(R)-bis-Binaphthoxy iodo lanthanides as catalysts for Diels–Alder reactions
摘要:
[(R)-1,1'bi-2,2'-Naphthoxy]LnI(THF)(2) (Ln: Yb, Sm, La) 5 have been prepared by reaction of the bispotassium salt. of (R)-binaphthol with lanthanide triiodides, and characterized. They are active catalysts for Diels-Alder reactions although with low asymmetric inductions. The lanthanum iodo bisbinaphthoxide gives a slightly higher enantiomeric excess than the two other complexes. (C) 2003 Elsevier Science B.V. All rights reserved.
Reactions of lanthanide triiodides with potassium bistrimethylsilyl amide have been investigated. For lanthanum, recrystallisation from THF-toluene led to monocrystals of the dimeric bisamide [La(mu -I)N(TMS)(2))(2)(THF)](2). We have shown that samarium diiodide and lanthanide triiodides are efficient for lanthanum and samarium reactions, a mixture of tris amides and iodo bisamides is obtained, while only the latter compound is obtained for ytterbium. (C) 2001 Elsevier Science B.V. All rights reserved.