[2.pi. + 6.pi.] Cycloaddition reactions between ligands coordinated to an iron atom

Synthesis and reactions of some cyclopentadienyl complexes of platinum

“…Of particular interest are reactions rearrangement occurs: the unreacted ql-Cp diswhere the metal is thought to lift symmetry places the COD and changes from 171 to q5, and constraints of otherwise 'symmetry forbidden' the norbornadiene is bonded as shown. thermal cycloadditions (19). The exact manner in which this is achieved is not known but metals 0 might cause normally forbidden concerted reactions to proceed in a stepwise manner (20).…”

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…In refluxing hexane the carbon termini of the organic ligand in 381 are C-C connected and, under the reaction conditions, the resulting cyclohexa-1,4-diene in 382 immediately undergoes a 1,3-hydrogen shift to give the isolated cyclohexa-1,3-diene complex 383. 606 The authors suggest that the also photochemically induced [6+2] cycloaddition of (η 4 -cycloheptatriene)Fe(CO) 3 with dimethyl acetylenedicarboxylate 608 (cf. section II.E), and the formation of 1,2-dimethylcyclohexa-1,4-diene from 2-butyne and butadiene, catalyzed by Fe(C 8 H 8 ) 2 609 may proceed by a similar stepwise reaction path.…”

Cobalt(I)‐Catalyzed Cycloaddition of Functionally Substituted Alkynes and 1,3‐Diynes to 1,3,5,7‐Cyclooctatetraene in the Synthesis of Bicyclo[4.2.2]deca‐2,4,7,9‐tetraenes

“…According to published data, BDTs can be synthesized via catalytic or photochemical [6π+2π]‐cycloaddition of simple alkynes to 1,3,5,7‐cyclooctatetraene (COT), or complexes of COT with Fe or Cr carbonyls, or under the action of stoichiometric amounts of Ru or Mo compounds. Despite the fact that the first publications addressing the [6π+2π]‐cycloaddition of CneOT to alkynes appeared more than 30 years ago, this reaction has still been explored only for a small number of simple alkyl‐ or phenyl‐substituted acetylenes.…”