidine‐5‐carboxylate). Chromatographic column separation and reduction of the ester function of both precursors led to (−)‐cytoxazone and (+)‐5‐epi‐cytoxazone.
- Subjects
CYANOHYDRINS; ISOMERS; CYANIDES; STEREOSELECTIVE reactions; ESTERS; OXAZOLIDINONES
- Publication
Chirality, 2021, Vol 33, Issue 8, p479
- ISSN
0899-0042
- Publication type
Article
- DOI
10.1002/chir.23334