Sc(OTf)₃‐Catalysed [3+3] Annulation of Cyclopropane 1,1‐Diesters with Mercaptoacetaldehyde: A Facile Strategy for the Synthesis of Tetrahydrothiopyranols

Abstract

A catalytic [3+3] annulation of cyclopropane 1,1‐diesters with in‐situ‐generated mercaptoacetaldehyde for the synthesis of polyfunctionalized tetrahydrothiopyran derivatives has been developed. A ring‐opening/aldol cascade reaction catalysed by Sc(OTf)3 (10 mol‐%) gave a series of tetrahydrothiopyranols in good yields. Simple derivatization of the products gave some useful compounds.

Exploiting Heavier Organochalcogen Compounds in Donor–Acceptor Cyclopropane Chemistry

“…Further DBU-induced derivatization delivers fully substituted thiophene-2-carbaldehydes 68 in up to 82% yield over two steps (Scheme ). A similar approach was published by Zhang et al using classical D–A cyclopropane dicarboxylates under Sc­(OTf) 3 catalysis focusing on the formation of structurally diverse tetrahydrothiopyranes . Further investigations by the group of Lin and Feng lead to an asymmetric version employing chiral N , N ′-dioxide ligands.…”

Organocatalytic Enantioselective (4+2) Annulation of Cyclopropane Carbaldehydes with 2‐Mercapto‐1‐Arylethanones

“…[12] Our group has been working considerably on the chemistry of DACs for the last decade and already developed various methodologies for constructing several biologically important heterocyclic motifs, mainly by employing Lewis or Brønsted acid catalysis. [13] Additionally, donor-acceptor cyclopropanes have been used for the synthesis of dihydrothiopyranols [14] and indolefused tricyclic dihydrothiopyran in the presence of Lewis acid. [15] After the successful exploration of these methodologies, our group was motivated to work on the field of more sustainable strategies like organocatalysis, which offers several advantages, such as operational simplicity, low toxicity, and ease of handling, making them attractive for the construction of complex organic molecules.…”

Acetic Acid Mediated Regioselective [3 + 3] Cycloaddition of Substituted Cyclopropane-1,1-dicarbonitriles with 1,4-Dithiane-2,5-diol

“…As efficient building blocks, various D–A cyclopropanes could form 1,3-dipoles to afford annulation reactions with S-containing partners to synthesize functionalized tetrahydrothiopyrans. For example, in 2015, Zhang and co-workers contributed that a Sc­(OTf) 3 -catalyzed [3 + 3] annulation of D–A cyclopropanes with in situ generated mercaptoacetaldehyde was particularly effective in yielding a new set of polyfunctionalized tetrahydrothiopyran derivatives (Scheme , i) . Soon afterward, the same [3 + 3] annulation in the presence of a N , N ′-dioxide-Sc­(III) complex as the catalyst also was investigated to provide the corresponding chiral tetrahydrothiopyranols .…”