1-Metalla-1,3,5-hexatrienes and Related Compounds

C8K-Promoted Self-Condensation and Self-Condensation-Cycloisomerization Reactions of ,-Unsaturated Fischer Carbene Complexes

“…In conclusion, the reaction of α , β ‐unsaturated chromium( 0 ) or tungsten( 0 )carbene complexes and C 8 K occurs through one‐electron transfer, from the interstitial potassium to the organochromium complex, to generate intermediate radical anions. These intermediates undergo a tail‐to‐tail dimerization to form biscarbene anions, which upon protonation with a strong acid produce complexes 8 or 1,8‐dichroma‐1,3,5,7‐tetraene complexes 14 which convert in situ into cyclopentadienylchromium( 0 )carbenes 9 18. This mechanistic proposal is supported by deuteration experiments.…”

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“…These intermediates undergo a tail-to-tail dimerization to form biscarbene anions, which upon protonation with a strong acid produce complexes 8 or 1,8-dichroma-1,3,5,7tetraene complexes 14 which convert in situ into cyclopentadienylchromium(0)carbenes 9. [18] This mechanistic proposal is supported by deuteration experiments. Complexes 8 may in turn be transformed into functionalized cyclohexenes by Pdcatalyzed ring closure.…”

Diastereoselective Synthesis of Cycloheptadienol Derivatives by a Formal [5+2] Carbocyclization Reaction of α,β,γ,δ‐Diunsaturated (Methoxy)carbene Complexes with Methyl Ketone Lithium Enolates

“…These results prompted us to study the reaction of α,β,γ,δ‐diunsaturated (methoxy)carbene complexes11 with methyl ketone lithium enolates. Here we report a new diastereoselective route to seven‐membered carbocycles under very mild conditions.…”