Department of Pharmacy, University of Pisa, via Bonanno 33, 56126 Pisa, Italy.
Department of Chemistry and Industrial Chemistry, University of Pisa, via Moruzzi 3, 56124 Pisa, Italy.
Molecules. 2020 Apr 20;25(8):1903. doi: 10.3390/molecules25081903.
γ- and δ-Oxoesters are easily available starting materials that have been sparingly used in some organocatalyzed reactions proceeding with a high enantioselectivity. In our experimentation we found that the use of these compounds as the enolizable (nucleophilic) component in organocatalyzed Mannich-type reactions using in situ-generated cyclic -acyl iminium ions gave low diastereoselectivity and low to moderate values of enantioselectivity. This significant drop of facial selectivity with respect to simple aliphatic aldehydes has been rationalized by means of density functional theory (DFT) calculations.
γ- 和 δ-氧代酯是容易获得的起始原料，它们在一些具有高对映选择性的有机催化反应中很少被使用。在我们的实验中，我们发现这些化合物作为烯醇化（亲核）组分，在使用原位生成的环状酰亚胺离子的有机催化曼尼希型反应中，其非对映选择性较低，对映选择性为低至中等。相对于简单的脂肪醛，这种显著降低的面选择性可以通过密度泛函理论（DFT）计算来解释。
