Abstract
The ruthenabicyclic complex RuCl((R)- daipena)((R)-dm-segphos) with potassium tert-but- oxide catalyzes the hydrogenation of 2-alkylqui- noxalines and a 3-methyl-2H-1,4-benzoxazine in tol- uene under 20-100 atm of hydrogen at 408 Ct o afford S-configured cyclic amino products in greater than 97% enantiomeric excess {DAIPENA = anion of DAIPEN at the 2-position of an anisyl group, DAIPEN = 1,1-diApropyl-1,2-ethylene- diamine, DM-SEGPHOS = (4,4'-bi-1,3-benzodiox- ole)-5,5'-diylbis(di(3,5-xylyl)phosphine)}. The high catalytic activity results in a turnover number as high as 9400. Hydrogenation of the benzoimine het- erocycles with the RuCl((R)-daipena)((R)-segphos)/ potassium tert-butoxide system yields the R-config- ured products in high enantiomeric excess A=(4,4'-bi-1,3-benzodioxole)-5,5'-diylbis- Ane)). The mode of enantioselec- tion is discussed based on transition state models in- volving six-membered pericyclic structures.
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