氧化?的製備及其與三乙基硼之反應

The Synthesis of Nitrile Oxide and its reaction with triethylborane

方惠玉(Hui-Yu Fang)

指導教授 ： 姚清發

國立臺灣師範大學/理學院/化學系/碩士(2000年)

摘要

中文摘要
β-nitrostyrene系列與穩定的親核試劑反應後加入稀酸水溶液（5% HCl(aq)）水解後可得到1,4-加成的產物（硝基烷類）。如果將反應所形成之中間體nitronates 加入冰浴的濃鹽酸水溶液中，預期會進行Nef or Meyer反應得到羰基或羧酸的化合物。但分析實驗結果卻意外地發現氯離子可以捕捉住活潑的中間體而形成hydroximoyl chlorides。hydroximoyl chlorides 在鹼性條件下可脫去HCl 而形成nitrile oxides，隨即和烯或炔類進行1,3-dipolar cycloaddition反應而生成具有立體專一性或高度立體選擇性的產物2-isoxazolines或isoxazoles。若穩定性親核試劑具有不飽和鍵的，在1,4-加成反應(Michael addition)後用35% HCl(aq)及Et3N處理，可以進行分子內反應而產生5,5-環之環狀化合物或環醚類。
大部份的nitrile oxides在室溫下不能穩定存在，會在很短的時間內進行自身1,3-dipoalr cycloaddition形成furoxan。在過去的文獻發現有一些在α碳位置具有較大立體障礙的nitrile oxides，在室溫下能夠穩定存在，這一類的nitrile oxides可以和親核試劑進行加成反應。本實驗設計利用親核試劑與β-nitrostyrene系列反應產生的hydroximoyl chloride來合成有較大立體障礙的nitrile oxides，並利用Et3B在氧氣的催化下產生的乙基自由基對nitrile oxides進行親核加成反應，發現在較溫和的條件下，可以得高產率的產物oximes。

關鍵字

三乙基硼 ； 親核性加成反應

並列摘要

Abstract
β-nitrostyrenes can react with stablilzed nucleophiles to form 1,4-addition products such as primary nitroalkanes after workup with dilute aqueous acid solution. It is expected to undergo Nef or Meyer reaction to generate carbonyl compounds or carboxylic acids if the intermediate-nitronates are slowly added to the ice cold concentrated hydrochloric acid. Surprisingly, chloride ion can trap the reactive intermediates to generate hydroximoyl chlorides. Hydroximoyl chlorides can be converted into nitrile oxides by treating with base such as triethylamine. It is known that nitrile oxides undergo 1,3-dipolar cycloaddition with alkenes or alkynes to generate stereospecific or stereoselective product such as 2-isoxazolines or isoxazoles. One-pot synthesis of five-membered carbocycles or cyclic ether from the Michael addition of the stabilized nucleophiles with the β-nitrostyrenes is reported.
Most nitrile oxides will dimmerize to form furoxans. Some nitrile oxides that sterically hindrance at α carbon will be stable at the room temperature and can undergo nucleophilic addition with nucleophiles . We use the stable nitrile oxides undergo nucleophilic addition with ethyl radical that generated by triethylboran.

並列關鍵字

nitrile oxide ； triethylborane ； nucleophilic addition

參考文獻

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