Beilstein J. Org. Chem.2022,18, 167–173, doi:10.3762/bjoc.18.18
Estelle Silm Ivar Jarving Tonis Kanger Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia 10.3762/bjoc.18.18 Abstract An asymmetric Michael reaction between cyclopentane-1,2-dione and alkylidene oxindole was studied in the
presence of a multifunctional squaramide catalyst. Michael adducts were obtained in high enantioselectivities and in moderate diastereoselectivities.
Keywords: cyclopentane-1,2-dione; enantioselective catalysis; Michael addition; organocatalysis; squaramide; Introduction
Diketones are generally very
in carbohydrate chemistry [15]. Cyclic six-membered 1,2-diketones have been shown to react with benzylidene malononitriles [7][16], β-nitrostyrenes [17] and substituted propionaldehydes [18]. For a while, there were no examples related to cyclopentane-1,2-dione (CPD). In 2004, the first instance of
Beilstein J. Org. Chem.2016,12, 1647–1748, doi:10.3762/bjoc.12.162
(Table 6). These γ-lactone acids are valuable substrates for the synthesis of compounds with potentially useful pharmacological properties, such as homocitrates, alkyl- and aryl-substituted nucleosides [270][271][272].
The reaction starts with an asymmetric epoxidation of the substituted cyclopentane-1,2
-dione 87a to form epoxide 89a. The second step involves the Baeyer–Villiger oxidation of epoxide 89a to peroxide 90a followed by the rearrangement into intermediate 91a. The latter is hydrolyzed by H2O to form dicarboxylic acid 92a, which is cyclized under the acidic conditions to γ-lactone acid 88a
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Graphical Abstract
Figure 1:
The named transformations considered in this review.