A DFT study of 1,3-dipolar cycloadditions of cyclic nitrones to unsaturated lactones. Part II

The 1,3-dipolar cycloadditions of cyclic nitrones to five-membered unsaturated lactones are studied. Special attention was focused on a single and double asymmetric induction when one or both components were chiral. The energies of the cycloaddition reactions are investigated through application of molecular orbital calculations at the B3LYP/6-31+G(d) theory level. A study of the different reactants’ approaches and their conformational aspects revealed the stereochemical preferences of these reactions. The results of these calculations correspond well with the previously reported experimental data.

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(1aS,2R,4aR,4bS)-2-Hydroxymethyl-hexahydrofuro[3,4-d]pyrrolo[1,2-b]isoxazol-4(3H)-oneC9H13NO4[α]D25=-67.4 (c 0.6, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (1aS,2R,4aR,4bS)

(1aS,2R,4aR,4bR)-2-(tert-Butyldiphenylsilyloxymethyl)-hexahydrofuro[3,4-d]pyrrolo[1,2-b]isoxazol-4(3H)-oneC25H31NO4Si[α]D25=+37.5 (c 1.2, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (1aS,2R,4aR,4bR)

(1aS,2R,4aR,4bS)-2-(tert-Butyldiphenylsilyloxymethyl)-hexahydrofuro[3,4-d]pyrrolo[1,2-b]isoxazol-4(3H)-oneC25H31NO4Si[α]D25=-37.7 (c 1.06, CH2Cl2)Source of chirality: asymmetric synthesisAbsolute configuration: (1aS,2R,4aR,4bS)