Fused azole-thiazolines via one-pot cyclization of functionalized N-heterocyclic carbene precursors
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Updated: Dec 26, 2025

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
Qiaoqiao Teng1, Chandan Singh, Yuan Han
1Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Republic of Singapore. chmhhv@nus.edu.sg.
Abstract:
A one-pot two-step methodology was exploited to synthesize fused thiazoline-azolium salts via reactions of bromoalkyl-azolium salts with KSCN and NaOH. The synthetic feasibility and versatility was demonstrated by the high yield (>80%) preparation of 13 salts with different backbones, linkers and substituents. Using methylpropionato as an N-protecting group, the resulting salts could be further derivatized to their neutral azole-thiazolines. The reaction sequence proceeds via (i) Br → SCN substitution, (ii) N-heterocyclic carbene formation, (iii) carbene attack of the S atom and CN- displacement in the alkyl-S-C[triple bond, length as m-dash]N unit, and (iv) methyl acrylate elimination.
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