Abstract Alcohols and phenols are tetrahydropyranylated rapidly in high yields in the presence of lithium bromide and dichloromethane at room temperature. Deprotection of these THP ethers can also be effected readily by mere change of the solvent to methanol and refluxing with excess lithium bromide. Due to neutral reaction conditions employed, the method is also compatible with compounds having acid
Reaction of Tetrahydropyranyl Ethers with Triethylsilyl Trifluoromethanesulfonate–2,4,6-Collidine Combination: Speculation on the Intermediate, Efficient Deprotection, and Application to Efficient Ring-Closing Metathesis as a Tether
作者:Hiromichi Fujioka、Takashi Okitsu、Takuya Ohnaka、Yoshinari Sawama、Ozora Kubo、Kazuhisa Okamoto、Yasuyuki Kita
DOI:10.1002/adsc.200600572
日期:2007.3.5
chemoselective deprotection method of THP ethers. The characteristic feature of the reaction is that the reaction conditions are weakly basic. Then, the reaction can proceed without affecting acid-labile protecting groups. Furthermore, the intermediates from alkenol–THP ether were trapped with other alkenols to give acyclic mixed acetals, which were subjected to efficient ring-closing metathesis by using the
四氢吡喃基(THP)醚与三乙基甲硅烷基三氟甲磺酸盐(TESOTf)–2,4,6-可力丁的反应通过胶体盐中间体进行,以高收率得到了醇和4-三乙基甲硅烷氧基丁醛。中间体的结构由1确定1 H NMR和FAB-MS研究并通过用EtOH捕获。该反应用于THP醚的温和,高效和高度化学选择性的脱保护方法。该反应的特征是反应条件是弱碱性的。然后,可以在不影响酸不稳定的保护基的情况下进行反应。此外,将烯醇-THP醚的中间体与其他烯醇截留,得到无环的混合缩醛,然后以四氢吡喃基单元为系绳,进行有效的闭环复分解。
Transformation of tetrahydropyranyl ether of allylic alcohol into 7-octene-1,5-diol by means of trialkylmanganate
Treatment of tetrahydropyranyl (or tetrahydrofuranyl) ether of allylic alcohol with tributylmanganate provided 7-octene-1,5-diol (or 6-hepten-1,4-diol) in good yields. The reaction of propargylic tetrahydropyranyl ether with tributylmanganate is also described.