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Organische Synthesen mit Übergangsmetallkomplexen, 48. Methyl(thiocarben)‐ und Alkenyl(thiocarben)‐Chrom‐Komplexe: Darstellung und Reaktionen
Author(s) -
Aumann Rudolf,
Schröder Jochen
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.19901231017
Subject(s) - chemistry , chromium , medicinal chemistry , ether , methanol , aldol condensation , catalysis , isocyanide , thioester , reactivity (psychology) , transition metal , polymer chemistry , organic chemistry , medicine , alternative medicine , pathology , enzyme
Organic Syntheses via Transition Metal Complexes, 48. — Methyl Thiocarbene and Alkenyl Thiocarbene Chromium Complexes: Synthesis and Reactions Thiocarbene chromium complexes (CO) 5 CrC(SR 1 )R ( 4 : R Me, Ph; R 1 c‐C 6 H 11 , CH 2 CHCH 2 , C 2 H 5 , C 6 H 5 ) were readily obtained in up to 97% isolated yields from the corresponding ethoxycarbene chromium complexes 5a, b and thiols 6 in methanol in the presence of Na 2 CO 3 as a catalyst. Reaction conditions, which lead to unfavorable side products, like thioacetals 8 and or thioenol ether 10 , are discussed. Methyl thiocarbene complexes 4b–d undergo a facile aldol condensation with the aromatic aldehydes 14 or 16 to give alkenyl thiocarbene complexes 15b–d and 17 , respectively. The CrC bonds of 15 prove to be reactive towards the insertion of isocyanides or oxygen. Thus, on addition of two equivalents of the isocyanide 18 to 15d , 1‐aza‐1,2,4‐pentatriene 20 is obtained. The oxidative decomposition of 15d on silica gel leads to the formation of thioester 25 and thioindene 26 . Characteristic differences in the reactivity of thiocarbene complexes and ethoxycarbene complexes are discussed.