Kristina Deckers

Asymmetric Synthesis of Spiropyrazolones by Sequential Organo‐ and Silver Catalysis

A stereoselective one-pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia-ene reaction has been developed. Depending on the nitroalkene, the 5-exo-dig-cyclization could be achieved by silver-catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments.

Combining Silver Catalysis and Organocatalysis: A Sequential Michael Addition/Hydroalkoxylation One-Pot Approach to Annulated Coumarins

A highly stereoselective one-pot procedure for the synthesis of five-membered annulated hydroxycoumarins has been developed. By merging primary amine catalysis with silver catalysis, a series of functionalized coumarin derivatives were obtained in good yields (up to 91%) and good to excellent enantioselectivities (up to 99% ee) via a Michael addition/hydroalkoxylation reaction. Depending on the substituents on the enynone, the synthesis of annulated six-membered rings is also feasible.

Efficient Synthesis of Trifluoromethyl Amines through a Formal Umpolung Strategy from the Bench‐Stable Precursor (Me4N)SCF3

Abstract Reported herein is the one‐pot synthesis of trifluoromethylated amines at room temperature using the bench‐stable (Me4N)SCF3 reagent and AgF. The method is rapid, operationally simple and highly selective. It proceeds via a formal umpolung reaction of the SCF3 with the amine, giving quantitative formation of thiocarbamoyl fluoride intermediates within minutes that can readily be transformed to N‐CF3. The mildness and high functional group tolerance render the method highly attractive for the late‐stage introduction of trifluoromethyl groups on amines, as demonstrated herein for a range of pharmaceutically relevant drug molecules.

Direct Synthesis of Acyl Fluorides from Carboxylic Acids with the Bench-Stable Solid Reagent (Me4N)SCF3

A convenient, highly efficient, and selective transformation of aliphatic and aromatic carboxylic acids to acyl fluorides is reported. In contrast to established approaches that require toxic or volatile additives and base and reaction control (i.e., cooling, slow addition), this protocol allows for a straightforward access to various R-COF entities upon direct reaction with the bench-stable, solid reagent (Me4N)SCF3 at room temperature. The method is base- and additive-free, compatible with late-stage synthetic applications, high functional group tolerance, and facile target compound purification via filtration.

Asymmetric Squaramide Catalyzed Domino aza-Friedel-Crafts/N,O Acetalization Reactions Between 2-Naphthols and Pyrazolinone Ketimines

N-Boc ketimines derived from pyrazolin-5-ones were explored to develop an unprecedented domino aza-Friedel-Crafts/N,O-acetalization reaction with 2-naphthols. The novel method requires a catalyst loading of only 0.5 mol % of a bifunctional squaramide catalyst, is scalable to gram amounts, and provides a new series of furanonaphthopyrazolidinone derivatives bearing two vicinal tetra-substituted stereogenic centers in excellent yields (95-98 %) and stereoselectivity (>99:1 d.r. and 97-98 % ee). A different reactivity was observed in the case of 1-naphthols and other electron-rich phenols, which led to the aza-Friedel-Crafts adducts in 70-98 % yield and 47-98 % ee.