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Organomolybdän‐ und Organowolfram‐;Reagenzien, III. Chemoselektive, nichtbasische Carbonylmethylenierungs‐;Reagenzien aus MoOCl 3 (THF) 2 und MoOCl 4 : Bildung, Thermolabilität, Struktur
Author(s) -
Kauffmann Thomas,
Fiegenbaum Petra,
Papenberg Michael,
Wieschollek Raphael,
Wingbermühle Dorothea
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260114
Subject(s) - chemistry , methyllithium , reagent , molybdenum , cyclobutane , medicinal chemistry , methylene , bicyclic molecule , selectivity , stereochemistry , organic chemistry , catalysis , ring (chemistry)
Organomolybdenum and Organotungsten Reagents, III. — Selective, Nonbasic Carbonylmethylenation Reagents from MoOCl 3 (THF) 2 and MoOCl 4 : Formation, Thermolability, Structure From the family of more than 20 carbonylolefinating μ‐methylene molybdenum and tungsten complexes [1,2] the reagent “3”, obtained in solution by treatment of MoOCl 3 (THF) 2 with two equivalents of methyllithium, is probably the most favorable one for chemoselective carbonylolefination reactions. As judged by the 13 C‐ and 1 H‐NMR spectra the reagent is not a single species, but a mixture of either isomeric 1,3‐dioxo‐1,3‐dimolybda(V)cyclobutane complexes 3 , differing in the position of the ligands Cl, O, and THF at the molybdenum atoms, or of oligomers of 3 . — Treatment of MoOCl 4 with two equivalents of methyllithium gave a carbonylolefinating reagent “4” which, according to NMR data, consists of isomeric or oligomeric 1,3‐dioxo‐1,3‐dimolybda(VI)cyclobutane complexes 4 . Both reagents are labile at room temperature, but differ from the classical carbonylolefinating reagents by an acidic rather than a basic character, resistance to hydroxy groups, and high selectivity.