藉由磺醯化試劑進行α-Hydroxy ketoximes與α-Oxo ketoximes的Beckmann裂解反應

Abstract

本論文原先預期以benzoin oxime利用磺醯化試劑活化N-OH鍵後進行分子內合環反應，得到indole產物。但卻意外得到Beckmann fragmentation的產物。為探討此反應的應用性，在我們的研究中是利用benzaldehyde系列化合物先與氰化鈉進行benzoin condensation後，產生benzoin衍生物, 同時也可以將benzoin進行氧化形成benzil的衍生物。將benzoin和benzil的衍生物分別與hydroxylamine hydrochloride進行反應，形成ketoxime後，最後在Ts2O或p-NsCl的反應條件下，進行Beckmann fragmentation得到碳–碳鍵裂解的產物。

Our original goal was to use sulfonylating reagents to activate the N-OH bond cleavage of benzoin oxime to undergo intramolecular cyclization. However, this reaction gave only the C-C bond cleavage adducts via Beckmann fragmentation to form a mixture of nitrile and aldehyde. Therefore, our investigation focused on the synthetic application of this fragmentation reaction. The substrates were prepared from a series of benzaldehyde compounds with sodium cyanide to undergo benzoin condensation to form benzoin derivatives. Benzoins were further oxidized to form benzil derivatives. Both compounds were reacted with hydroxylamine hydrochloride to form the corresponding ketoximes. The ketoximes were treated with p-toluenesulfonic anhydride or p-nitrobenzenesulfonyl chloride to undergo Beckmann fragmentation to afford a mixture of C-C bond cleavaged adducts.