1006866-63-2Relevant academic research and scientific papers
Enantioselective Allylation Using Allene, a Petroleum Cracking Byproduct
Liu, Richard Y.,Zhou, Yujing,Yang, Yang,Buchwald, Stephen L.
, p. 2251 - 2256 (2019)
Allene (C3H4) gas is produced and separated on million-metric-ton scale per year during petroleum refining but is rarely employed in organic synthesis. Meanwhile, the addition of an allyl group (C3H5) to ketones is among the most common and prototypical reactions in synthetic chemistry. Herein, we report that the combination of allene gas with inexpensive and environmentally benign hydrosilanes, such as PMHS, can serve as a replacement for stoichiometric quantities of allylmetal reagents, which are required in most enantioselective ketone allylation reactions. This process is catalyzed by copper salts and commercially available ligands, operates without specialized equipment or pressurization, and tolerates a broad range of functional groups. Furthermore, the exceptional chemoselectivity of this catalyst system enables industrially relevant C3 hydrocarbon mixtures of allene with methylacetylene and propylene to be applied directly.
Practical and Broadly Applicable Catalytic Enantioselective Additions of Allyl-B(pin) Compounds to Ketones and α-Ketoesters
Robbins, Daniel W.,Lee, KyungA,Silverio, Daniel L.,Volkov, Alexey,Torker, Sebastian,Hoveyda, Amir H.
supporting information, p. 9610 - 9614 (2016/08/10)
A set of broadly applicable methods for efficient catalytic additions of easy-to-handle allyl-B(pin) (pin=pinacolato) compounds to ketones and acyclic α-ketoesters was developed. Accordingly, a large array of tertiary alcohols can be obtained in 60 to >98 % yield and up to 99:1 enantiomeric ratio. At the heart of this development is rational alteration of the structures of the small-molecule aminophenol-based catalysts. Notably, with ketones, increasing the size of a catalyst moiety (tBu to SiPh3) results in much higher enantioselectivity. With α-ketoesters, on the other hand, not only does the opposite hold true, since Me substitution leads to substantially higher enantioselectivity, but the sense of the selectivity is reversed as well.
SIMPLE ORGANIC MOLECULES AS CATALYSTS FOR PRACTICAL AND EFFICIENT ENANTIOSELECTIVE SYNTHESIS OF AMINES AND ALCOHOLS
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Paragraph 00205; 00206, (2013/09/12)
The present invention provides organic molecules and methods thereof for reactions between organoboron reagents and double bonds, such as imines or carbonyls, to stereoselectively provide chiral products including amines and alcohols, entities useful for
Indium-mediated asymmetric Barbier-type allylations: Additions to aldehydes and ketones and mechanistic investigation of the organoindium reagents
Haddad, Terra D.,Hirayama, Lacie C.,Singaram, Bakthan
supporting information; experimental part, p. 642 - 649 (2010/04/29)
(Chemical Equation Presented) We report a simple, efficient, and general method for the indium-mediated enantioselective allylation of aromatic and aliphatic aldehydes and ketones under Barbier-type conditions in a one-pot synthesis affording the corresponding chiral alcohol products in very good yield (up to 99%) and enantiomeric excess (up to 93%). Our method is able to tolerate various functional groups, such as esters, nitriles, and phenols. Additionally, more substituted allyl bromides, such as crotyl and cinnamyl bromide, can be used providing moderate enantioselectivity (72% and 56%, respectively) and excellent diastereoselectivity when employing cinnamyl bromide (95/5 anti/syn). However, the distereoselectivity when using crotyl bromide was poor and other functionalized allyl bromides under our method afforded low enantioselectivities for the alcohol products. In these types of indium-mediated additions, solvent plays a major role in determining the nature of the organoindium intermediate and we observed the susceptibility of some allylindium intermediates to hydrolysis in protic solvents. Under our reaction conditions using a polar aprotic solvent, we suggest that an allylindium(III) species is the active allylating intermediate. In addition, we have observed the presence of a shiny, indium(0) nugget throughout the reaction, irrespective of the stoichiometry, indicating disproportionation of indium halide byproduct formed during the reaction.
