Synthesis Of Alkynes,Haloalkynes,Cyanoalkynes From Alkynols And Derivatization Of Cyanoalkynes

Alkynes are an important functional group in organic synthesis,which widely exist in natural products,pesticides,pharmaceuticals and organic polymers.In addition,alkynes-containing organic small molecules can be used as alkyne source,which play an important role in the construction of more complex organic compounds.In this thesis,a series of alkynyl compounds,such as alkynes,haloalkynes,cyanoalkynes and several derivatives of cyanoalkynes,are synthesized from 2-methylbut-3-yn-2-ol,which is relatively cheap and stable with water and oxygen as the origin of alkynes,and their structures and properties are characterized and studied preliminarily.The first chapter introduced the background knowledge and briefly introduces the existence and application of alkynes,haloalkynes,cyanoalkynes and derivatives of cyanoalkynes in nature and production research,and summarized the existing synthesis methods for haloalkynes and cyanoalkynes.The second chapter contained two aspects.On the one hand,a method for synthesizing terminal alkynes from alkynols was introduced.Based on 2-methylbut-3-yn-2-ol,alkynols were synthesized through Sonogashira coupling reaction,and then,in the 1,4-dioxane,they could remove the acetone protecting group to obtain terminal alkynes under relatively mild conditions.On the other hand,palladium-catalyzed deprotection cross-coupling of alkynols and benzyl carbonates was achieved in the presence of potassium carbonate.The third chapter introduced the method of preparation of iodoalkynes,bromoalkynes and chloroalkynes from terminal alkynes by the nano Ag particle supported on g-C₃N₄ to catalyze the terminal alkyne to prepare alkyne.For the first time,the iodoalkynes,bromoalkynes and chloroalkynes were achieved under the same catalytic system.The catalyst could be reused by simple centrifugation and reduction,and no significant decrease was found after 5 cycles of utilization in catalytic activity.The ICP-MS detection found that the single-catalyst Ag loss was less than 0.0128%.In the fourth chapter,the preparation of cyanoalkynes from bromoalkynes was introduced.It was found that brominated and iodo inorganic salts could effectively inhibit the formation of by-products,increasing the yield of cyanoalkynes.Thirty cyanoalkynes were successfully synthesized.This method was concise and straightforward,and has good compatibility with functional groups,so it has important synthetic significance.In the fifth chapter,the derivatization of cyanoalkynes was studied.According to the different conversion modes of the allyl-palladium intermediates,this part of the study included three aspects:1.Addition of halogen anions and cyanoalkynes to give stereoselective（Z）-β-haloacrylonitriles.2.Palladium-catalyzed addition of allyl halides with cyanoalkynes,controlled Z/E synthesis of 1-halo-1,4-dienenitriles with different additives.3.Palladium catalyzed addition reaction of acrolein and cyanoalkynes,and obtained stereoselective（Z）-4-enyl-1-pentanal products.