BF₃⋅OEt₂‐Catalyzed Intermolecular Reactions of Vinylidenecyclopropanes with Bis(p‐alkoxyphenyl)methanols: A Novel Cationic 1,4‐Aryl‐Migration Process

Abstract

BF(3)OEt(2)-catalyzed reactions of vinylidenecyclopropanes (VDCPs) 1 with bis(aryl)methanols 2 were thoroughly investigated. When VDCPs 1 reacted with electron-rich bis(aryl)methanols 2, diastereomeric rotamers of indene derivatives formed in excellent yields by a novel cationic 1,4-aryl migration between two carbon atoms and the subsequent intramolecular Friedel-Crafts reaction pathways in the presence of BF(3).OEt(2) under mild conditions. As for electron-deficient or less-electron-rich bis(aryl)methanols 2, either trialkene products formed in good yields by direct deprotonation, or another type of indene derivative was produced by direct intramolecular Friedel-Crafts reaction, depending on the substituents on the cyclopropane of VDCPs. In addition, DFT calculations were carried out to explain the experimental results. Plausible mechanisms for all these transformations are proposed on the basis of the experimental and computational results.

Gold‐Catalyzed Cycloisomerization of Yne‐Vinylidenecyclopropanes: A Three‐Carbon Synthon for [3+2] Cycloadditions

“…Plausible mechanisms for the cycloisomerization/rearrangement of yne‐VPCPs 2 and 4 are presented in Scheme on the basis of isotope labeling experiments and on previous reports 9k. 14 In path a, the coordination of terminal alkyne in VDCP 2 ( n =1) with Au I catalyst initially generates gold species A , which cyclizes with the C‐2 carbon in the tethered VDCP to give a pair of equilibrated intermediates B and C in a 6‐ exo ‐dig manner.…”

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

“…Related reactions of allylic alcohols are not unknown: periodic acid has been shown to oxidise one of the alcohol groups in a 1,4-diol fragment to yield the corresponding aldehyde, without any further change to the remnant allylic alcohol [ 10 ]; a related mechanism has been reported for a self-coupling intermolecular reaction, which involves an intermediate allylic cation generated under acidic conditions from an electron-rich thienylmethanol derivative, where no intramolecular rearrangement took place [ 11 ]. Also worth noting, is a recent study on cationic 1,4-aryl migration observed during reactions of vinylidenecyclopropanes with electron-rich bis( p -alkoxyphenyl)methanols [ 12 ].…”

Reactions of Vinylidenecyclopropanes with Diphenyl Diselenide in the Presence of AIBN and Thermally‐Induced Further Transformations

“…In recent years, we and others have disclosed many useful transformations of VDCPs in the presence of Lewis or Brønsted acids as well as transition‐metal catalysts, subsequently enriching the chemistry of VDCPs 2–4. However, the chemistry of VDCPs having newly introduced functional groups such as alkene4h and hydroxyl group4g has been less developed thus far. Herein, we wish to report a new chemical transformation of VDCPs 2 (having an additional alkenyl group) with diphenyl diselenide in the presence of AIBN and further transformations of these products.…”