Molecular rearrangements metathesis reactions

An outstanding example of a branching pathway exploited complementary cyclisation reactions to yield alternative molecular scaffolds (Scheme 1.5). A four-component Petasis condensation reaction was used to assemble flexible cyclisation precursors e.g. 14). Alternative cyclisation reactions were then used to yield products with distinct molecular scaffolds Pd-catalysed cyclisation (- 15a) enyne metathesis (- 15b) Ru-catalysed cycloheptatriene formation (- 15c) Au-catalysed cyclisation of the alcohol onto the alkyne (- 15d) base-induced cyclisation (- 15e) Pauson-Khand reaction 15f) and Miesenheimer [ 2,3]-sigmatropic rearrangement (not shown). Four of these cyclisation reactions could be used again to convert the enyne 15e into molecules with four further scaffolds (17a-d). In addition, Diels Alder reactions with 4-methyl-l,2,4-triazoline-3,5-dione converted the dienes 15b, 17a and 17d... 

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