Asymmetric Synthesis of Tertiary 2-Substituted 5-Oxotetrahydrofuran-2-carboxylic Acids
摘要:
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/tBuO0H 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. Boc-aminomethyl substitu.ents lead to beta-amino acid analogues and Boc-aminoethyl substituent to gamma-amino acid analogues as well as spiro-lactonelactams. A direct, two-step procedure for homocitric acid synthesis is described.
Asymmetric oxidation of 3-alkyl-1,2-cyclopentanediones. Part 1: 3-Hydroxylation of 3-alkyl-1,2-cyclopentanediones
摘要:
3-Alkyl-1,2-cyclopentanediones undergo asymmetric 3-hydroxylation with the Sharpless Ti-complex resulting in enantiomeric 3-hydroxy carbonyl compounds with ee up to 95% in yields of 22-40%. (C) 2002 Elsevier Science Ltd. All rights reserved.
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 ringcleavage products 2-alkyl-γ-lactone acids, in high enantioselectivity (∼95% ee) and satisfactory isolated yields (up to 55%).
Ti(O i Pr)4 /酒石酸二乙酯/ t BuOOH体系氧化3-烷基-1,2-环戊二酮,生成羟化的环裂解产物2-烷基-γ-内酯酸,对映体选择性高(〜95%ee),令人满意单产(最高55%)。
Aerobic cascade oxidation of substituted cyclopentane-1,2-diones using metalloporphyrin catalysts
A method for the aerobic cascade oxidation of cyclopentane-1,2-diones using metal porphyrins as catalysts, yielding hydroxydiacids 2, ketoacid 3 and diketoacids 4 which are the intermediates of important biologically active compounds is reported. This method is operationally simple and can be employed under ambient conditions.
A method for the aerobic oxidation of cyclopentane-1,2-diols to the corresponding diketones over a commercial heterogeneous Pt/C catalyst is described. Unsubstituted and 3- or 4-substituted cyclopentane-1,2-diols are oxidized to 1,2-dicarbonyl compounds in good yields under the reported optimized reaction conditions (atmospheric air, 1 mol % of catalyst, 1 equiv of LiOH, aqueous solvents and 60 degrees C temperature). The method is applicable for producing cyclopentane-1,2-diketones in a scalable manner. (C) 2014 Elsevier Ltd. All rights reserved.
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 gamma-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). (c) 2006 Elsevier Ltd. All rights reserved.