1638264-47-7Relevant academic research and scientific papers
Stereoselectivity Inversion by Water Addition in the ?SO3H-catalyzed Tandem Prins-Ritter Reaction for Synthesis of 4-amidotetrahydropyran Derivatives
Agabekov, Vladimir E.,Freire, Cristina,Kravtsova, Anna V.,Li-Zhulanov, Nikolai S.,M?ki-Arvela, P?ivi,Murzin, Dmitry Yu.,Peixoto, Andreia F.,Salakhutdinov, Nariman F.,Sandberg, Thomas,Sidorenko, Alexander Yu.,Volcho, Konstantin P.
, (2020)
A range of heterogeneous -SO3H functionalized catalysts including carbon and halloysite nanotubes, commercial K10 clay, Amberlyst-15 etc. was investigated for the first time using as a model the Prins-Ritter reaction of (?)-isopulegol with benzaldehyde and acetonitrile producing 4-amido derivatives of octahydro-2H-chromenes (as (S)- and (R)-diastereomers). A strong effect of water addition prior the reaction on the overall selectivity and the ratio of isomers in the case of heterogeneous and homogeneous (p-toluenesulfonic acid) catalysis was found for the first time. The yield of the (R)-diastereomer sharply increased with increasing amount of added water, while the S-isomer prevailed with a minimum amount of added water. Experimental results and DFT calculations clearly indicate a kinetic control for R-amide formation. Typically synthesis of 4-amidooctahydro-2H-chromenes requires subzero temperatures and toxic catalysts, which were avoided in the current work. Nevertheless, the yield of the desired products (up to 83 %) at 30 °C after water addition exceeded the values reported previously. Thus, adding water is a simple and a very effective method for controlling both the yield and stereoselectivity of the Prins-Ritter reaction products under mild conditions.
First example of a Prins-Ritter reaction on terpenoids: A diastereoselective route to novel 4-amido-octahydro-2H-chromenes
Sarmah, Barnali,Baishya, Gakul,Baruah, Rajani K.
, p. 22387 - 22397 (2014/06/23)
(-)-Isopulegol was subjected to a triflic acid-promoted three-component Prins-Ritter reaction with a series of aldehydes to produce a library of novel 4-acetamido-octahydro-2H-chromene derivatives in good yields and high diastereoselectivities. This journal is the Partner Organisations 2014.
