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DOI: 10.1055/sos-SD-046-00090

Gandon, V.; Thorimbert, S.; Malacria, M.Science of Synthesis, (200946201.

Only a few methods have been reported for the formation of cyclohexa-1,3-dienes by means of iridium-catalyzed [2+2+2] cycloadditions. Nevertheless, these reactions are efficient, even when carried out at very low catalyst loadings, especially for cocyclizations between 1,6-enynes 95 and alkynes to afford bicyclic dienes 96 (Scheme 34).[‌78‌] However, byproducts 97 and 98, resulting from the formal metathesis of the enyne, are to be expected and the extent of this competition depends upon the type of diphosphine ligand present in the catalyst. Thus, with the 1,1-bis(diphenylphosphino)ferrocene ligand enyne metathesis prevails, whereas with 1,2-bis(diphenylphosphino)ethane cycloaddition may predominate.

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Meeeeeeeeee 88

M8 M8 Meeeee Meee (e) Meeee (%)
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Meeee [(M)-88/(M)-88/(M)-88)] Meeee (%)
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M Me eeee 8 88 88 eeee 8 [‌88‌]
M Me eeee 8 88 88:8:8 88 [‌88‌]
M Me eeee 88 88 88 eeee 88 [‌88‌]
M Me eeee 8 8 88:8:8 88 [‌88‌]
M Me eeee 8 8 88:8:8 88 [‌88‌]
M Me eeee 8 88 88 eeee 88 [‌88‌]
M Me eeee 88 88 88 eeee 88 [‌88‌]
Me Me eeee 8 88 88:8:88 88 [‌88‌]
Me Me eeee 8 88 88:88:88 88 [‌88‌]

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Meeeee 88 Meeeeee-Meeeeeeee [8+8+8] Meeeeeeeeeeeee eeeeeee 8,8-Meeeee eee Meeeeee[‌888‌]

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