INTERACTION OF DIHYDROPYRIDINES WITH ALKOXYCARBENE COMPLEXES OF TUNGSTEN - FORMATION AND USE AS CYCLOPROPANATION REAGENTS OF PYRIDINIUM YLIDE COMPLEXES
B. Martinvaca et al., INTERACTION OF DIHYDROPYRIDINES WITH ALKOXYCARBENE COMPLEXES OF TUNGSTEN - FORMATION AND USE AS CYCLOPROPANATION REAGENTS OF PYRIDINIUM YLIDE COMPLEXES, Journal of organometallic chemistry, 567(1-2), 1998, pp. 119-126
Alkoxycarbene complexes of tungsten, e.g. (CO)(5)W=C(CH3)OEt (13) reac
t with 1,2- and 1,4-dihydropyridines, to give, upon transfer of a hydr
ide to the carbene carbon, elimination of ethanol, and readdition of p
yridine to an unstable alkylidene complex (CO)(5)W=C(H)CH3 (22), pyrid
inium ylide complexes of the type (CO)(5)W--C(H)(CH3)Py+ (17). A secon
d pyridinium ylide complex (CO)(5)W-C(H)(CH3)C5H7N (16), and a third d
ihydropyridinium complex (CO)(5)W-C(H)(CH3)C8H11N (15), resulting from
the interaction of respectively 2,5-dihydropyridine and 5-isopropylid
ene-2,5-dihydropyridine with (CO)(5)W=C(H)(CH3) were also isolated and
fully characterized by X-ray crystallography. The origin of the two l
atter complexes could be established. The new N-ylide complexes react
with olefins to give cyclopropanes. Especially interesting, as far as
the yields are concerned, is the interaction of highly nucleophilic ol
efins such as enamines with (CO)(5)W--C(H)PhPy+ (25) which leads to is
omeric cyclopropylamines. The mechanism of their formation will be dis
cussed. (C) 1998 Elsevier Science S.A. All rights reserved.