Affiliation:
1. University of Lodz Department of Organic & Applied Chemistry Tamka 12 91-403 Łodź Poland
2. The Bio-Med-Chem Doctoral School of the University of Łodź and Łodź Institutes of the Polish Academy of Sciences Faculty of Biology and Environmental Protection University of Łodź 90237 Łódź Poland
3. University of Lodz Department of Physical Chemistry Pomorska 163–165 90-236 Łodź Poland
4. Institute of Organic Chemistry Albert-Ludwigs-Universität Freiburg Albertstraße 21 79104 Freiburg im Breisgau Germany
Abstract
AbstractReactions of dimethyl 2‐arylcyclopropane‐1,1‐dicarboxylates, used as representatives of D‐A cyclopropanes, with tropothione were carried out in the presence of scandium triflate as a catalyst, under mild conditions (CH2Cl2 solution, rt). The anticipated (8+3)‐cycloaddition products, cycloheptatriene fused thiopyrans, were obtained in good to excellent yields. Cycloadditions occurred with complete diastereoselectivity and in all cases single diastereomers were formed. Structures of isolated cycloadducts were established based on spectroscopic data and in two cases they were unambiguously confirmed by single crystal X‐ray diffraction analysis. In contrast to an analogous (8+3)‐cycloaddition reported for parent tropone, which was performed in the presence of Ni(ClO4)2, no 1,3‐H shift leading to products possessing a CH2 moiety located within the seven‐membered ring was observed.
Funder
Studienstiftung des Deutschen Volkes
Subject
Organic Chemistry,Physical and Theoretical Chemistry