334868-10-9Relevant academic research and scientific papers
Hypervalent Iodine(III) Compounds as Biaxial Halogen Bond Donors
Heinen, Flemming,Engelage, Elric,Cramer, Christopher J.,Huber, Stefan M.
, p. 8633 - 8640 (2020)
Hypervalent iodine(III) derivatives have been established as powerful reagents in organic transformations, but so far only a handful of studies have addressed their potential use as halogen-bonding noncovalent Lewis acids. In contrast to classical halogen-bond donors based on iodine(I) compounds, iodine(III) salts feature two directional electrophilic axes perpendicular to each other. Herein we present the first systematic investigation on biaxial binding to such Lewis acids in solution. To this end, hindered and unhindered iodolium species were titrated with various substrates, including diesters and diamides, via 1H NMR spectroscopy and isothermal titration calorimetry. Clear evidence for biaxial binding was obtained in two model systems, and the association strengths increased by 2 orders of magnitude. These findings were corroborated by density functional theory calculations (which reproduced the trend well but underestimated the absolute binding constants) and a cocrystal featuring biaxial coordination of a diamide to the unhindered iodolium compound.
Highly enantioselective synthesis of silahelicenes using Ir-catalyzed [2+2+2] cycloaddition
Shibata, Takanori,Uchiyama, Toshifumi,Yoshinami, Yusuke,Takayasu, Satoshi,Tsuchikama, Kyoji,Endo, Kohei
supporting information; scheme or table, p. 1311 - 1313 (2012/02/16)
Silahelicenes, which contain two silole moieties in a helically chiral structure, were synthesized by a chiral Ir-catalyzed intermolecular [2+2+2] cycloaddition of tetraynes with diynes along with a Ni-mediated intramolecular [2+2+2] cycloaddition. The photophysical properties of the obtained highly enantiomerically enriched silahelicenes (up to 93% ee) were also measured. The Royal Society of Chemistry 2012.
Carbonyl- and carboxyl-substituted enediynes: Synthesis, computations, and thermal reactivity
Koenig,Pitsch,Klein,Vasold,Prall,Schreiner
, p. 1742 - 1746 (2007/10/03)
The influence of electron-withdrawing groups (carbonyl and carboxyl) at the alkyne termini on the reactivity of enediynes was investigated by a combination of experimental and computational techniques. While the general chemical reactivity of such enediynes, especially if non-benzannelated, is increased markedly, the thermal cyclization, giving rise to Bergman cyclization products, is changed little relative to the parent enediyne system. This is evident from kinetic measurements and from density functional theory (DFT, BLYP/6-31G* + thermal corrections) computations of the experimental systems which show that the Bergman cyclization barriers slightly (3-4 kcal/mol) increase, in contrast to earlier theoretical predictions. The effect on the endothermicities is large (ΔΔHr = 7-12 kcal/mol). Hence, the increased reactivity of the substituted enediynes is entirely due to nucleophiles or radicals present in solution. This was demonstrated by quantitative experiments with diethylamine and tetramethyl piperidyl oxide (TEMPO) which both give fulvenes through 5-exo-dig cyclizations.
