H. Rudler et al., A major breakthrough in the use of alkoxycarbene complexes of chromium andtungsten for the synthesis of elaborate organic compounds: Dihydropyridineinduced reductions and cascade insertion reactions, TETRAHEDRON, 56(28), 2000, pp. 5001-5027
Alkoxy (alkyl)carbene complexes of tungsten and chromium react with dihydro
pyridine and N-methyldihydropyridine to give respectively pyridinium ylid c
omplexes and N-methylpyridinium tungstates and chromates. These two types o
f complexes can be used, for the former, as cyclopropanation reagents, for
the latter, as unprecedented initiators of cascade multiinsertions of olefi
ns, alkynes and CO. These insertions lead to elaborate polycyclic compounds
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