作者:Ana-Florina Voica、Abraham Mendoza、Will R. Gutekunst、Jorge Otero Fraga、Phil S. Baran
DOI:10.1038/nchem.1385
日期:2012.8
The excision of hydrogen from an aliphatic carbon chain to produce an isolated olefin (desaturation) without overoxidation is one of the most impressive and powerful biosynthetic transformations for which there are no simple and mild laboratory substitutes. The versatility of olefins and the range of reactions they undergo are unsurpassed in functional group space. Thus, the conversion of a relatively inert aliphatic system into its unsaturated counterpart could open new possibilities in retrosynthesis. In this article, the invention of a directing group to achieve such a transformation under mild, operationally simple, metal-free conditions is outlined. This âportable desaturaseâ (TzoCl) is a bench-stable, commercial entity (Aldrich, catalogue number L510092) that is facile to install on alcohol and amine functionalities to ultimately effect remote desaturation, while leaving behind a synthetically useful tosyl group. A bench-stable, aryl sulfonyl triazene is described that can be appended to alcohols or amines and used as a directing group to effect remote desaturation of unactivated aliphatics to produce olefins. The reaction is mild, operationally simple, requires no added metals and produces unsaturated tosylates or tosylamides available for further functionalization.
从脂肪碳链中切除氢以产生孤立的烯烃(脱氢),而不发生过氧化,是一种非常令人印象深刻和强大的生物合成转化,目前尚无简单温和的实验室替代方法。烯烃的多功能性及其经历的反应范围在官能团空间中是无与伦比的。因此,将相对惰性的脂肪族体系转化为其不饱和对应物,可能为逆合成开辟新的可能性。本文概述了一种引导基团的发明,以在温和、操作简单、无金属的条件下实现此类转化。这种“可携式脱氢酶”(TzoCl)是一种在桌面上稳定的商业实体(阿尔德里奇,目录编号L510092),易于在醇和胺功能上安装,最终实现远程脱氢,同时保留一个合成上有用的托烯基(tosyl)基团。文中描述了一种稳定的芳基磺酰三氮唑,可以附加到醇或胺上,作为引导基团实现非活化脂肪族化合物的远程脱氢,以产生烯烃。这一反应温和,操作简单,不需额外添加金属,产生可用于进一步功能化的不饱和托烯基化合物或托烯胺。