title: Diastereoselective intermolecular rhodium-catalyzed [4 + 2 + 2] carbocyclization reactions: computational and experimental evidence for the intermediacy of an alternative metallacycle intermediate.
abstract: Intermolecular rhodium-catalyzed [m + n + o] reactions of 1,6-enynes and various pi-components (carbon monoxide, alkynes, 1,3-butadienes, etc.) provide an expeditious approach for the construction of polycyclic fragments that represent important synthons for target-directed synthesis. We present computational and experimental evidence for the existence of a previously undescribed reaction pathway for the rhodium-catalyzed [4 + 2 + 2] reaction involving a 1,6-enyne. This model clearly demonstrates the origin of the excellent diastereoselectivity in this type of reaction and the remarkable tolerance of both (E)- and (Z)-isomers within the 1,6-enyne, which is generally prone to competitive ene-cycloisomerization.
authors.affiliation: Department of Chemistry and School of Informatics, Indiana University, Bloomington, IN 47405, USA. mbaik@indiana.edu
authors.forename: Mu-Hyun
authors.initials: MH
authors.lastname: Baik
authors.forename: Erich W
authors.initials: EW
authors.lastname: Baum
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Burland
authors.forename: P Andrew
authors.initials: PA
authors.lastname: Evans