Synthesis and Analysis of Substituted Bullvalenes

Abstract

Herein we detail a practical synthesis of bullvalene and a variety of mono- and disubstituted analogues through cobalt-catalysed [6+2] cycloaddition of cyclooctatetraene to alkynes, followed by photochemical di-π-methane rearrangement. The application of isomer-network analysis, coupled with quantum-chemical calculations, provides a powerful automated tool for predicting the properties of bullvalene isomer networks.

Nonconjugated Hydrocarbons as Rigid‐Linear Motifs: Isosteres for Material Sciences and Bioorganic and Medicinal Chemistry

“…They incorporated a single 13 C‐label into the bullvalene backbone and were able to differentiate dissimilar polyols by small changes in the chemical shift and intensities (Figure ) . With the recently developed method by the Fallon group, disubstituted bullvalenes are easily available now and their computational network analysis is a useful tool to understand the energetic landscape of the various isomers …”

“…[440] With the recently developed methodb yt he Fallon group, disubstituted bullvalenes are easily available now and their computational network analysis is au seful tool to understand the energetic landscape of the various isomers. [441] Af ew more examples focus on reversible carbon-carbon bond formations without the presence of heteroatoms are catalyzed olefin [442] or alkyne metathesis [443] or cycloadditions, [444] as shown below (Scheme 31). [445] These systemsa re interesting since they combine the rigidness of their arrangement with the flexible control of their formation.…”

Shapeshifting molecules: the story so far and the shape of things to come

“…Below, we discuss the recent synthetic advances that have led to more streamlined, mild syntheses of BV derivatives, as well as quantum computational analyses that predict the energetics of the resulting isomer networks. 8,9 Recent advances in bullvalene synthesis and analysis Metal-catalysed cyclisation approaches have recently expanded the scope of easily accessible BV derivatives. Echavarren 8 and Fallon 9 have employed Au(I)-catalysed and Co(I)-catalysed reactions, respectively, as crucial steps to form BV precursors.…”

“…Fallon's protocol converts (Scheme 3) cyclooctatetraene into BV, or a range of mono-and disubstituted analogues, through an elegant two-step procedure in overall yields of 28-70%. 9 In the rst step, bicyclo[4.2.2]deca-2,4,7,9-tetraene intermediates 1 are prepared by formal [6 + 2] cycloaddition of cyclooctatetraene with alkynes in the presence of a CoI 2 (dppe)/ZnI 2 /Zn catalyst system. 19 In the second step, 1 undergoes a di-p-methane photoisomerisation 18 under UV irradiation to give the BV derivative 2.…”

“…These shapeshiing molecules, therefore, exist as uxional mixtures that can be considered as self-contained dynamic structural libraries. Recent advances in synthetic methods [7][8][9] combined with resourceful computational calculations 9 have made it possible to investigate the application of these of highly dynamic systems as sensing molecules for structurally complex analytes. 7 Investigations involving tractable bistable systems have also shed light on how the shapeshiing equilibria adapt in response to external changes.…”