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Cycloadditionsreaktionen von Organometallkomplexen, XI. Cobalta‐Heterocyclen durch [2 + 3]‐Cycloaddition von α‐Ketocarbenen an Co‐CO‐ und Co‐ CNR‐Bindungen
Author(s) -
Strecker Beate,
Zeier Bernd,
Schulz Michael,
Wolf Justin,
Werner Helmut
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.19901230905
Subject(s) - chemistry , cycloaddition , cyclopentadienyl complex , stereochemistry , medicinal chemistry , diastereomer , catalysis , organic chemistry
Cycloaddition Reactions of Organometallic Complexes, XI. ‐ Cobaltaheterocycles by [2 + 3) Cycloaddition of α‐Keto Carbenes to Co ‐ CO and Co ‐ CNR Bonds The reactions of the carbonyl(cyclopentadienyl) and (cyclopentadienyl)isocyanidecobalt complexes C 5 H 5 Co(CO)(PR 3 ) ( 1 ‐ 4 ) and C 5 H 5 Co(CNR)(PMe 3 ) ( 5, 6 ) with α‐diazocarbonyl compounds R 1 C(O)C(N 2 )R 2 lead to the formation of the cobaltaheterocycles C 5 H 5 (PR 3 )(O) ( 7 ‐ 12 ) and C 5 H 5 (PMe 3 )(NR) ( 13 ‐ 16 ), respectively. For R (S)‐CH(Me)Ph a mixture of diastereoisomers R Co S Co S c is obtained. The complexes 13 ‐ 16 react with HBF 4 in ether to give the cations [C 5 H 5 (PMe 3 )‐(NHR)] + ( 17 ‐ 20 , with BF 4 as anion), which on treatment with base regenerate the uncharged cobaltaheterocycles. The X‐ray structural analysis of 19 ‐ R Co S c reveals the presence of a planar CoOC 3 five‐membered ring which presumably is formed by a [2+3] cycloaddition of an α‐ketocarbene to the CoCNR bond.