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Please login to access the full content or check if you have access via Variation 3: Platinum- and Gold-Catalyzed Cycloisomerization To Give Vinylcycloalkenes

DOI: 10.1055/sos-SD-046-00090

Gandon, V.; Thorimbert, S.; Malacria, M.Science of Synthesis, (200946221.

During the course of investigations into palladium-catalyzed enyne metathesis it was reported that the use of diacetoxybis(triphenylphosphine)platinum associated with dimethyl acetylenedicarboxylate allows the production of vinylcyclopentenes,[‌149‌] and in 1996 it was shown that platinum(II), platinum(IV), and gold(III) chlorides can be employed for the skeletal reorganizations of 1,6- and 1,7-enynes to give 1-vinylcycloalkenes.[‌156‌] Other platinum complexes, such as dichlorobis(triphenylphosphine)platinum(II) or dichlo­ro(cyclooctadiene)platinum(II), have no catalytic activity in such procedures, which suggests that, although chloride is necessary, electron-rich ligands should be absent. Since this pioneering work was carried out, spectacular efforts have been made by chemists to explore the behavior of platinum complexes[‌157‌‌159‌] and gold salts,[‌160‌‌162‌] and the mechanisms of these skeletal reorganizations have been subjected to both experimental and theoretical scrutiny.[‌163‌‌167‌] Moreover, these transformations are utilized in some elegant natural product syntheses;[‌151‌,‌168‌] most of this chemistry has already been reviewed.[‌169‌‌172‌] The first cyclizations to be described were performed on simple enynes 164 in the presence of platinum(II) chloride as the catalyst and toluene as the solvent (Scheme 58, Method A).[‌156‌‌158‌] Other solvents such as tetrahydrofuran, dimethylformamide, cyclohexane, or dioxane prove to be less suitable giving the expected dienes 165 in low yields, together with other 1,4-dienes.[‌156‌,‌173‌] Cationic gold complexes are also good catalysts for these cycloisomerizations (Scheme 58, Method B).[‌160‌]

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M8 M M8 M8 Meeeee Meee Meeee (%) Mee
M M(MM8Me)8 M M M 8e 88 [‌888‌]
MMMMMM MMe8 M M M 8e 88 [‌888‌]
M MMe8 MMMMMM M M 8e 88 [‌888‌]
M M(MM8Me)8 M Me M 88e 88 [‌888‌]
M M(MM8Me)8 M M M 8e 88 [‌888‌]
M M(MM8Me)8 M M M 8eee 888 [‌888‌]
M M(MM8Me)8 M Me M 88eee 888 [‌888‌]

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M8 M e Meeee (%) Mee
M M(MM8Me)8 8 88 [‌888‌]
M M(MM8Me)8 8 88 [‌888‌]
M MMe 8 88 [‌888‌]
MM8Me MMe 8 88 [‌888‌]
MMMe MMe 8 88 [‌888‌,‌888‌]
MM8Me M 8 88 [‌888‌]
M MMe 8 88 [‌888‌]
M MMMMMMMM 8 88 [‌888‌]

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