Weihui Zhong

Asymmetric [3+2]-Cycloaddition of Morita–Baylis–Hillman Carbonates with Maleimides Catalyzed by Chiral Ferrocenylphosphines

Abstract New chiral ferrocenylphosphines LB1–LB9 were designed and prepared through simple synthetic approaches. These air-stable ferrocenylphosphines were applied to promote asymmetric [3+2]-cycloaddition of Morita–Baylis–Hillman carbonates with maleimides, among which LB7 was shown to have good catalytic activity to afford the corresponding multifunctional cyclopentenes in up to 59% yield and up to 53% ee under mild reaction conditions. A plausible reaction mechanism was proposed. GRAPHICAL ABSTRACT

Efficient Synthesis of a New Type of Baylis–Hillman Adducts and Their Stereoselective Bromination

A new type of Baylis–Hillman adducts derived from chlorovinyl aldehydes were prepared via Vilsmeier reaction of ketones with a bis(trichloromethyl) carbonate (BTC)/DMF system to construct chlorovinyl aldehydes, followed by sonochemical Baylis–Hillman reaction under solvent-free conditions. The stereoselective bromination of these new compounds with a Br2-Ph3P system has been achieved efficiently with good to excellent yields under mild conditions.

Dramatically Accelerated Addition Under Solvent-Free Conditions: An Efficient Synthesis of (E)-1,2,4-Triazole-Substituted Alkenes from Baylis–Hillman Acetates

Abstract The addition of 1,2,4-triazole to Baylis–Hillman acetates mediated by Et3N was dramatically accelerated under solvent-free conditions to afford (E)-1,2,4-triazole-substituted alkenes 3 with excellent yields.

Metal-Oxidant-Free Cobalt-Catalyzed C(sp2)–H Carbonylation of ortho-Arylanilines: An Approach toward Free (NH)-Phenanthridinones

A traceless directing group assisted Co-catalyzed C(sp2)-H carbonylation of ortho-arylanilines for the synthesis of free ( NH)-phenanthridinones in metal-based-oxidant-free fashion was accomplished. This protocol employs diisopropyl azodicarboxylate as the CO source and oxygen as the sole oxidant, and provides good yields with various functional tolerance. The methodology has been applied for the total synthesis of PARP inhibitor PJ-34. Furthermore, the kinetic isotopic effect experiments reveal the C-H bond cleavage probably occurred in the rate-determining step.

Efficient and mild swern oxidation using a new sulfoxide and bis(trichloromethyl)carbonate

ABSTRACT A new type of sulfoxide, 4-(2-(2-(methylsulfinyl) ethyl)-4-nitrophenyl)- morpholine (I), was designed and prepared in good yield. Upon the combination of I and bis(trichloromethyl)carbonate, the Swern oxidation of primary and secondary alcohols was significantly promoted under mild conditions, which afforded the corresponding aldehydes or ketones in good yields. It is noteworthy that the reoxidation of the isolated by-product sulfide V could be further recycled in Swern oxidation. GRAPHICAL ABSTRACT

Catalyst-free three-component approach to efficient synthesis of chromeno[4,3-b]pyrrol-4(1H)-one derivatives

ABSTRACT A mild, efficient, and environmentally benign one-pot synthesis of functionalized chromeno[4,3-b]pyrrol-4(1H)-ones by a three-component domino reaction of 4-aminocoumarins, arylglyoxal monohydrates, and 1,3-dicarbonyl compounds in refluxing ethanol without the use of catalyst is reported. The present protocol features operational simplicity, short reaction time, good yields, and the absence of aqueous workup procedure and chromatographic separation. GRAPHICAL ABSTRACT

B(C6F5)3-Catalyzed Asymmetric Reductive Amination of Ketones with Ammonia Borane

The first example of metal-free B(C6F5)3-catalyzed asymmetric reduction amination of ketones with chiral α-methylbenzylamine (α-MBA) using ammonia borane as the reductant is reported. This one-pot method has a broad substrate scope and provides various chiral amines in 81-95% yield with 80-99% de. This protocol was further applied in the total synthesis of cinacalcet.

Development of Ferrocene-Based Diamine-Phosphine-Sulfonamide Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones

A series of air-stable, easily accessible tridentate ferrocene-based diamine-phosphine sulfonamide (f-diaphos) ligands were successfully developed for iridium-catalyzed asymmetric hydrogenation of ketones. The f-diaphos ligands exhibited excellent enantioselectivity and superb reactivity in Ir-catalyzed asymmetric hydrogenation of ketones (for arylalkyl ketones, ( S)-selectivity, up to 99.4% ee, and 100 000 TON; for diaryl ketones, ( R)-selectivity, up to 98.2% ee, and 10 000 TON). This protocol could be easily conducted on gram scale, thereby providing a chance to various drugs.