Study On The Green Synthesis Of δ-oxo-α,β-unsaturated Nitriles And Their Applications In Organic Synthesis

In this thesis,the preparation of δ-oxo-α,β-unsaturated nitriles and their applications as intermediates in organic synthesis have been studied.It mainly includes the following two chapters:In the first chapter,an environmentally benign and efficient route for the preparation ofδ-oxo-α,β-unsaturated nitriles was developed.To be specific:tandem reactions of 1,2-allenic ketones with 2-substituted cyanoacetates were found to proceed rapidly and efficiently by using ionic liquid as both promoter and reaction medium.Through these reactions,a series of δ-oxo-α,β-unsaturated nitriles were synthesized with good yields.Compared with literature methods,these procedures showed such advantages as high yields,mild conditions,environmentally benign and reusable solvent.In the second chapter,some novel applications of δ-oxo-α,β-unsaturated nitriles as valuable intermediates in organic synthesis were successfully developed.Specific studies are as follows:1.5-Hydroxypent-2-enenitriles were efficiently prepared via reduction of δ-oxo-α,β-unsaturated nitriles with KBH4.2.Upon treatment with protonic acid,(E)-5-hydroxypent-2-enenitriles could undergo a β-elimination,or an intramolecular Friedel-Crafts reaction to give 2,4-dienenitriles or polysubstituted naphthalenes with high efficiency depending on the nature of the substituents attached on the carbon-carbon double bond.3.By treating with protonic acid,(Z)-5-hydroxypent-2-enenitriles could undergo an intramolecular Pinner reaction to afford a-pyranones efficiently,thus resulting a novel synthetic approach toward pyranone derivatives.In summary,an environmentally friendly method for the preparation of δ-oxo-α,β-unsaturated nitriles was firstly developed in this thesis.In exploring the synthetic applications of the δ-oxo-α,β-unsaturated nitriles,some novel methods for the synthesis of 2,4-dienenitriles,α-pyranones and polysubstituted were successfully developed.