114289-01-9Relevant academic research and scientific papers
MN(III)-based oxidative free-radical cyclizations of substituted allyl α-methyl-β-ketoesters: Syntheses, DFT calculations, and mechanistic studies
Sung, Kuangsen,Yuan Wang, Yu
, p. 2771 - 2778 (2003)
The cyclizations of the substituted allyl α-methyl-β-ketoester radicals 11, 14, and 18 were studied by the DFT method at the UB3LYP/6-31G* level; the results show that the cis cyclization is easier than the corresponding trans cyclization, but the generated cis radicals are not necessarily more stable than the corresponding generated trans radicals after the cyclizations. The free-radical cyclizations of 11, 14, and 18 in the presence of Mn(OAc)3 in acetic acid or acetonitrile are all reversible and operate under thermodynamic control, and stereoselectivity of the cyclizations depends on relative stability of the cyclization-generated radicals. Therefore, the oxidative free-radical cyclization of allyl α-methyl-β-ketoester 5a with Mn(OAc)3 gives a cis product as a major product, while the same oxidative free-radical cyclizations of substituted allyl α-methyl-β-ketoesters 5b and 5c with Mn(OAc)3 produce trans products as major products.
