ausblenden:
Schlagwörter:
metal activation - McMurry reaction - macrocyclization - template effect - supported reagents - sodium
Zusammenfassung:
Sodium deposited on inorganic supports such as Al2O3, TiO2 and NaCl (‘high-surface sodium') is a cheap, readily prepared, nonpyrophoric reducing agent for TiCl3. The low-valent titanium thus obtained, after only 1 h reduction time, is well suited for McMurry coupling reactions, particularly of aromatic carbonyl compounds. It exhibits a previously unrivalled template effect for the cyclization of dicarbonyl compounds to (macrocyclic) cycloalkenes and is suitable for the reduction of N-acyl-2-aminobenzophenone derivatives to 2,3-disubstituted indoles. Even a 36-membered ring could be formed without recourse to high dilution techniques.
