Electrospray ionization (ESI) fragmentations and dimethyldioxirane reactivities of three diverse lactams having full, half, and zero resonance energies.
Electrospray ionization (ESI) fragmentations and dimethyldioxirane reactivities of three diverse lactams having full, half, and zero resonance energies.
复制标题
具有全共振能量、半共振能量和零共振能量的三种不同内酰胺的电喷雾电离 (ESI) 裂解和二甲基二氧杂环己烷反应性。
DOI：
10.1021/jo402041u
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Greenberg,Arthur
中科院分区：
文献类型：
--
作者：
Morgan,KathleenM;Ashline,DavidJ;Morgan,JessicaP;Greenberg,Arthur
Three lactams having, respectively, ∼20, ∼10, and 0 kcal/mol of resonance energy have been subjected to electrospray ionization mass spectrometry (ESI/MS) as well as to attempted reaction with dimethyldioxirane (DMDO). The ESI/MS for all three lactams are consistent with fragmentation from the N-protonated, rather than the O-protonated tautomer. Each exhibits a unique fragmentation pathway. DFT calculations are employed to provide insights concerning these pathways.N-Ethyl-2-pyrrolidinone and 1-azabicyclo[3.3.1]nonan-2-one, the full- and half-resonance lactams, are unreactive with DMDO. The “Kirby lactam” (3,5,7-trimethyl-1-azaadamantan-2-one) has zero resonance energy and reacts rapidly with DMDO to generate a mixture of reaction products. The structure assigned to one of these is the 2,2-dihydroxy-N-oxide, thought to be stabilized by intramolecular hydrogen bonding and buttressing by the methyl substituents. A reasonable pathway to this derivative might involve formation of an extremely labileN-oxide, in a purely formal sense, an example of the hitherto-unknown amideN-oxides, followed by hydration with traces of moisture.
