39613-92-8Relevant articles and documents
Evaluation of chiral amino acid discrimination by a permethylated cyclic tetrasaccharide, cyclo-{→6)-α-D-Glcp-(1→3)-α-D-Glcp- (1→6)-α-D-Glcp-(1→3)-α-D-Glcp-(1→}, using FAB mass spectrometry
Shizuma, Motohiro,Kiso, Taro,Terauchi, Hisashi,Takai, Yoshio,Yamada, Hitoshi,Nishimoto, Tomoyuki,Ono, Daisuke,Shimomura, Osarnu,Nomura, Ryoki,Miwa, Yoshikatsu,Nakamura, Masaki,Nakano, Hirofumi
, p. 1054 - 1055 (2008)
The novel cyclic oligosaccharide, permethylated tetrasaecharide (CTS), determinates the enantiomers of chiral amino acid isopropyl ester hydrochlorides. Copyright
Re-Engineering Organocatalysts for Asymmetric Friedel-Crafts Alkylation of Indoles through Computational Studies
Gerosa, Gabriela G.,Marcarino, Maribel O.,Spanevello, Rolando A.,Suárez, Alejandra G.,Sarotti, Ariel M.
, p. 9969 - 9978 (2020/09/03)
The discovery of efficient organocatalysts is generally carried out by thorough experimental screening of different candidates. We recently reported an efficient organocatalyst for iminium-ion-based asymmetric Diels-Alder reactions following a rational design approach. This result encouraged us to test this optimal catalyst in the mechanistically related Friedel-Crafts alkylation of indoles, but to our surprise, almost null enantioselectivity was observed. The results did not significantly improve with structurally related catalysts, and a totally unexpected facial selectivity inversion was also noticed. Using DFT calculations by modeling the competing transition structures with ONIOM, we could unravel the origins of those findings, further employed to predict the most efficient catalyst for this new transformation. The computational results were validated experimentally (up to 92:8 er), providing another successful example of a general strategy to accelerate catalyst development which still remains underexplored.
Stereoselective Synthesis of Sofosbuvir through Nucleoside Phosphorylation Controlled by Kinetic Resolution
Cini, Elena,Barreca, Giuseppe,Carcone, Luca,Manetti, Fabrizio,Rasparini, Marcello,Taddei, Maurizio
, p. 2622 - 2628 (2018/04/30)
The preparation of Sofosbuvir, the potent key component of recent Hepatitis C (HCV) infection therapies, is reported. The process is based on the dynamic kinetic resolution of the stereochemically unstable isopropyl-2-{[chloro(phenoxy)phosphoryl]-amino}propanoate (8). A high stereoselectivity was obtained when the right protective group for 3′-OH was chosen. Ester and carbonate-based protective groups gave lower stereoselectivities, but benzyl protection allowed the phosphorylation to occur with a 92:8 ratio in favour of the product with the right configuration at the P-stereogenic centre. Starting from the γ-lactone of 2-deoxy-2-fluoro-2-methylpentonic acid, the synthesis was accomplished in eight steps in 40 % overall yield using commercially available reagents, and without any enzymatic or chemical resolution technique.