139164-75-3Relevant academic research and scientific papers
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
Determination of the Absolute Configuration and Enantiomeric Purity of Allylic and Acetylenic Alcohols
Yasuhara, Fujiko,Yamaguchi, Shozo,Takeda, Masayuki,Abe, Takaaki,Miyano, Sotaro
, p. 3390 - 3394 (2007/10/02)
The relative magnitude of steric bulk of saturated vs. unsaturated substituents in the title compounds has been estimated by a lanthanoid induced shift (LIS) study of these (R)-(+)-α-methoxy-α-(trifluoromethyl)phenylacetate esters by 1H NMR spectroscopy: CH2=C(Me)- > Pentyl > n-Pr > Et = CH2=CH- > Me > Ethynyl; Ph > Cyclohexyl.These results allow the assignment of the absolute configurations of both cyclic and acyclic unsaturated alcohols.Furthermore, the relative intensity of well-separated OMe signals for those diastereomeric MTPA esters can be used for the determination of the percent ee of the original alcohols.
