Intramolecular 1,2-alkyl shifts in unsymmetric dialkoxycarbenes studied by very low vapour pressure (VLVP) pyroiysis – mass spectrometry
作者:Dennis Suh、David L. Pole、John Warkentin、Johan K. Terlouw
DOI:10.1139/v96-059
日期:1996.4.1
time scale of the experiment. Very low vapour pressure (VLVP) pyrolysis - mass spectrometry of I in conjunction with (multiple) collision experiments shows that 1 completely isomerizes, via a 1,2-trifluoroethyl shift, into methyl 3,3,3-trifluoropropionate, CF,CH,C(=O)OCH,, la. This technique was also used to study the related dialkoxycarbenes C,H,O-C-OCH,CF,, 2, CH,O-C-0C2H,, 3, and CH,O-C-OCH(CH,)
由相应的 2,2-二烷氧基-5,5-二甲基-A3-1,3,4-恶二唑啉生成。热解生成的卡宾 2 的行为类似于 1,并完全异构化为 3,3,3-三氟丙酸乙酯,2a。中性卡宾 3 和 4 仅通过 1,2-烷基转移发生部分异构化,其中乙基和异丙基分别显示出略大于甲基的迁移能力。迁移能力的差异用类似于卡宾中 1,2-H 转变的过渡态模型来解释,在迁移组中产生负电荷。CF,CH, 与 CH 和 CH,CH2 相比具有更大的迁移能力,