E/Z) Equilibria. Part 16. Lone Electron Pair Donor Quality of the Imino Function: Synthesis and Reactivity of Sterically Strongly Congested Iminocyclopentanes.-Sterically strongly hindered Schiff bases are constructed in order to develop suitable isoelectronic and isosteric model substances for the non-observable carbanions of vinyllithium compounds. (V) is obtained by permethylation; it forms salts such as (VI) by N-protonation. The C= N double bond is strongly shielded against nucleophilic attack and cannot be hydrolyzed. Nitration (and bromination) occur in the aromatic ring showing strongly the directing power of the lone pair of the imino function. This π-donor quality is assessed by probing weaker electrophiles and qualitative competition experiments. -(KNORR, R.; HINTERMEYER-HILPERT, M.; MEHLSTAEUBL, J.; HOANG THI PHUNG; NEUNER, B.; BOEHRER, P.; Chem.

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Sterically Congested Molecules. Part 6. Lone Electron Pair Donor Quality of the Imino Function: Increased Front Strain and Electronic Substituent Effects on Sterically Accelerated Nitrogen Inversion in Iminocyclopentanes.-The p-substituents in (I) are modified without interfering reactions at the C=N double bond. For a quantification of the lone-pair donor quality of the imino function in the substituted series (Ib) and (Ic) ( total 13 examples) their activation parameters of stereomutation ( Hammett values) are invesigated. -(KNORR, R.; HOANG THI PHUNG; MEHLSTAEUBL, J.; HINTERMEYER-HILPERT, M.; LUEDEMANN, H.-D.; LANG, E.; SEXTL, G.; RATTAY, W.; BOEHRER, P.; Chem. Ber. 126 (1993) 1, 217-224; Inst. Org. Chem., Univ.

1992 magnetic resonance, nuclear quadrupole resonance magnetic resonance, nuclear quadrupole resonance (organic substances) K 2560 50 -049 (E,Z) Equilibria. Part 15. Syntheses and Lability of the Configuration of 2-Iminoindan Derivatives with Front Strain -(NMR spectroscopic investigations of the (E,Z) configurational diastereotopomerization of a variety of sterically shielded 2-iminoindans). -(KNORR, R.; FERCHLAND, K.; MEHLSTAEUBL, J.; THI PHUNG HOANG; BOEHRER, P.; LUEDEMANN, H.-D.; LANG, E.; Chem.

091ChemInform Abstract α-Peralkylation of (I) proceeds in the stable mixture of NaH/Me2SO4 when (I) is added at 20 rc C. Ethylation of the indanone (IV) is carried out by simultaneous addition of ketone and reagent at temp. below 31 rc C.