Zhen-Jiang Xu

Chiral Brønsted Acid-Catalyzed Enantioselective α-Hydroxylation of β-Dicarbonyl Compounds

A novel, facile, and highly enantioselective Brønsted acid-catalyzed alpha-hydroxylation of beta-dicarbonyl compounds with up to 99:1 er using nitroso compounds as the oxygen source has been developed. The results disclosed herein considerably extend the substrate scope for the alpha-aminoxylation, allowing expeditious, straightforward, and efficient access to valuable alpha-hydroxy-beta-dicarbonyl compounds with the highest levels of enantiocontrol.

Ruthenium-catalyzed one-pot carbenoid N-H insertion reactions and diastereoselective synthesis of prolines.

Aryl- and aliphatic-substituted 3-hydroxyprolines and various other amino esters are conveniently prepared by [RuCl2(p-cymene)]2-catalyzed one-pot intramolecular and intermolecular carbenoid N-H insertion reactions, respectively, and the prolines are formed with high diastereoselectivities. The catalytic reactions are tolerant toward air/moisture, and the product yields are insensitive to the organic solvents used.

Dirhodium Carboxylates Catalyzed Enantioselective Coupling Reactions of α-Diazophosphonates, Anilines, and Electron-Deficient Aldehydes

Chiral dirhodium carboxylate complexes ([Rh(2)(S-PTAD)(4)] or [Rh(2)(S-PTTL)(4)]) efficiently catalyze asymmetric three-component coupling reactions of α-diazophosphonates, anilines, and electron-deficient aldehydes to give α-amino-β-hydroxyphosphonates. The high level of enantiocontrol provides evidence for the intermediacy of metal-bound ammonium ylide in the product-forming step.

Highly Efficient Asymmetric Trans-Selective Aziridination of Diazoacetamides and N-Boc-imines Catalyzed by Chiral Brønsted Acids

A clean and fast (10 min) aziridination of diazoacetamides with N-Boc-imines, as well as N-Cbz-imines, catalyzed by chiral phosphoric acid (R)-5g in DCM at room temperature was developed. The excellent yields (89-97%), diastereoselectivities (trans/cis > 50:1), chemoselectivities (3:4 = >95:5), and enantioselectivities (88-98% ee) were achieved in the reaction.

Highly enantioselective intermolecular carbene insertion to C–H and Si–H bonds catalyzed by a chiral iridium(III) complex of a D4-symmetric Halterman porphyrin ligand

The chiral iridium porphyrin [Ir((-)-D(4)-Por*)(Me)(EtOH)] displays excellent reactivity and stereoselectivity towards carbene insertion to C-H and Si-H bonds, affording corresponding products in high yields (up to 96%) and high enantioselectivities (up to 98% ee).

Selective oxidation of terminal aryl and aliphatic alkenes to aldehydes catalyzed by iron(III) porphyrins with triflate as a counter anion.

[Fe(Por)CF(3)SO(3)] (Por = porphyrin dianion) can efficiently catalyze selective oxidation of terminal aryl alkenes and aliphatic alkenes to aldehydes in good to high yields under mild conditions.

Iron Porphyrin Catalyzed Insertion Reaction of N-Tosylhydrazone-Derived Carbenes into X–H (X = Si, Sn, Ge) Bonds

An efficient Fe(TPP)Cl catalyzed insertion reaction of in situ generated benzylic carbenes from N-tosylhydrazones into X-H (X = Si, Sn, Ge) was developed. Silanes bearing tertiary, secondary, and primary (3°, 2°, and 1°) Si-H bonds all reacted well to afford insertion products in moderate to high yields (up to 97%), and the reaction time could be significantly shortened to 1 h under microwave irradiation. A programmable stepwise double insertion strategy was developed for the synthesis of unsymmetrical tetrasubstituted silanes.