REGIOSELECTIVE OXYFUNCTIONALIZATION OF UNACTIVATED TERTIARY AND SECONDARY C-H BONDS OF ALKYLAMINES BY METHYL(TRIFLUOROMETHYL)DIOXIRANE IN ACID-MEDIUM
REGIOSELECTIVE OXYFUNCTIONALIZATION OF UNACTIVATED TERTIARY AND SECONDARY C-H BONDS OF ALKYLAMINES BY METHYL(TRIFLUOROMETHYL)DIOXIRANE IN ACID-MEDIUM
复制标题
DOI：
10.1021/ja00069a025
复制
发表时间：
1993-08-11
影响因子：
15
通讯作者：
ADAM, W
中科院分区：
文献类型：
--
作者：
ASENSIO, G;GONZALEZNUNEZ, ME;ADAM, W
伯烷基胺、仲烷基胺和叔烷基胺的四氟硼酸盐耐受甲基(三氟甲基)二氧六环(1b)的N氧化，这允许烷基侧链中脂肪族的叔基和次级C-H键的选择性氧化。在0℃下，用甲基(三氟甲基)-二氧六环(1b)的无酮溶液在二氯甲烷中进行氧化。通过这个过程，在3h内，无环胺、环胺和多环胺2a-e的三级C-H键被羟化，得到相应的氨基醇3a-e。对于无环胺2a，b，需要较长的反应时间，在强酸性介质中，通过与乙腈的Ritter反应得到相应的氨基乙酰胺4a，b。氨基的强吸电子性质甚至会使α和β位置上的叔基C-H键的氧化失活。直链脂肪族伯胺2f-h的次级C-H键在相应的氨基酮分子内缩合5f-h后，仅在epsilon位置氧化得到2，3，4，5-四氢-6-烷基吡啶6f-h。
Tetrafluoroborate salts of primary, secondary, and tertiary alkylamines are resistant toward N oxidation by methyl(trifluoromethyl)dioxirane (1b), which allows the selective oxidation of aliphatic tertiary and secondary C-H bonds in the alkyl side chain. The oxidations are carried out at 0-degrees-C with a ketone-free solution of methyl(trifluoromethyl)-dioxirane (1b) in methylene chloride. By this procedure, within 3 h the tertiary C-H bonds of acyclic, cyclic, and polycyclic amines 2a-e are hydroxylated to give the corresponding amino alcohols 3a-e. In the case of the acyclic amines 2a,b longer reaction times were necessary, and in the strong acid medium the corresponding amino acetamides 4a,b were obtained through Ritter reaction with the solvent acetonitrile. The strong electron-withdrawing nature of the ammonium group deactivates the oxidation of even tertiary C-H bonds at the alpha and beta positions. Secondary C-H bonds of the linear aliphatic primary amines 2f-h were oxidized exclusively at the epsilon position to give the 2,3,4,5-tetrahydro-6-alkylpyridines 6f-h after intramolecular condensation of the corresponding amino ketones 5f-h.