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

Keywords:

• Asymmetric [3+2]-cycloaddition reaction
• catalyst
• chiral ferrocenylphosphines
• cyclopentene

Notes

^a Unless otherwise specified, the reactions were performed with 1a (0.5 mmol) and 2a (1 mmol) and catalyst (0.05 mmol) in toluene (1.0 mL) at room temperature.

^b Isolated yield.

^c The ee value was determined by HPLC analysis using a chiral column.

^a Unless otherwise specified, the reactions were performed with 1a (0.5 mmol), 2a (1 mmol), and LB7 (0.05 mmol) in toluene (1.0 mL) at room temperature.

^b Isolated yield.

^c The ee value was determined by HPLC analysis using a chiral column.

^a Unless otherwise specified, the reactions were performed with 1a (0.5 mmol), 2a (1 mmol), and LB7 (0.05 mmol) in toluene (1.0 mL) at room temperature.

^b Isolated yield.

^c The ee value was determined by HPLC analysis using a chiral column.

^d The reaction temperature is 40 °C.

^e The ee value was not detected.