Regioselective Reduction of 1 H-1,2,3-Triazole Diesters

Christopher R Butler; Justin Bendesky; Allen Milton Schoffstall

doi:10.3390/molecules26185589

Regioselective Reduction of 1 H-1,2,3-Triazole Diesters

Molecules. 2021 Sep 15;26(18):5589. doi: 10.3390/molecules26185589.

Authors

Christopher R Butler¹, Justin Bendesky¹, Allen Milton Schoffstall¹

Affiliation

¹ Department of Chemistry and Biochemistry, University of Colorado Springs, Colorado Springs, CO 80918, USA.

Abstract

Regioselective reactions can play pivotal roles in synthetic organic chemistry. The reduction of several 1-substituted 1,2,3-triazole 4,5-diesters by sodium borohydride has been found to be regioselective, with the C(5) ester groups being more reactive towards reduction than the C(4) ester groups. The amount of sodium borohydride and reaction time required for reduction varied greatly depending on the N(1)-substituent. The presence of a β-hydroxyl group on the N(1)-substituent was seen to have a rate enhancing effect on the reduction of the C(5) ester group. The regioselective reduction was attributed to the lower electron densities of the C(5) and the C(5) ester carbonyl carbon of the 1,2,3-triazole, which were further lowered in cases involving intramolecular hydrogen bonding.

Keywords: 1,3-dipolar cycloaddition; 1H-1,2,3-triazole; borohydride reduction; electron density modeling; metal-catalyzed azide-alkyne cycloaddition (CuAAC); regioselective reduction.