Zdilla Michael J, Abu-Omar Mahdi M
Brown Laboratory, Department of Chemistry, Purdue University, 560 Oval Drive,West Lafayette, IN 47907, USA.
J Am Chem Soc. 2006 Dec 27;128(51):16971-9. doi: 10.1021/ja0665489.
The reaction of Arl=NTs (Ar = 2-(tert-butylsulfonyl)benzene and Ts = p-toluenesulfonyl) and (tpfc)Mn (tpfc=5,10,15-tris(pentafluorophenyl)corrole), 1, affords the high-valent (tpfc)MnV=NTs, 2, on stopped-flow time scale. The reaction proceeds via the adduct [(tpfc)MnIII(ArINTs)], 3, with formation constant K3 = (10 +/- 2) x 10(3) L mol-1. Subsequently, 3 undergoes unimolecular group transfer to give complex 2 with the rate constant k4 = 0.26 +/- 0.07 s-1 at 24.0 degrees C. The complex (tpfc)Mn catalyzes [NTs] group transfer from ArINTs to styrene substrates with low catalyst loading and without requirement of excess olefin. The catalytic aziridination reaction is most efficient in benzene because solvents such as toluene undergo a competing hydrogen atom transfer (HAT) reaction resulting in H2NTs and lowered aziridine yields. The high-valent manganese imido complex (tpfc)Mn=NTs does not transfer its [NTs] group to styrene. Double-labeling experiments with ArINTs and ArINTstBu (TstBu = (p-tert-butylphenyl)sulfonyl) establish the source of [NR] transfer as a "third oxidant", which is an adduct of Mn(V) imido, (tpfc)Mn(NTstBu)(ArINTs). Formation of this oxidant is rate limiting in catalysis.
Arl=NTs（Ar = 2-(叔丁基磺酰基)苯，Ts = 对甲苯磺酰基）与(tpfc)Mn（tpfc = 5,10,15-三(五氟苯基)卟啉）反应，在停流时间尺度上生成高价态的(tpfc)MnV=NTs（2）。该反应通过加合物[(tpfc)MnIII(ArINTs)]（3）进行，形成常数K3 = (10 ± 2)×10³ L·mol⁻¹。随后，3发生单分子基团转移生成配合物2，在24.0℃时速率常数k4 = 0.26 ± 0.07 s⁻¹。配合物(tpfc)Mn以低催化剂负载量催化[NTs]基团从ArINTs转移至苯乙烯底物，且无需过量烯烃。催化氮杂环丙烷化反应在苯中最为高效，因为甲苯等溶剂会发生竞争性氢原子转移（HAT）反应，生成H2NTs并降低氮杂环丙烷产率。高价态锰亚胺配合物(tpfc)Mn=NTs不会将其[NTs]基团转移至苯乙烯。用ArINTs和ArINTstBu（TstBu = (对叔丁基苯基)磺酰基）进行的双标记实验确定了[NR]转移的来源为“第三种氧化剂”，即Mn(V)亚胺的加合物[(tpfc)Mn(NTstBu)(ArINTs)]（4）。这种氧化剂的形成是催化反应中的速率限制步骤。
