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Synthesis of2-Oxazolines Using DAST via Beckmann Rearrangement

作　者: Okello Gabriel
导　师: Xihe Bi
学　校: 东北师范大学
专　业: Organic Chemistry
关键词: oxazoline rearrangement DAST amides reaction cyclization Beckmann heterocyclic Synthesis alcohols cycloaddition intramolecular Rearrangement substituted derivatives diketene amino ylidene aldehydes ether
分类号: O621.25
类　型: 硕士论文
年　份: 2013年
下　载: 2次
引　用: 0次
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内容摘要

In the recent few decades, discovery of the DAST mediated reaction system for organic reactions to form oxazolines has effected drastic and far-reaching changes in the scientific domain. This invention has engrossed the interest of chemists and is increasing our understanding of how a range of organic synthetic processes are enhanced.-its alluring tendency has been marked by numerous applications such as gasoline (petrol and diesel) and lube oil additives, pharmaceutical industries, surface-active agent, corrosion resistant coating, anti-foaming agents, textile chemicals, adhesives and binders, stabilizers for chlorinated hydrocarbons; thus justifying the rigorous research on the oxazoline compound. Today, extraordinary transformations to various natural products and biologically active molecules have been achieved where various oxazolines are useful as intermediates.Oxazoline intermediates entertain a great diversity of reaction patterns that can stand numerous functional groups. Additionally, oxazoline synthetic protocols using DAST are economically captivating procedures as most procedures have been used as surrogate for the traditionally tedious, toxic and sometimes unreliably low product-yielding. In recent progresses, demonstrations from various researchers make free from ambiguity the contributions of the versatility of modern oxazoline synthesis in the development of pharmaceutical libraries, and also in the polymer, material and petroleum industries.In our special case, methodologies used with other systems are mentioned in passing as a justification as to why oxazolines are considered to be species with special powers.Encouraged by the virtues of this, we have conveniently developed a method for the synthesis of highly functionalized2-oxazolines in a one pot component reaction of Ketoximes using DAST via Beckmann rearrangement. Our choice for using DAST was intended for the development of simple, safe and efficient method for their synthesis of oxazolines.In this report we established a novel and efficient route for synthesis of2-oxazolines from Ketoxime substrate. This route involved a one-pot amidation of diketene with different amines at70℃in the presence of toluene to form corresponding amides followed by reacting the amides with K2CO3and DMF at room temperature to form corresponding carboxamides and carboxylates. The carboxamides and carboxylates were then reacted with NH2OH.HCL and NaOAc in presence of ethanol and water to form Ketoximes which were subsequently reacted in one pot uni-molecular synthesis with DAST and dichloromethane at room temperature to form corresponding2-oxazolines via Beckmann rearrangement.With the above pathway a simple one-pot unimolecular component reaction approach for the synthesis of highly functionalized2-oxazolines in excellent yields from corresponding Ketoximes was developed. Our utility of DAST as the reagent via Beckmann rearrangement proved to be another extraordinary transformation of Ketoximes to various oxazoline derivatives. Added to its excellent conversions, the superiority of the Ketoxime is culminated by its ready availability. The reaction was not only achieved in a short time but also under favorable conditions like room temperature.

全文目录

ABSTRACT  4-6
LIST OF ABBREVIATIONS / ACRONYMS  6-10
TABLE OF CONTENTS  10-12
CHAPTER 1  12-20
  1.0 INTRODUCTION  12
  1.1 GENERAL  12
  1.2 OCCURANCE IN NATURE  12-13
  1.3 THE OXAZOLINE SUBSTRUCTURE  13-15
  1.4 USE OF DAST IN AS A REAGENT IN SYNTHESIS OF OXAZOLINES  15-16
  1.5 BECKMANN REARRANGEMENT  16-17
  1.6 JUSTIFICATION  17-19
  1.7 AIMS AND OBJECTIVES  19-20
CHAPTER 2  20-33
  2.0 LITERATURE REVIEW  20
  2.1 SYNTHETIC STRATEGIES OF OXAZOLINES  20
  2.2 SYNTHESIS STRATEGIES WITHOUT THE USE OF DAST  20-27
    2.2.1 Direct Methods-Carboxylic Acids  20-21
    2.2.2 Synthesis of oxazolines from Aldehydes  21-22
    2.2.3 Hydroxyamides-Hydroxyl Activation  22-25
    2.2.4 Eneamides-Alkene Activation  25-26
    2.2.5 Epoxide/Aziridine Ring Opening Reactions  26-27
    2.2.6 Electrocyclic Reactions  27
  2.3 SYNTHETIC STRATEGIES WITH THE USE OF DAST  27-31
  2.4 SYNTHESIS WITH DAST VIA BECKMANN REARRANGEMENT  31-33
CHAPTER 3  33-42
  3.0 EXPERIMENTAL METHODS, RESULTS AND DISCUSSION  33
  3.1 SYNTHESIS OF KETOXIMES AND ALDOXIMES  33-39
    3.1.1 BACKGROUND  33-34
    3.1.2 GENERAL INFORMATION  34
    3.1.3 GENERAL PROCEDURE FOR PREPARATION OXAZOLINE FROM DIKETENE  34-39
  3.2 Procedure for preparation of product  39-41
  PROPOSED MECHANISM  41-42
CHAPTER 4 CONCLUSION  42-50
  4.0 ANALYTICAL DATA OF THE KETOXIMES AND 2-OXAZOLINES  43
  4.1 Ketoximes  43-44
    4.1.1 1-(1-(hydroxyimino)ethyl)-N-phenylcyclopropanecarboxamide(4a)  43
    4.1.2 N-benzyl-1-(1-(hydroxyimino)ethyl)cyclopropanecarboxamide  43
    4.1.3 1-(1-(hydroxyimino)ethyl)-N-(p-tolyl)cyclopropanecarboxamide  43
    4.1.4 1-(1-(hydroxyimino)ethyl)-N-(naphthalen-1-yl)cyclopropanecarboxamide  43
    4.1.5 N-(tert-butyl)-1-(1-(hydroxyimino)ethyl)cyclopropanecarboxamide  43-44
  4.2 Oxazoline products  44-45
    4.2.1 (Z)-N-(5-methyl-6-oxa-4-azaspiro[2.4]hept-4-en-7-ylidene)aniline  44
    4.2.2 (Z)-4-methyl-N-(5-methyl-6-oxa-4-azaspiro [2.4]hept-4-en-7-ylidene)aniline  44
    4.2.3 (Z)-N-(5-methyl-6-oxa-4-azaspiro[2.4] hept-4-en-7-ylidene)naphthalen-2-amine  44
    4.2.4 (Z)-2-methyl-N-(5-methyl-6-oxa-4-azaspiro [2.4]hept-4-en-7-ylidene)propan-2-amine  44
    4.2.5 7-methyl-5-phenyl-5,6-diazaspiro[2.4]hept-6-en-4-one  44-45
  4.3 ~1H-AND ~(13)C-NMR SPECTRA COPIES  45-50
ACKNOWLEDGEMENT  50-52
DEDICATION  52-53
REFERENCES  53-57

Synthesis of2-Oxazolines Using DAST via Beckmann Rearrangement

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