| Abstract
| - Bisdiphenylamido complexes of the type Mo(NR‘ ‘)(CHR‘)(NPh2)2 (R‘ = t-Bu or CMe2Ph, R‘ ‘ = 2,6-i-Pr2C6H3 or 2,6-Me2C6H3) have been prepared and found to react readily with various enantiomerically pure 3,3‘-disubstituted binaphthols to yield binaphtholate catalysts in situ. Catalysts prepared in situ have been employed for a simple asymmetric ring-closing reaction with conversions and enantioselectivities comparable to reactions in which isolated catalysts were employed.
- 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 LiNPh2to Mo(NR‘ ‘)(CHR‘)(OTf)2(dme) species (R‘ ‘ = Ar or Ar‘, dme = 1,2-dimethoxyethane), although yields arelow. A high-yield route consists of addition of LiNPh2 to bishexafluro-tert-butoxide species. An X-raystructure of Mo(NAr)(CHCMe2Ph)(NPh2)2 reveals that the two diphenylamido groups are oriented in amanner that allows an 18-electron count to be achieved. The diphenylamido complexes react readily witht-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 doreact with various 3,3‘-disubstituted binaphthols to yield binaphtholate catalysts that can be prepared insitu and employed for a simple asymmetric ring-closing metathesis reaction. In several cases conversionsand enantioselectivities were comparable to reactions in which isolated catalysts were employed.
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