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- Title
Asymmetric Organocatalytic Synthesis of Fluorinated β‐Hydroxy Diazenes.
- Authors
Matador, Esteban; de Gracia Retamosa, María; Jiménez‐Sánchez, Antonio; Monge, David; Fernández, Rosario; Lassaletta, José M.
- Abstract
The nucleophilic addition of formaldehyde tert‐butyl hydrazone to fluoromethyl ketones provides a valuable tool for the synthesis of highly functionalized β‐hydroxy β‐tri‐ and difluoromethyl diazenes. Excellent reactivities and moderate to good enantioselectivities (up to 90 % ee) were achieved by H‐bonding activation exerted by tert‐Leucine derived H‐bonding (squaramide or thiourea) organocatalysts. Subsequent derivatizations in one‐pot fashion provide synthetically useful intermediates for target‐oriented synthesis: tri‐ and di‐fluoromethylated azoxy compounds, β‐amino alcohols, α‐hydroxy aldoximes and derivatives thereof. A formylation strategy:tert‐Leucine derived organocatalysts promote the enantioselective 1,2‐addition of FTBH to fluorinated ketones to afford quaternary β‐hydroxy β‐fluoromethyl diazenes in excellent yields and moderate‐to‐good enantioselectivities. Subsequent high‐yielding and racemization‐free transformations provide an expedient entry to enantioenriched azoxy compounds, aldehydes and derivatives thereof.
- Subjects
DIAZENES; FORMYLATION; HYDROXY acids; CHEMICAL synthesis; CHEMICAL reactions
- Publication
European Journal of Organic Chemistry, 2019, Vol 2019, Issue 1, p130
- ISSN
1434-193X
- Publication type
Article
- DOI
10.1002/ejoc.201801477