133318-39-5Relevant articles and documents
Access to α-Cyano Carbonyls Bearing a Quaternary Carbon Center by Reductive Cyanation
Ren, Xinyi,Shen, Chaoren,Wang, Guangzhu,Shi, Zhanglin,Tian, Xinxin,Dong, Kaiwu
supporting information, p. 2527 - 2532 (2021/05/05)
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.
Unexpected differences in the α-halogenation and related reactivity of sulfones with perhaloalkanes in KOH-t-BuOH
Meyers, Cal Y.,Chan-Yu-King, Roch,Hua, Duy H.,Kolb, Vera M.,Matthews, Walter S.,Parady, Thomas E.,Horii, Toyokazu,Sandrock, Paul B.,Hou, Yuqing,Xie, Songwen
, p. 500 - 511 (2007/10/03)
Most alkyl phenyl sulfones are readily α-chlorinated with CCl4 and α-brominated with CBrCl3 in KOH-t-BuOH via radical-anion radical pair (RARP) reactions. While isopropyl mesityl sulfone (4) is easily α-chlorinated with CCl4, it was completely recovered when treated with the more reactive CBrCl3. Subsequent investigations showed the latter result to be due to the poor acidity of 4 together with the rapid depletion of CBrCl3 and KOH by their reaction with each other, and led to a variety of other important results. 4-Hydroxyphenyl isopropyl sulfone (6) is unreactive with either CCl4 or CBrCl3 in KOH-t-BuOH, its phenoxide anion strongly reducing the electronegativity of the sulfonyl group, thereby inhibiting α-anion formation. This effect is reversed by the electron-withdrawing influence of two α-phenyls, so that benzhydryl 4-hydroxyphenyl sulfone (8) is readily α-halogenated in KOH-t-BuOH with CCl4 or CBrCl3. On further contact with KOH-t-BuOH the α-halogenated sulfones from 8 are decomposed into benzophenone and phenol. While the α-halogenated derivatives of 4-methoxyphenyl benzhydryl sulfone (9) are stable to base, they are decomposed even under mildly acidic conditions into 4-methoxyphenyl 4-methoxybenzenethiolsulfonate (9c), phenol, and benzophenone. Mono-α-halogenation of benzyl phenyl sulfone (10) enhances the rate of the subsequent halogenation, so that α,α-dihalogenation is attained while much substrate is still present and the mono-α-halogenated product is not detected. The ease of reductive debromination of α-bromo sulfones with Cl3C- was correlated with the stability of the formed α-anions, explaining the success with α-bromobenzylic sulfones but failure with α-bromoalkyl sulfones. In the presence of air and the absence of competing halogenation, formation of the α-anions of alkyl aryl sulfones is quickly accompanied by oxidative cleavage by atmospheric O2, leading to the formation of arenesulfonyl alcohols, arenesulfonyl halides, and haloarenes.
