Chiral Lewis Acid-Catalyzed Asymmetric Multicomponent Michael Reaction through [1,2]-Phospha-Brook Rearrangement.

The multicomponent catalytic asymmetric Pudovik addition/[1,2]-phospha-Brook rearrangement/Michael reaction sequence of isatins, phosphites, and 4-oxobutenoates was realized. A series of oxindole derivatives containing two contiguous stereocenters was obtained in high yields and excellent stereoselectivities (up to >99% yield, >95:5 dr, >99% ee) using a chiral Lewis acid catalyst. A possible catalytic model is presented to illustrate the stereocontrol.

Catalytic Regio- and Enantioselective Protonation for the Synthesis of Chiral Allenes: Synergistic Effect of the Counterion and Water.

A highly enantioselective tandem Pudovik addition/[1,2]-phospha-Brook rearrangement of α-alkynylketoamides with diarylphosphine oxides was achieved with a N,N'-dioxide/ScIII complex as the catalyst. This protocol features broad substrate scope, high regio- and enantioselectivity, and good functional-group compatibility, providing a straightforward route to various trisubstituted allenes with a diarylphosphinate functionality in good yields with high enantioselectivities (up to 97 % yield, 96 % ee). Control experiments and theoretical calculations revealed that a synergistic effect of the counterion and water was critical for the regio- and enantioselective protonation after [1,2]-phospha-Brook rearrangement. The synthetic utility of this methodology was demonstrated by the conversion of products into complex bridged polycyclic architectures through intramolecular dearomatizing arene/allene cycloaddition.

Chiral Fe(ii) complex catalyzed enantioselective [1,3] O-to-C rearrangement of alkyl vinyl ethers and synthesis of chromanols and beyond.

A highly efficient enantioselective [1,3] O-to-C rearrangement of racemic vinyl ethers that operates under mild conditions was developed. This method with chiral ferrous complex catalyst provided an efficient access to a wide range of chromanols with high yields and excellent enantioselectivities. In addition, an important urological drug (R)-tolterodine and others were easily obtained after simple transformations.

Chiral N,N'-dioxide/Mg(OTf)2 complex-catalyzed asymmetric [2,3]-rearrangement of in situ generated ammonium salts.

Catalytic enantioselective [2,3]-rearrangements of in situ generated ammonium ylides from glycine pyrazoleamides and allyl bromides were achieved by employing a chiral N,N'-dioxide/MgII complex as the catalyst. This protocol provided a facile and efficient synthesis route to a series of anti-α-amino acid derivatives in good yields with high stereoselectivities. Moreover, a possible catalytic cycle was proposed to illustrate the reaction process and the origin of stereoselectivity.