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The Tandem Pauson‐Khand Reaction
Author(s) -
Thommen Marc,
Veretenov Andrei L.,
GuidettiGrept Régine,
Keese Reinhart
Publication year - 1996
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19960790214
Subject(s) - chemistry , pauson–khand reaction , tandem , stereochemistry , aerospace engineering , intramolecular force , engineering
The conditions for the novel tandem Pauson‐Khand reaction have been explored. The highly functionalized tetracyclic compounds 11c, 11d , and 16 were prepared from the ene‐diynes 4c, 4d , and 10 by treatment with 2 equiv. of [Co 2 (CO) 8 ] and 4‐methylmorpholine N ‐oxide (NMO) or Me 3 NO in yields of 24, 22, and 53%, respectively ( Table ). In the presence of 1–3 equiv. of H 2 O added to the NMO used for induction of the Pauson‐Khand reaction of 6d , a mixture of cyclopentanones 17/18 and cyclopentenones 12/13 was obtained ( Scheme 5 ). The first example of a [Co 2 (CO) 6 ]‐induced highly stereoselective ene reaction is described. To account for these results, the formation of intermediates are proposed ( Schemes 6 and 7 ) which hitherto have not been considered in the mechanistic description of the Pauson‐Khand reaction.