Asymmetric synthesis of tertiary 2-substituted 5-oxotetrahyrofuran-2- carboxylic acids
3-Substituted 1,2-cyclopentanediones 1 were transformed to 2-substituted 5-oxotetrahydrofuran-2-carboxylic acids 2 using a catalytic process with 0.2-0.3 equivalent of Ti(OiPr)4/tartaric ester/tBuOOH complex in up to 72% isolated yield and up to 94% ee. Different functional groups in the 3-alkyl substituent of 1 like, hydroxy, ether, Boc-amino and ester groups are tolerated.
Paju, Anne,Oja, Karolin,Matkevits, Katharina,Lumi, Priit,Jaerving, Ivar,Pehk, Tonis,Lopp, Margus
Asymmetric synthesis of 2-alkyl-substituted 2-hydroxyglutaric acid γ-lactones
3-Alkyl-1,2-cyclopentanediones 1 are transformed into 2-alkyl-2-hydroxyglutaric acid γ-lactones 3 in up to 83% isolated yields and up to 96% ee, affording a simple access to many bioactive compounds, including diacylglycerol lactones (DAG-lactones).
Paju, Anne,Laos, Marit,J?gi, Artur,P?ri, Malle,J??laid, Raissa,Pehk, T?nis,Kanger, T?nis,Lopp, Margus
p. 4491 - 4493
(2007/10/03)
Asymmetric oxidation of 3-alkyl-1,2-cyclopentanediones. Part 2: Oxidative ring cleavage of 3-alkyl-1,2-cyclopentanediones: Synthesis of 2-alkyl-γ-lactone acids
Ti(OiPr)4/diethyl tartrate/tBuOOH system oxidizes 3-alkyl-1,2-cyclopentanediones resulting in hydroxylated ring cleavage products 2-alkyl-γ-lactone acids, in high enantioselectivity (~95% ee) and satisfactory isolated yields (up to 55%).
Paju, Anne,Kanger, Tonis,Pehk, Tonis,Lindmaa, Rasmus,Mueuerisepp, Aleksander-Mati,Lopp, Margus
p. 1565 - 1573
(2007/10/03)
Asymmetric oxidation of 1,2-cyclopentanediones
Cyclic 3-alkyl-1,2-cyclopentanediones undergo a direct asymmetric oxidation with the DET/Ti(OiPr)4/ tBuOOH oxidative system, resulting in enantiomeric α-hydroxy compounds and ring-cleaved hydroxylated acids (lactones) up to 95% ee. (C) 2000 Elsevier Science Ltd.
Paju, Anne,Kanger, T?nis,Pehk, T?nis,Lopp, Margus
p. 6883 - 6887
(2007/10/03)
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