Iron- and bismuth-catalyzed asymmetric Mukaiyama aldol reactions in aqueous media

We have developed asymmetric Mukaiyama aldol reactions of silicon enolates with aldehydes catalyzed by chiral Fe II and Bi III complexes. Although previous reactions often required relatively harsh conditions, such as strictly anhydrous conditions, very low temperatures (-78 C), etc., the reactions reported herein proceeded in the presence of water at 0 C. To find appropriate chiral water-compatible Lewis acids for the Mukaiyama aldol reaction, many Lewis acids were screened in combination with chiral bipyridine L1, which had previously been found to be a suitable chiral ligand in aqueous media. Three types of chiral catalysts that consisted of a Fe II or Bi III metal salt, a chiral ligand (L1), and an additive have been discovered and a wide variety of substrates (silicon enolates and aldehydes) reacted to afford the desired aldol products in high yields with high diastereo- and enantioselectivities through an appro- priate selection of one of the three catalytic systems. Mechanistic studies elucidated the coordination environments around the Fe II and Bi III centers and the effect of additives on the chiral catalysis. Notably, both Brønsted acids and bases worked as efficient additives in the Fe II-catalyzed reactions. The assumed catalytic cycle and transition states indicated important roles of water in these efficient asymmetric Mukaiyama aldol reactions in aqueous media with the broadly applicable and versatile catalytic systems

水中における有機反応の新展開

学位の種別: 課程博士審査委員会委員 : (主査)東京大学教授 小林 修, 東京大学教授 中村 栄一, 東京大学教授 菅 裕明, 東京大学教授 西原 寛, 東京大学教授 塩谷 光彦University of Tokyo(東京大学

Acetaldehyde Silyl Enol Ethers in Enantioselective Mukaiyama Aldol Reactions: Enzyme-Like Organocatalysis in Action

Touched for the very first time! It is herein highlighted how acetaldehyde silyl enol ethers undergo enantioselective Mukaiyama aldol reaction with aliphatic and aromatic aldehydes. The chemistry relies on the use of the highly efficient and substrate-selective imidodiphosphorimidate catalyst, which displays some of the features of enzymatic catalysis

Upregulation of an Artificial Zymogen by Proteolysis

Regulation of enzymatic activity is vital to living organisms. Here, we report the development and the genetic optimization of an artificial zymogen requiring the action of a natural protease to upregulate its latent asymmetric transfer hydrogenase activity

Induction of apoptosis by HBI-8000 in adult T-cell leukemia/lymphoma is associated with activation of Bim and NLRP3

Adult T-cell leukemia/lymphoma (ATL) is an aggressive T-cell malignancy caused by human T-cell lymphotropic virus 1. Treatment options for acute ATL patients include chemotherapy, stem cell transplantation, and recently the anti-chemokine (C-C motif) receptor 4 antibody, although most patients still have a poor prognosis and there is a clear need for additional options. HBI-8000 is a novel oral histone deacetylase inhibitor with proven efficacy for treatment of T-cell lymphomas that recently received approval in China. In the present study, we evaluated the effects of HBI-8000 on ATL-derived cell lines and primary cells obtained from Japanese ATL patients. In most cases HBI-8000 induced apoptosis in both primary ATL cells and cell lines. In addition, findings obtained with DNA microarray suggested Bim activation and, interestingly, the contribution of the NLR family, pyrin domain containing 3 (NLRP3) inflammasome pathway in HBI-8000-induced ATL cell death. Further investigations using siRNAs confirmed that Bim contributes to HBI-8000-induced apoptosis. Our results provide a rationale for a clinical investigation of the efficacy of HBI-8000 in patients with ATL. Although the role of NLRP3 inflammasome activation in ATL cell death remains to be verified, HBI-8000 may be part of a novel therapeutic strategy for cancer based on the NLRP3 pathway

Enantioselective synthesis of allylboronates and allylic alcohols by copper-catalyzed 1,6-boration

Chiral secondary allylboronates are obtained in high enantioselectivities by the copper-catalyzed 1,6-boration of electron-deficient dienes with B2(pin)2. The reactions proceed efficiently using catalyst loadings as low as 0.0049 mol%. The allylboronates may be oxidized to the allylic alcohols, and can be used in stereoselective aldehyde allylborations. This process was applied to a concise synthesis of atorvastatin

Site-selective incorporation and ligation of protein aldehydes

The incorporation of aldehyde handles into proteins, and subsequent chemical reactions thereof, is rapidly proving to be an effective way of generating homogeneous, covalently linked protein constructs that can display a vast array of functionality. In this review, we discuss methods for introducing aldehydes into target proteins, and summarise the ligation strategies for site-selective modification of proteins containing this class of functional handles

Switchable synthesis of Z-homoallylic boronates and E-allylic boronates by enantioselective copper-catalyzed 1,6-boration

The enantioselective Cu-catalyzed 1,6-boration of (E,E) α,β,γ,δ-unsaturated ketones is described, which gives homoallylic boronates with high enantiomeric purity and unexpectedly high Zselectivity. By changing the solvent, the outcome can be altered to give E-allylic boronates