139164-76-4Relevant academic research and scientific papers
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 (1991)
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.
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.
