Catalytic Asymmetric Formal [3+2] Cycloaddition of 2-Isocyanatomalonate Esters and Unsaturated Imines: Synthesis of Highly Substituted Chiral γ‐Lactams

Unlike their isocyano and isothiocyanato analogues, isocyanato esters remain almost unexplored as formal 1,3-dipoles in asymmetric catalytic reactions. The first asymmetric formal [3+2] cycloaddition involving isocyanato esters and electrophilic alkenes is reported. Diisopropyl 2-isocyanatomalonate reacts with a,b-unsaturated N-(o-anisidyl) imines in the presence of aMg(OTf)2-BOX complex to give highly substituted chiral pyrrolidinones featuring a conjugate exocyclic double bond with excellent yields and enantiomeric excesses up to 99 %. Several transformations of the resulting heterocycles, including the synthesis of a pyroglutamic acid derivative, have been carried out

Copper-catalysed enantioselective Michael addition of malonic esters to β-trifluoromethyl-α,β-unsaturated imines

Copper triflate-BOX complexes catalyse the enantioselective conjugate addition of methyl malonate to β-trifluoromethyl-α,β-unsaturated imines to give the corresponding enamines bearing a trifluoromethylated stereogenic centre with good yields, and diastereo- and enantioselectivities. The usefulness of the method has been shown with the synthesis of optically active β-trifluoromethyl δ-amino esters and optically active trifluoromethylpiperidones

Mg/BOX complexes as efficient catalysts for the enantioselective Michael addition of malonates to β-trifluoromethyl-α,β-unsaturated ketones and their N-tosyl imines

Magnesium (II)-BOX complexes catalyze the enantioselective Michael addition of malonates to β-trifluoromethyl enones and their N-sulfonyl imines to give ketones or (E)-enamines bearing a trifluoromethylated stereogenic center, respectively, with good yields and high enantiomeric excesses. Magnesium complexes proved to be more active and stereoselective than zinc and copper analogues in these reactions