How advantageous is the intramolecular aggregation of 1,4-organodilithio compounds?
1,11-Dilithio-5,5,7,7-tetramethyl-5,7-dihydrodibenz[c,e]oxepin (3; shown as I) is a conformationally confined analog of o,o'-dilithiobiphenyl (1). A temp. variable NMR study of this model compd., monitoring the coalescence of its diastereotopic Me groups, has revealed a barrier of about 12 kcal/mol to planarization, just 2 kcal/mol less than that found with the metal-free heterocycle. Thus, the energetic benefit of intramol. aggregation of o,o'-dilithiobisaryls is significantly smaller than that predicted by ab initio calcns. [on SciFinder (R)]
Organometallic and Organometalloidal Compounds
Inst. Chim. Org.,Univ. Barre,Lausanne,Switz.
written in English.
156749-49-4P Role: PRP (Properties), PREP (Preparation) (generation and rotational barrier of, variable-temp. NMR in relation to); 156749-48-3 Role: RCT (Reactant), RACT (Reactant or reagent) (methylation of); 156749-47-2P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and cyclization of); 156749-50-7P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (prepn. and lithiation of); 6672-71-5P; 156749-51-8P; 156749-52-9P Role: SPN (Synthetic preparation), PREP (Preparation) (prepn. of)
Record created on 2006-03-03, modified on 2016-08-08