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Homogeneous Catalysis. Mechanisms of Metal Catalysed Claisen Rearrangements of O‐allylic‐S‐methyl dithiocarbonates
Author(s) -
Auburn P.R.,
Whelan J.,
Bosnich B.
Publication year - 1986
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198600037
Subject(s) - chemistry , catalysis , allylic rearrangement , claisen rearrangement , carbocation , medicinal chemistry , metal , sigmatropic reaction , stereochemistry , organic chemistry
A number of catalysts of Pd(II), Pt (II), Rh (I) and Ir(I) induce rearrangements of O‐allylic‐S‐methyl dithiocarbonates at 25° C. For most substrates, the Pd(II) and Pt(II) catalysts cause [3,3] sigmatropic (Claisen) rearrangements but the Rh(I) and Ir(I) catalysts give, in addition, other products depending on the catalyst and the substrate. The Claisen rearrangements observed with the Pd(II) and Pt(II) catalysts are believed to occur by a cyclization induced mechanism, whereas those rearrangements associated with the Rh(I) and Ir(I) catalysts, as well as in one case with the Pd(II) catalyst, appear to involve metal stabilized carbocation intermediates. When cyclic substrates are used retention of configuration is observed predominantly for all catalysts tried.