Scrambling of Oxygen-18 during the “Borderline” Solvolysis of 1-(3-Nitrophenyl)ethyl Tosylate
作者:Yutaka Tsuji、Maria M. Toteva、Tina L. Amyes、John P. Richard
DOI:10.1021/ol0484409
日期:2004.9.1
[reaction: see text] There is substantial isomerization (kiso=0.32 x 10(-3) s(-1)) of 3-NO2C6H4(13)CH(Me)OS(18O)2Tos during solvolysis (ksolv=1.04 x 10(-3) s(-1)) in 50/50 trifluoroethanol/water, even though the estimated lifetime of the putative 1-(3-nitrophenyl)ethyl carbocation intermediate of solvolysis (ca. 10(-13) s(-1)) is too short to allow rearrangement that exchanges the positions of 16O
[反应:请参见文本]溶剂分解过程中3-NO2C6H4(13)CH(Me)OS(18O)2Tos发生了相当大的异构化(kiso = 0.32 x 10(-3)s(-1))(ksolv = 1.04 x 10 (-3)s(-1))在50/50三氟乙醇/水中,即使溶剂分解的估计的1-(3-硝基苯基)乙基碳正离子中间体的估计寿命(约10(-13)s(-1) ))太短,以至于无法进行重排以交换磺酸盐离去基团上16O和18O的位置。这表明异构化是通过避免形成碳阳离子-阴离子对中间体的机理进行的。