Catalytic Enantioselective C–C Bond-Forming Reactions of Deconjugated Butyrolactams: Michael Addition to α,β-Unsaturated Aldehydes and Ketones

Catalytic asymmetric de novo construction of 4-pyrrolin-2-ones via intermolecular formal [3+2] cycloaddition of azoalkenes with azlactones

The chiral phosphoric acid-catalyzed asymmetric intermolecular formal [3+2] cycloaddition of azoalkenes with azlactones has been established. This convergent protocol leads to a facile and enantioselective de novo construction of a wide range of fully substituted 4-pyrrolin-2-ones bearing a fully substituted carbon atom in good yields and with excellent enantioselectivities (26 examples, 72-95% yields and 87-99% ee).

Enantioselective direct vinylogous Michael addition for constructing enantioenriched γ,γ-dialkyl substituted butyrolactams and octahydroindoles

A nickel(II)-catalyzed asymmetric direct vinylogous Michael addition of γ-alkyl monosubstituted α,β-unsaturated butyrolactams to α,β-unsaturated carbonyl compounds has been disclosed, affording γ,γ-dialkyl substituted butyrolactams in good yields and satisfactory enantioselectivities. A tandem catalytic asymmetric vinylogous Michael addition/intramolecular Michael addition has also been developed based on this reaction, which enabled the construction of enantioenriched octahydroindoles with three consecutive stereogenic carbon centers.

Chiral tertiary amine-squaramide catalyzed highly enantioselective Michael addition of cyclic diketones to β,γ-unsaturated α-keto Esters

Abstract:

A novel tertiary amine squaramide has successfully developed and applied to catalyze the asymmetric Michael addition between cyclic diketones and β,γ-unsaturated α-ketoesters. The catalyst system performed well with a low catalyst loading of 1 mol% under mild reaction conditions. A series of synthetically and pharmaceutically useful chiral bicyclic compounds were obtained with both high yields (up to 97%) and excellent enantioselectivities (up to 97% ee).

Iridium-Catalyzed Asymmetric Allylic Alkylation of Deconjugated Butyrolactams

Compared with the ever-growing list of nonprochiral nucleophiles in Ir-catalyzed asymmetric allylic substitution reactions, prochiral nucleophiles are less studied. We present a new prochiral nucleophile, namely, deconjugated butyrolactam, for Ir-catalyzed asymmetric allylic alkylation (AAA). This reaction provides access to α-allyl deconjugated butyrolactams with a moderate to good dr and an excellent er. This is the first AAA reaction of deconjugated butyrolactams. Allyl transposition through Cope rearrangement appears to proceed stereospecifically to form γ-allyl conjugated butyrolactams.

The reticent tautomer: exploiting the interesting multisite and multitype reactivity of 4-pyrrolin-2-ones

Multisite and multitype reactivities of the highly versatile and valuable synthetic building block 4-pyrrolin-2-one are covered in this review.