Studies On Reactions Of Azides With Acroleins

Organic azides are among the most important structural classes of chemical substances,which are applied to organic synthesis,chemical biology,and materials science.Azide could act as a 1,3-dipole in [3+2] cycloaddition reaction with ?,?-unsaturated carbonyl compounds.In this thesis,we studied [3+2] cycloaddition reaction of organic azides with ?-bromoacroleins,and [3+2] cycloaddition reaction of organic azides with ?-alkyl acroleins.1.Catalyst-free [3+2] cycloaddition reactions of organic azides with ?-bromoacroleins: highly regioselective synthesis of 4-formyl-1,2,3-triazolesA general metal-free route to 1,4-disubstituted and 1,4,5-trisubstituted 1,2,3-triazoles was developed.?-Haloacroleins reacted with organic azides both in water and organic solvents at room temperature,to produce 1,4-disubstituted triazoles(up to 99%)with exclusive regioselectivities.This protocol is convenient and scalable with a broad substrate scope including both aliphatic and aromatic azides.The resulting triazoles exhibited an aldehyde group at the C4 position and demonstrated synthetic utilizations.One 1,2,3-triazole compound containing diastereotopic protons was also identified.2.TfOH-promoted reactions of ?-haloacroleins with organic azides: highly regioselective synthesis of 4-formyl-1,2,3-triazolesA facile route to 1,4-disubstituted and 1,4,5-trisubstituted 1,2,3-triazoles was developed.In the presence of TfOH,?-haloacroleins reacted with organic azides quickly at low temperatures to produce high-yield triazoles(up to 99%)with exclusive regioselectivities.The resulting triazoles exhibited an aldehyde group at the C4 position and demonstrated synthetic utilizations.Two axial chiral 1,2,3-triazole compounds were also identified.3.TfOH-promoted reactions of ?-alkylacroleins with organic azides: a new synthetic route to enaminalsEnaminals(?-enaminals)are important compounds that have been utilized for the synthesis of various heterocyclic compounds such as furans,pyrans,pyrroles,pyridines,pyrazoles,isothiazoles,and isoxazoles.Herein a TfOH promoted synthetic route to ?-substituted and ?(11)?-disubstituted enaminals was developed.In the presence of TfOH,?-substituted acroleins reacted with organic azides,and providing enaminals in high yield(up to 93%).