Intramolecular trapping of cyclobutadiene

(Cyclobutadiene)iron TricarbonylA Case of Theory before Experiment

“…106 Intramolecular trapping of cyclobutadiene (eq 10) also has been reported. 107 In addition to acetylenes and olefins, diazenes have been used as trapping agents (eq 11). 108 Substituted (cyclobutadiene)iron tricarbonyl complexes of the type (C 4 H 3 CH 2 X)Fe(CO) 3 (X ) OH, Cl) were of special interest.…”

Wolff/Cope Approach to the AB Ring of the Sesterterpenoid Variecolin

“…During the course of our efforts, we elected to employ an efficacious intramolecular cyclobutadiene–olefin cycloaddition for the rapid construction of this moiety. 17,18,19 Model studies pursued toward this goal provided insight into the identification and physical properties of reaction intermediates using a readily accessible cyclopentenol analogue.…”

“…The development of a tandem Wolff/Cope rearrangement toward the fused bicyclic 8-membered AB ring fragment ( 14 ) required an expedient regio- and stereoselective synthesis of a highly substituted cyclobutane substrate (e.g., 15 ). During the course of our efforts, we elected to employ an efficacious intramolecular cyclobutadiene–olefin cycloaddition for the rapid construction of this moiety. − Model studies pursued toward this goal provided insight into the identification and physical properties of reaction intermediates using a readily accessible cyclopentenol analogue.…”

Intramolecular [2+2+1] Cycloadditions with (Cyclobutadiene)tricarbonyliron

“…In 1974, Grubbs et al studied intramolecular cycloadditions between cyclobutadiene and tethered alkynes [e.g., Eq. (4)] 2. The major product isolated from this reaction was compound 6 , which presumably was generated through rearrangement of the Dewar benzene cycloadduct 5 .…”