Access to α-Cyano Carbonyls Bearing a Quaternary Carbon Center by Reductive Cyanation
Reductive cyanation of tertiary alkyl bromides using electrophilic cyanating reagent and zinc reductant was developed, providing various α-cyano ketones, esters, and carboxamides containing a nitrile-bearing all-carbon quaternary center in good to excellent yields under mild reaction conditions. The corresponding reaction mechanism involving in situ generated organozinc reagent and reactivity distinction was elucidated by density functional theory computation.
Asymmetric Hydroacylation Involving Alkene Isomerization for the Construction of C3-Chirogenic Center
A new transformation pattern for enantioselective intramolecular hydroacylation has been developed involving an alkene isomerization strategy. Proceeding through a five-membered rhodacycle intermediate, 3-enals were converted to C3- or C3,C5-chirogenic cyclopentanones with satisfactory yields, diastereoselectivities, and enantioselectivities. A catalytic cycle has been theoretically calculated and the origin of the stereoselection is rationally explained.
Selective Synthesis of β-Ketonitriles via Catalytic Carbopalladation of Dinitriles
A practical, convenient, and highly selective method of synthesizing β-ketonitriles from the Pd-catalyzed addition of organoboron reagents to dinitriles has been developed. This method provides excellent functional-group tolerance, a broad scope of substrates, and the convenience of using commercially available substrates. The method is expected to show further utility in future synthetic procedures.
Rhodium-Catalyzed Addition of Aryl Boronic Acids to 2,2-Disubstituted Malononitriles
β-Ketonitriles bearing a quaternary carbon at the 2-position were prepared through Rh-catalyzed addition of aryl boronic acids to 2,2-disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro-Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β-ketonitriles. The products could be further derivatized to valuable chiral α,α-disubstituted-β-aminonitriles through addition reactions to the corresponding N-tert-butanesulfinyl imines.
Malapit, Christian A.,Caldwell, Donald R.,Luvaga, Irungu K.,Reeves, Jonathan T.,Volchkov, Ivan,Gonnella, Nina C.,Han, Zhengxu S.,Busacca, Carl A.,Howell, Amy R.,Senanayake, Chris H.
supporting information
p. 6999 - 7002
(2017/06/06)
MESOMERIC ANIONS. X. METHYLATION OF ALKALI-METAL DERIVATIVES OF SOME 1,3-KETONITRILES
The effect of polar factors on the relative nucleophilicity of the oxygen and carbon reaction centers in the alkali-metal derivatives of 2-(X-benzoyl)acetonitriles, 2-(X-benzoyl)propionitriles, and 2-(X-phenyl)acetylacetonitriles was investigated.During methylation with methyl iodide and methyl p-toluenesulfonate in DMFA the ratio of the C- and O-methylation products for all the investigated compounds decreases with increase in the accepting power of the substituent X.It was shown that the sensitivity of the C-reaction center to the effect of the substituent X is greater than that of the O-center.
Emelina, E. E.,Ershov, B. A.
p. 692 - 696
(2007/10/02)
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