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2.8.1.3 Cobalt-Catalyzed (5 + 1) Cycloaddition

DOI: 10.1055/sos-SD-222-00208

Li, X.; Tang, W.Science of Synthesis: Metal-Catalyzed Cyclization Reactions, (20162351.

Iwasawa and co-workers have reported the preparation of 2-substituted or 2,3-disubstituted hydroquinone derivatives 13 from allenylcyclopropanols 9 using a cobalt complex (Scheme 4).[‌20‌] Upon treatment of 9 with octacarbonyldicobalt(0), carbonyl insertion complex 10 is formed. The cyclopropane ring of this complex undergoes ring expansion to generate intermediate 11, and this is followed by reductive elimination to give 12. Only activated allenylcyclopropanes are tolerated. de Meijereʼs group have compared the reactivity of octacarbonyldicobalt(0) with that of dicarbonyl(chloro)rhodium(I) dimer in the conversion of vinylcyclopropanes 14 into cyclohexenones 15 (Scheme 5).[‌21‌] The cobalt catalyst works well for most substrates, whereas the rhodium catalyst is only effective for several special vinylcyclopropanes under a carbon monoxide atmosphere.

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M8 M8 M8 M8 Meeeeeee (eee%) Meee (e) Meeee (%) Mee
(MM8)8 Me M Me8(MM)8 (8) 88 88 [‌88‌]
(MM8)8 Me M Me8Me8(MM)8 (8.8) 88 88 [‌88‌]
(MM8)8 M M Me8(MM)8 (8) 88 88 [‌88‌]
(MM8)8 M M Me8Me8(MM)8 (8.8) 88 88 [‌88‌]
(MM8)8 Me M Me8(MM)8 (8) 88 88e [‌88‌]
(MM8)8 Me M Me8Me8(MM)8 (8.8) 88 88e [‌88‌]
(MM8)8 eeeeeeeeeee M Me8(MM)8 (8) 88 88 [‌88‌]
(MM8)8 eeeeeeeeeee M Me8Me8(MM)8 (8.8) 88 88 [‌88‌]
(MM8)8 M Me Me8(MM)8 (8) 88 88 [‌88‌]
(MM8)8 M Me Me8Me8(MM)8 (8.8) 88 88 [‌88‌]
M M M M(MM8)8MMe Me8(MM)8 (8) 88 88 [‌88‌]
M M M M(MM8)8MMe Me8Me8(MM)8 (8.8) 88 <8 [‌88‌]
M M M MM=MM8 Me8(MM)8 (8) 88 88 [‌88‌]
M M M MM=MM8 Me8Me8(MM)8 (8.8) 88 <8 [‌88‌]
M M M M Me8(MM)8 (8) 88 88 [‌88‌]
M M M M Me8Me8(MM)8 (8.8) 88 <8 [‌88‌]

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References


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