Diphenylamido Precursors to Bisalkoxide Molybdenum Olefin Metathesis Catalysts

Publisher Website
Google Scholar
Abstract
We have found that Mo(NAr)(CHR‘)(NPh2)2 (R‘ = t-Bu or CMe2Ph) and Mo(NAr‘)(CHCMe2Ph)(NPh2)2 (Ar = 2,6-i-Pr2C6H3; Ar‘ = 2,6-Me2C6H3) can be prepared through addition of 2 equiv of LiNPh2 to Mo(NR‘ ‘)(CHR‘)(OTf)2(dme) species (R‘ ‘ = Ar or Ar‘, dme = 1,2-dimethoxyethane), although yields are low. A high-yield route consists of addition of LiNPh2 to bishexafluro-tert-butoxide species. An X-ray structure of Mo(NAr)(CHCMe2Ph)(NPh2)2 reveals that the two diphenylamido groups are oriented in a manner that allows an 18-electron count to be achieved. The diphenylamido complexes react readily with t-BuOH and (CF3)2MeCOH, but not readily with the sterically demanding biphenol H2[Biphen] (Biphen2- = 3,3‘-di-tert-butyl-5,5‘,6,6‘-tetramethyl-1,1‘-biphenyl-2,2‘-diolate). The diphenylamido complexes do react with various 3,3‘-disubstituted binaphthols to yield binaphtholate catalysts that can be prepared in situ and employed for a simple asymmetric ring-closing metathesis reaction. In several cases conversions and enantioselectivities were comparable to reactions in which isolated catalysts were employed.

This publication has 28 references indexed in Scilit: