Work

Chemo- and Regioselective 1,3-Dipolar Cycloaddition of Nitrile Imines to 5-Arylmethylene-2-methylthiohydantoins

Year: 2026

Type: article

Abstract: 1,3-Dipolar cycloaddition reactions of nitrile imines are a powerful tool for the construction of spirocyclic frameworks, yet controlling chemoselectivity remains challenging when dipolarophiles contain multiple reactive sites. In this study, we investigated the cycloaddition of nitrile imines with 5-arylmethylene-2-methylthiohydantoins, which possess both exocyclic C=C and endocyclic C=N bonds. Nitrile imines were generated from hydrazonoyl chlorides under basic conditions and reacted with the thiohydantoin substrates under optimized reaction conditions. The cycloaddition proceeded smoothly, affording spiro-fused thiohydantoin–pyrazoline derivatives. In all cases, the reaction occurred selectively at the exocyclic C=C bond, while the C=N bond remained unreactive even in the presence of excess dipole. This chemoselectivity is attributed to the greater steric accessibility of the exocyclic double bond. These results clarify key factors governing nitrile imine chemoselectivity and provide a reliable approach to structurally complex spirocyclic thiohydantoin derivatives.

Source: Organics

DOI: 10.3390/org7010007

Authors: Maria E. Filkina, Lev A. Lintsov, Victor A. Tafeenko, Maxim E. Kukushkin, Elena K. Beloglazkina

Institution: Lomonosov Moscow State University

Language: English

Topic: Organic Chemistry Cycloaddition Reactions

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,207

Funder: Lomonosov Moscow State University