Berkowitz David B, Shen Weijun, Maiti Gourhari
Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304.
Tetrahedron Asymmetry. 2004 Sep 20;15(18):2845-2851. doi: 10.1016/j.tetasy.2004.06.052. Epub 2004 Sep 13.
An in situ enzymatic screening (ISES) approach to rapid catalyst evaluation recently pointed to Ni(0) as a new candidate transition metal for intramolecular allylic amination. This led to further exploration of chiral bidentate phosphine ligands for such transformations. Herein, a variety of P,N-ligands are examined for this Ni(0)-chemistry, using a model reaction leading into the vinylglycinol scaffold. On the one hand, an ,-bis(2-diphenylphosphinoethyl)alkylamine ('PNP') ligand proved to be the fastest ligand yet seen for this Ni(0)-transformation. On the other, phosphinooxazoline (PHOX) ligands of the Pfaltz-Helmchen-Williams variety gave the highest enantioselectivities (up to 51% ee) among P,N-ligands examined.
一种用于快速评估催化剂的原位酶促筛选（ISES）方法最近指出，Ni(0)是分子内烯丙基胺化反应的一种新型过渡金属候选物。这促使人们进一步探索用于此类转化的手性双齿膦配体。在此，使用导向乙烯基甘醇支架的模型反应，对多种P,N配体进行了此类Ni(0)化学研究。一方面，一种α,ω-双（2-二苯基膦基乙基）烷基胺（“PNP”）配体被证明是迄今为止该Ni(0)转化反应中反应速度最快的配体。另一方面，在所研究的P,N配体中，Pfaltz-Helmchen-Williams类型的膦基恶唑啉（PHOX）配体给出了最高的对映选择性（高达51% ee）。
