Asymmetric Synthesis of Axially Chiral Phosphamides via Atroposelective N-Allylic Alkylation

Axially chiral anilide compounds are an emerging but scarcely investigated class of stereogenic molecules with potential applications as biologically active scaffolds. Because of the lower rotation barriers, the synthesis of these compounds is a challenging task. Furthermore, the status of the limited structure type of chiral anilide constrains the latent capacity of the C–N axis as a chiral source in the application of asymmetric synthesis. Herein, we disclose an efficient protocol for the construction of the rationally designed axially chiral phosphamides via atroposelective N-allylic alkylation reaction of MBH carbonates and phosphamides. The simple hydroquinidine catalyst proves to be most efficient in this artroposelective strategy, delivering the desired axially chiral phosphamides in good yields and high enantioselectivities. In addition, a phosphamide compound, which contains both P-stereogenic center and C–N axial chirality, can be obtained by this method through a kinetic resolution process. Because of the large steric diaryl phosphoryl group, the synthesized axially chiral anilide has a large rotational barrier. As a demonstration, current studied axially chiral ortho-iodine substituted phosphamides could act as efficient chiral hypervalent iodine(III) catalysts for the asymmetric oxidative dearomatization of phenols. Moreover, a speculative model, which can explain the enantiocontrol, was proposed based on the experimental observation and theoretical calculation.