89036-33-9Relevant academic research and scientific papers
Lithium and cesium ion-pair acidities of dibenzyl ketone. Aggregation of lithium and cesium ion pairs of the enolate ion and dianion
Gareyev, Roustam,Ciula, James C.,Streitwieser, Andrew
, p. 4589 - 4593 (1996)
Spectral study of the cesium and lithium enolates of dibenzyl ketone (DBK) showed that both salts exist as contact ion pairs in THF solutions. The spectral data for the dicesium salt of DBK indicate that it exists as triple ions in which both cations are in contact with the dianion. The dilithium salt of DBK forms triple ions of two types in THF: in one, both cations are in contact with the DBK dianion, in the other, one of the lithium cations is solvent-separated. Evidence for dimerization of the ion pairs was obtained for both lithium and cesium enolates of DBK from UV-vis spectral (blue shift of the absorbance band at higher concentrations) and acidity (the decrease of pK at higher concentrations) studies. The dimerization constant for the cesium enolate of DBK obtained from the acidity data (3.5 × 103 M-1) is considered to be more accurate than that from the spectral analysis (1.7 × 103 M-1). The lithium enolate is much less dimerized than its cesium counterpart with a dimerization constant from acidity data of 4.2 × 102 M-1. The first and second cesium pK values of DBK are 18.07 and 33.70, respectively, compared to the first lithium pK of 11.62.
Stereoselective Synthesis of Trisubstituted Vinylboronates from Ketone Enolates Triggered by 1,3-Metalate Rearrangement of Lithium Enolates
Hu, Yue,Sun, Wei,Zhang, Tao,Xu, Nuo,Xu, Jianeng,Lan, Yu,Liu, Chao
supporting information, p. 15813 - 15818 (2019/10/28)
An unprecedented stereoselective synthesis of trisubstituted vinylboronates is reported to proceed by direct borylation of lithium ketone enolates under transition-metal-free conditions. The stereospecific C?O borylation of lithium enolates was triggered by a carbonyl-induced 1,3-metalate rearrangement via a C-bound boron enolate. DFT calculations and control experiments revealed that the stereoselectivity is controlled by sterics. A variety of stereospecific trisubstituted vinylboronates, together with several tetrasubstituted vinylboronates, were conveniently synthesized with the newly developed methodology. Based on the transformation of stereospecific vinylboronate, a single isomer of Dienestrol was efficiently obtained.
