| Various benzotriazole-mediated methodologies have been developed and applied to synthesize a wide range of biologically and synthetically important compounds.;Chapter 2 describes how acylbenzotriazoles, neutral acylating reagents, exhibit great potential in preparing Weinreb amides. Synthetically important Weinreb amides are synthesized under mild conditions in 71--89% yields.;The work described in chapter 3 represents the first application of acylbenzotriazoles to peptide coupling. The study indicates that acylbenzotriazoles are suitable for peptide synthesis, which not only leads to the formation of peptide bonds in high yield but also maintains the chiral integrity of amino acids.;Synthesis of 3-substituted azirines constitutes a synthetic challenge to chemists. The Neber reaction has been generally used to synthesize azirines but requires the existence of electron-withdrawing group at the alpha-position of the oxime before ring closure. Chapter 3 describes how to introduce the benzotriazolyl group into reaction intermediates to facilitate ring closure in the Neber reaction to give 3-benzotriazolyl azirines, which are very useful precursors for the synthesis of various 3-substituted azirines.;Benzotriazole-assisted aminoalkylation is usually limited to aldehyde substrates with amines. The attempt to extend aminoalkylation to ketones proved successful and various novel N-tertiary alkyl tertiary amines have been synthesized through the addition of benzotriazolys to enamines derived from ketones followed by the nucleophilic replacement of benzotriazolyl group by various alkyl, alkynyl, vinyl, aromatic and heteraromatic organometallic reagents. The details are discussed in chapter 5. |
