Chemoselective Oxidation of <i>p</i>-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
作者:Shohei Hamada、Koichi Sugimoto、Elghareeb E. Elboray、Takeo Kawabata、Takumi Furuta
DOI:10.1021/acs.orglett.0c01839
日期:2020.7.17
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxylradicalcatalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained
2-Naphthylmethoxymethyl as a Mildly Introducible and Oxidatively Removable Benzyloxymethyl-Type Protecting Group
作者:Takuya Sato、Tohru Oishi、Kohei Torikai
DOI:10.1021/acs.orglett.5b01408
日期:2015.6.19
(including phenolic hydroxy and carboxy) and mercapto groups. The NAPOM group can be introduced in extremely mild conditions (naphthylmethoxymethyl chloride, 2,6-lutidine, room temperature) without concomitant acyl migration in a 1,2-diol system. Furthermore, selective removal of NAPOM in the presence of naphthylmethyl (NAP) and p-methoxybenzyl (PMB) groups and, conversely, that of PMB in the presence of
High Efficiency Synthesis of F-18 Fluoromethyl Ethers: An Attractive Alternative for C-11 Methyl Groups in Positron Emission Tomography Radiopharmaceuticals
作者:Chansoo Park、Byoung Se Lee、Dae Yoon Chi
DOI:10.1021/ol401792n
日期:2013.9.6
A rapid and efficient method for the synthesis of O-fluoromethyl aliphatic and aromatic ethers is presented. This method is so mild that it can be used for the preparation of positron emission tomography (PET) radiopharmaceuticals bearing O-[18F]fluoromethyl groups.
The use of 2-O-alkoxymethyl groups as effective stereodirecting substituents for the construction of 1,2-trans glycosidic linkages is reported. The observed stereoselectivity arises from the intramolecular formation of a five-membered cyclic architecture between the 2-O-alkoxymethyl substituent and the oxocarbenium ion, which provides the expected facial selectivity. Furthermore, the observed stereocontrol
(2021). A New Julia-Kocienski Reagent for Convenient Access to the 2-Naphthylmethyl Vinyl Ethers. Organic Preparations and Procedures International: Vol. 53, No. 2, pp. 200-205.