Stereospecific Reactions of Donor–Acceptor Cyclopropanes with Thioketones: Access to Highly Substituted Tetrahydrothiophenes

Abstract

Lewis-acid-catalyzed reactions of 2-substituted cyclopropane 1,1-dicarboxylates with thioketones are described. Highly substituted tetrahydrothiophenes with two adjacent quaternary carbon atoms were obtained in a stereospecific manner under mild conditions and in high yield when using AlCl as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur-bridged [n.2.1] bicyclic ring systems. Conversion of selenoketones, the heavier analogues, under similar conditions resulted in the formation of various tetrahydroselenophenes.

An Expeditious Route to trans‐Configured Tetrahydrothiophenes Enabled by Fe(OTf)3‐Catalyzed [3+2] Cycloaddition of Donor–Acceptor Cyclopropanes with Thionoesters

“…2‐Naphthyl group could be used as substrate ( 3 ad ). Previously unexplored highly coordinative thiocarbonyls having heteroaromatic functionality could be applied and products ( 3 ae , 3 af ) were isolated in moderate yields with high diastereoselectivities using 30 mol % catalyst . Useful intermediate 3 ag having ferrocenyl group was obtained in high yield, verifying synthetic utility of the present catalysis .…”

Construction of Fused‐oxa‐[n.2.1] Skeletons by Tandem Intramolecular [3+2] Cycloaddition/O‐H Insertion/Ester Exchange of Cyclopropanes with Diazocarbonyls

“…In order to improve the reaction yield, a series of Lewis acids was then tried as catalysts. The product was not detected when catalysts Cu(OTf) 2 , CuCl, and BF 3 ·Et 2 O were used, respectively (entries [7][8][9]. The product was not detected when catalysts Cu(OTf) 2 , CuCl, and BF 3 ·Et 2 O were used, respectively (entries [7][8][9].…”

“…When the catalysts Yb(OTf) 3 , Nb(OTf) 3 , La(OTf) 3 , SnCl 4 , and MgI 2 were employed as the promotors, the product could be obtained smoothly, but the yields were not over that of entry 1. The product was not detected when catalysts Cu(OTf) 2 , CuCl, and BF 3 ·Et 2 O were used, respectively (entries [7][8][9]. Further improvement of the yield was realized by the optimization of solvents.…”

“…[6] The aliphatic group was also used as a donor in DÀ A cyclopropane chemistry as well as aryl, N or O groups. [7] Johnson and co-workers observed a high diastereoselectivity in the intermolecular reactions of carbonyls with DÀ A cyclopropanes to construct THF derivatives. [8] Further, the intramolecular cross-cycloaddition reaction of DÀ A cyclopropanes with carbonyls, developed by Wang and co-workers, demonstrated an important strategy for the construction of the oxa-[n. 2.1] skeletons and was used in the synthesis of natural products and bioactive molecules.…”

Diversity of Lawesson's Reagent: Advances and Scope

“…Though some reports consisting of multistep reactions did not solely depend on LR for the construction of heterocyclic framework but still LR played therein crucial role for the synthesis of attractive scaffolds. These included the synthesis of NIR dye, HN7‐S ( 102 ) and library of functionalized 1,4‐thiazepines ( 105 ) in the area of pharmaceuticals, and bicyclic seven‐and eight membered ring systems containing sulfur bridge ( 108 ) (Scheme ).…”