An efficient asymmetric aerobic oxidation of tetrahydroisoquinolines with terminal alkynes was realized under mild reaction conditions using O 2 as the sole oxidant. A chiral N,N′-dioxide/zinc(II)/iron(II) bimetallic cooperative catalytic system proves to be efficient for the formation of various α-alkynyl substituted tetrahydroisoquinolines in good to excellent yields and enantioselectivities. A primary mechanistic study supports an enantioselective electrophilic addition of zinc acetylide to the iminium intermediates, formed through a molecular O 2 -involved oxidative process.

A highly enantioselective conjugate addition/ Dieckmann cyclization of 3-carboxymethyl substituted oxindoles with electron-deficient internal alkynes was achieved under the catalysis of a chiral guanidine catalyst and NaH. This protocol provides access to a wide range of synthetically useful optically active spirocyclopentenone oxindoles and their derivatives under mild reaction conditions.

No abstract

A highly regio-, diastereo-, and enantioselective Diels−Alder reaction of β,γ-unsaturated α-ketoesters with (E)-1phenyl dienes has been accomplished by using a stable and easily available chiral N,N′-dioxide/zinc(II) complex as catalyst. Only one isomer of the corresponding cyclohexenes with three chiral centers was obtained in good to excellent yields with excellent ee values under mild reaction conditions. The configurations of the product and chiral N,N′-dioxide/zinc(II) catalyst were identified by X-ray diffraction analysis. In addition, a possible catalytic model was proposed to explain the origin of the asymmetric induction.

An asymmetric intramolecular Alder-ene reaction has been developed to synthesize diverse 3,4-disubstituted chroman, tetrahydroquinoline, piperidine and thiochroman derivatives.