Browsing by Author "Hayashi, Masahiko"

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    Facile and Highly Enantioselective Synthesis of (þ)- and (-)-Fluvastatin and Their Analogues
    (2010-08) Zacharia, James T.; Tanaka, Takanori; Hayashi, Masahiko
    Statins represent a class of drugs that are capable of regulating the biosynthesis of cholesterol by inhibiting the enzyme that reduces 3-hydroxy-3-methylglutaric acid to mevalonic acid, namely, the HMG-CoA reductase inhibitors. Since the introduction of pravastatin by Sankyo and lovastatin by Merck to the pharmaceutical market, this class of drugs has been in eminent demand. Due to the importance of these drugs, various synthetic strategies aimed at the construction of statins have been reported.Many of these studies have focused on the introduction of the statin side chain.1 During the course of our efforts to develop a facile synthesis of HMG-CoA reductase inhibitors, a three-step linear synthesis of fluvastatin 5 has been identified and successfully implemented. Most of the statins, such as atorvastatin calcium hydrate, simvastatin, and pravastatin sodium, are administered in the optically pure form. However, to our knowledge, fluvastatin has been approved as a racemic form. Actually, Novartis’ group reported manufacturing process for fluvastatin in racemic form.2 As for chiral version, Prasad and his
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    Facile Synthesis of Acacetin-7-O-β-d-Galactopyranoside
    (2011-12) Zacharia, James T.; Hayashi, Masahiko
    Acacetin-7-O-β-d-galactopyranoside (1), a natural flavonoid isolated from flower heads of Chrysanthemum morifolium, has been reported to inhibit the replication of HIV in H9 cells. We achieved the total synthesis of compound 1 by employing a one-pot synthesis of the aglycon. The key reactions in this approach include the modified Baker–Venkataraman reaction and regio- and stereoselective O-glycosylations.
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    Simple Preparation of β-Amino Alcohols Possessing a tert-Butyl Group at the α-Carbon
    (2012) Zacharia, James T.; Tanaka, Takanori; Uesaka, Yumiko; Hayashi, Masahiko
    Simple preparation of β-amino alcohols possessing a tert-butyl group at the α-carbon was achieved. These β-amino alcohols proved to work effectively as catalysts in the enantioselective alkylation of aldehydes.