AI Article Synopsis
- Researchers developed a method to create chiral β-fluoroamines from α-fluoro cyclic ketones and α-amidosulfones using a chiral catalyst and KF as the base, achieving high enantioselectivity even at elevated temperatures.
- The process is notable for being transition-metal-free, straightforward, and allowing the direct use of stable precursors, which simplifies the synthesis of sensitive imines.
- This method provides excellent stereoselectivity, yielding products with up to 99% enantiomeric excess and scalability for synthesizing biologically relevant compounds, including those with C-Cl and C-Br centers.
Article Abstract
A direct route to chiral β-fluoroamines with tetrasubstituted C-F centers through the organocatalytic Mannich reaction of α-fluoro cyclic ketones and α-amidosulfones by using a chiral oligoethylene glycol as a cation-binding catalyst and KF as a base is reported. For most substrates, nearly perfect enantioselectivities were achieved even at very high temperatures (>80 °C). The salient features of this process include a) a transition-metal-free and operationally simple procedure, b) direct use of α-amidosulfones as bench-stable precursors of sensitive imines, c) direct enolization of racemic α-fluoro cyclic ketones, and d) excellent stereoselectivity up to 99 % enantiomeric excess and >20:1 diastereoselectivity (anti/syn). Thus, this protocol is easily scalable and provides a new approach for the synthesis of biologically relevant products with tetrasubstituted C-F centers. Furthermore, this protocol was also successfully extended to generate C-Cl and C-Br quaternary stereogenic centers.
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| http://dx.doi.org/10.1002/chem.201605637 | DOI Listing |
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