Synthesis of Chiral Poly(silyl ether)s via CuH-Catalyzed Asymmetric Hydrosilylation Polymerization of Diketones with Silanes.

The precise synthesis of chiral poly(silyl ether)s remains a challenge, in contrast to the well-studied preparation of poly(silyl ether)s. Herein, an unprecedented approach for the synthesis of optically active poly(silyl ether)s with main-chain chirality has been developed via CuH-catalyzed hydrosilylation polymerization of diketones and silanes. The polymerization features low catalyst loading, mild condition, and broad substrate scope, including a wide range of aromatic diketones and heteroaromatic diketones with excellent yields and enantioselectivities (up to 98% yield and 99% ee). Thermal analysis indicated chiral poly(silyl ether)s exhibit good thermal properties. These enantiomerically enriched poly(silyl ether)s with good thermal stability have a promising application in chiral separation.

Divergent Total Syntheses of C3 a-C7' Linked Diketopiperazine Alkaloids (+)-Asperazine and (+)-Pestalazine†A Enabled by a Ni-Catalyzed Reductive Coupling of Tertiary Alkyl Chloride.

Short gram-scale asymmetric syntheses of asperazine, pestalazine A, and their unnatural congeners thereof, have been achieved in ≈10 steps by using readily accessible starting materials. The nickel-catalyzed reductive coupling protocol was utilized as a key step for the direct construction of C3asp3 -C7'sp2 bond furnishing the diaryl-substituted quaternary carbon centers with remarkable steric hindrance. The streamlined access to this core structure of heterodimeric tryptophans under the mild reaction conditions, makes this strategy hold a great promise in the concise synthesis of other relevant oligomeric pyrroloindoline alkaloids with unique C3a-C7' linkages.