- A practical route to enantiopure 3-hydroxy-pyrrolidines: application to a straightforward synthesis of (-)-bulgecinine
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A practical synthesis of enantiopure substituted 3-hydroxy-pyrrolidines is reported. In four steps, starting from commercially available amino acids as chiral educts, this method allows for an efficient preparation of a variety of 3-hydroxy-pyrrolidines, as well as 3-hydroxy-piperidines and azepanes. Application of this methodology for a straightforward asymmetric synthesis of (-)-bulgecinine is also described.
- Toumi, Mathieu,Couty, Fran?ois,Evano, Gwilherm
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p. 1175 - 1179
(2008/09/18)
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- CYCLIC AMINE COMPOUND
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A compound represented by the formula (I) or a salt thereof: (I) wherein the ring A represents a 5- to 8-membered ring which may have additional substituent besides R6, R7 and R8; R1 represents an electron-attracting group; R2, R3, R4 and R5 independently represent a hydrogen atom, a halogen atom, a group attached through a carbon atom, a group attached through a nitrogen atom, a group attached through an oxygen group, or a group attached through a sulfur atom; R6 represents a halogen atom, a group attached through a carbon atom, a group attached through a nitrogen atom, a group attached through an oxygen group, or a group attached through a sulfur atom, and R7 represents a cyano group, a nitro group, an acyl group which may have a substituent, a carboxyl group which may be esterified or amidated, or a hydrocarbon group which may have a substituent, or R6 and R7 together with a carbon atom to which they are attached may form a ring which may have a substituent; and R8 represents a hydrogen atom, a halogen atom, a group attached through a carbon atom, a group attached through an oxygen atom, or a group attached through a sulfur atom. The compound or salt has an excellent androgen receptor modulating effect, and is useful for the prevention/treatment of hypogonadism, partial androgen deficiency in aging male, decline in physical strength, cachexia, osteoporosis and the like.
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Page/Page column 119-120
(2010/11/25)
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- The stereochemical course of addition of allyltrimethylsilane to protected L-alaninals and L-serinals in the presence of Lewis acids. Total synthesis of cis-(2R,3S)-3-hydroxyproline
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The influence of Lewis acids on the diastereoselectivity of the addition of allyltrimethylsilane to variously protected L-alaninals and L-serinals was investigated and high levels of asymmetric induction were achieved. Stereochemical models for rationalisation of the results obtained are proposed. cis-(2R,3S)-3-Hydroxyproline was synthesised starting from N-Cbz, O-TBS-L-serinal, in which the crucial step involves addition of allyltrimethylsilane to the aldehyde in the presence of SnCl4.
- Gryko,Prokopowicz,Jurczak
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p. 1103 - 1113
(2007/10/03)
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- Diastereoselective addition of allyl reagents to variously N-monoprotected and N,N-diprotected L-alaninals
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Diastereoselective C3-elongation processes of N-Boc-, N-Z-, N-Bn-N-Boc-, and N-Bn-N-Z-L-alaninals (Boc = 'BuOCO, Z = PhCH2OCO, Bn = PhCH2) using various allyl reagents, such as allyl bromide in the presence of Zn/aqueous N
- Gryko, Dorota,Jurczak, Janusz
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p. 2705 - 2711
(2007/10/03)
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- A Novel BF3*OEt2-Catalyzed Annulation of N-Cbz-α-Amino Aldehides with Allyltrimethylsilane. Highly Stereoselective Synthesis of Cis-2,3,5-Trisubstituted Pyrrolidines
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In the presence of BF3*OEt2 (0.2 molar equiv), the reactions (-10 deg C, CH2Cl2) of N-Cbz-α-amino aldehydes with allyltrimethylsilane produced pyrrolidines in good yields (70-80percent), with high all-cis stereoselectivity at the C-2, C-3, and C-5 positio
- Kiyooka, Syun-ichi,Shiomi, Yasuhiro,Kira, Haruhide,Kaneko, Yuichi,Tanimori, Shinji
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p. 1958 - 1960
(2007/10/02)
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- Lewis acid-mediated reaction with silyl ketene acetals and allylstannane of the aluminum acetals generated by DIBALH reduction of α-amino acid esters
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The intermediates generated by DIBALH reduction of α-amino acid esters undergo condensation without racemization with silyl ketene acetals and allylstannane in the presence of Lewis acid to afford the corresponding β-hydroxy esters and homoallylic alcohol
- Kiyooka,Suzuki,Shirouchi,Kaneko,Tanimori
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p. 5729 - 5732
(2007/10/02)
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- ALUMINUM-MEDIATED ONE-POT CONVERSION OF α-AMINO ACID ESTERS TO THREO 2-AMINO ALCOHOLS WITH HIGH DIASTEREOSELECTIVITY
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Reduction of N-Cbz α-amino acid esters with DIBAl-H, followed by treatment with Grignard reagent in a one-pot manner gave the corresponding threo 2-amino alcohols with high diastereoselectivity without racemization. KEYWORDS 2-amino alcohol; α-amino acid ester; DIBAL-H reduction; α-amino aldehyde; chelation controll; diastereoselective synthesis; one-pot synthesis
- Kano, Shinzo,Yuasa, Yoko,Yokomatsu, Tsutomu,Shibuya, Shiroshi
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p. 2867 - 2869
(2007/10/02)
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