Direct lactonization of α-amino γ,δ-unsaturated carboxylic acid esters via olefin activation: stereo- and regioselective production of homoserine lactone scaffolds having contiguous stereocenters

Dinuclear zinc-catalyzed asymmetric [3 + 2] cyclization reaction for direct assembly of chiral α-amino-γ-butyrolactones bearing three stereocenters

A highly atom-economic and novel enantioselective [3 + 2] cyclization reaction for the construction of optical α-amino-γ-butyrolactones possessing three stereocenters.

From racemic precursors to fully stereocontrolled products: one-pot synthesis of chiral α-amino lactones and lactams

Substituted racemic lactols or cyclic hemiaminals were directly used as nucleophiles in enamine-based asymmetric amination reactions to access enantioenriched α-amino lactones or lactams via a one-pot sequence. The desired products, which are very important building blocks in organic synthesis but difficult to be prepared in the optically enriched form, could be afforded with two stereogenic centers in high yields with excellent enantioselectivities. Moreover, starting from the racemic precursors and catalyzed by the enantiomeric pair of the catalyst, all possible stereoisomeric products were discretely provided only after simple column chromatography. Additionally, this protocol provides facile access to several novel bicyclic carbamates, and such drug-like heterocyclic compounds should be potentially useful in medicinal chemistry.

Synthesis of α-Benzyloxyamino-γ-butyrolactones via a Polar Radical Crossover Cycloaddition Reaction

A direct catalytic synthesis of substituted α-benzyloxyamino-γ-butyrolactones is reported, starting from simple oxime acids and alkenes. The substituted O-benzyloxime acid starting materials are cyclized with oxidizable alkenes, via Polar Radical Crossover Cycloaddition (PRCC) reactions. The catalytic reaction is carried out using the Fukuzumi acridinium photooxidant and substoichiometric amounts of a redox-active cocatalyst. The utility of this method has been demonstrated through the use of 3 oxime acids and 19 oxidizable olefins.