34119-82-9Relevant articles and documents
C(sp3)-H Bond Arylation and Amidation of Si-Bound Methyl Group via Directing Group Strategy
Han, Jie-Lian,Qin, Ying,Zhao, Dongbing
, p. 6020 - 6026 (2019/06/25)
Silylmethyl functionalization provides a general and efficient access to diverse organosilanes. The traditional methods for silylmethyl functionalization often involved silylmethylmetals or silylmethylhalides. In recent years, a C-H activation strategy has become one of the most attractive alternatives in organic synthesis. We envisioned that the attachment of a coordinating group at silicon of methylsilanes provides the opportunity to modify the silylmethyl group via directed C-H bond functionalization. However, despite employment of silicon tethers bearing a directing group (DG) for C(sp2)-H functionalization has been well established due to the fact that the silicon tethers are easily installable and removable/modifiable, applying this concept toward C(sp3)-H functionalization remains underdeveloped. Herein, we successfully develop IrIII/RhIII-catalyzed C-H bond arylation/amidation of silyl methyl group by using directing group strategy, which constitutes the most powerful access to benzylsilanes and amino-substituted silanes. Moreover, we demonstrated that the pyridine directing group on silicon atom can be easily removed, and the starting materials can also be efficiently recovered, which are different from those of pyridine-directed C-H functionalization of C-bound methyl group.
Enantioselective Aminohydroxylation of Styrenyl Olefins Catalyzed by an Engineered Hemoprotein
Cho, Inha,Prier, Christopher K.,Jia, Zhi-Jun,Zhang, Ruijie K.,G?rbe, Tamás,Arnold, Frances H.
, p. 3138 - 3142 (2019/02/01)
Chiral 1,2-amino alcohols are widely represented in biologically active compounds from neurotransmitters to antivirals. While many synthetic methods have been developed for accessing amino alcohols, the direct aminohydroxylation of alkenes to unprotected, enantioenriched amino alcohols remains a challenge. Using directed evolution, we have engineered a hemoprotein biocatalyst based on a thermostable cytochrome c that directly transforms alkenes to amino alcohols with high enantioselectivity (up to 2500 TTN and 90 % ee) under anaerobic conditions with O-pivaloylhydroxylamine as an aminating reagent. The reaction is proposed to proceed via a reactive iron-nitrogen species generated in the enzyme active site, enabling tuning of the catalyst's activity and selectivity by protein engineering.
Lewis Acid-Catalyzed Addition of Benzophenone Imine to Epoxides Enables the Selective Synthesis and Derivatization of Primary 1,2-Amino Alcohols
Leitch, David C.,Lim, John Jin
, p. 641 - 649 (2018/05/14)
Benzophenone imine was found to be an effective ammonia surrogate for the selective preparation of primary 1,2-amino alcohols from epoxides, including enantiopure epichlorohydrin, in the presence of catalytic Y(OTf)3. High-throughput screening of 48 Lewis acids quickly identified Y(OTf)3 as an effective mediator of the addition reaction under mild conditions. Following acidic hydrolysis, the primary amino alcohol salt is revealed and partitions into the aqueous solution, while the benzophenone byproduct is easily removed by simple extraction with ethyl acetate. These ammonium salts can be directly Boc-protected or further derivatized without isolation to form benzamides and sulfonamides under Schotten-Baumann-type conditions in up to 79% isolated yield over three steps. This methodology has been used to prepare key intermediates for the synthesis of PRMT5 inhibitors with high enantiopurity as well as numerous other amide and sulfonamide derivatives.
