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Organische Synthesen mit Übergangsmetallkomplexen, 46. Alkenylcarben‐Chrom‐ und ‐Wolframkomplexe; Protonierung und Aktivierung durch Elektronen‐ziehende Substituenten
Author(s) -
Aumann Rudolf,
Hinterding Peter,
Krüger Carl,
Betz Peter
Publication year - 1990
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.19901230916
Subject(s) - chemistry , carbene , protonation , cationic polymerization , reactivity (psychology) , medicinal chemistry , chromium , ligand (biochemistry) , stereochemistry , ether , polar effect , polymer chemistry , catalysis , organic chemistry , medicine , ion , biochemistry , alternative medicine , receptor , pathology
Organic Syntheses via Transition Metal Complexes, 46. — Alkenylcarbene Chromium and Tungsten Complexes; Proton Addition and Activation by Electron‐Withdrawing Substituents Alkenylcarbene complexes L n MC(OEt)‐CHC(R)NMe 2 [ 1 , L n M Cr(CO) 5 , W(CO) 5 ; R H, CH 3 , C 6 H 5 ] add HBF 4 in ether to give novel cationic carbene complexes [L n MC(OEt)‐CH 2 ‐C(R)NMe 2 ]BF 4 ( 3 ) by protonation at C‐2 of the C‐CC ligand. The addition of HBF 4 to 7 leads to the formation of the cyclic carbene complexes 8 . Structures of 3 and 8 are assigned spectroscopically. X‐ray data are reported for 8a . Protonation of 1 and 7 results in a strong deshielding of the carbene carbon atoms, which parallels an increase of reactivity at the MC bonds. An activation of the MC bond has also been achieved by electron‐withdrawing substituents like N ‐acyl groups. We report on the first synthesis of [β‐(acylamino)‐alkenyl]carbene complexes 13 , which are more reactive than β‐(aminoalkenyl)carbene complexes 7 .