A Rapid, Solvent-Free Deprotection of Methoxymethyl (MOM) Ethers by pTSA; An Eco-Friendly Approach
作者:Nanjan Pandurangan
DOI:10.2174/1570178614666170321103650
日期:2017.6.8
Background: Ease of preparation and alkaline stability of methoxymethyl (MOM) makes it
an important hydroxyl protecting group. A number of methods are available for the deprotection of
MOM. Though the methods are good in general, they use solvents, require prolonged reaction time
and tedious work up. A solvent free, solid phase, fast deprotection of MOM has been developed and is
the major theme of this paper.
Methods: A mixture of MOM protected compounds and pTSA is triturated in a mortar (5 min) and left
at room temperature for 30 min. On addition of water (4oC), pTSA, methanol and formaldehyde dissolved
leaving the products as precipitates.
Results: A series of different MOM ethers were deprotected by this method in good to excellent yield
(85-98%). The compatibility of MOM in the presence of other protections such as methoxyl, benzyl, ester,
amide, allyl and lactone was also established. Acetate protection is not stable under these conditions.
Conclusion: An efficient, selective and high yielding deprotection MOM groups by pTSA under solvent
free condition is described. The process is environment friendly since no solvent was used in the
deprotection process. The reaction conditions are mild and should be useful for the deprotection of
MOM derivatives of complex and labile molecules.
背景:甲氧基亚甲基(MOM)的制备简便和碱性稳定性使其成为一种重要的羟基保护基团。目前已有多种方法可用于去保护MOM。虽然这些方法一般较好,但它们使用溶剂,需要较长的反应时间和繁琐的后处理。本文的主要主题是研发了一种无溶剂、固相、快速去保护MOM的方法。
方法:将MOM保护的化合物与对甲苯磺酸(pTSA)混合,在研钵中研磨5分钟后静置30分钟。随后加入水(4°C),pTSA、甲醇和甲醛溶解,留下沉淀产品。
结果:通过此方法去保护的一系列不同的MOM醚均获得良好到优异的产率(85-98%)。还确定了MOM在其他保护基团(如甲氧基、苄基、酯、酰胺、烯丙基和内酯)存在下的兼容性。而醋酸保护在这些条件下并不稳定。
结论:描述了一种高效、选择性和高产率的去保护MOM基团的方法,该方法是在无溶剂条件下由pTSA完成。该过程环保,因为去保护过程中未使用溶剂。反应条件温和,应对复杂和易分解分子的MOM衍生物的去保护过程有益。