in the past 10 years, organic bismuth reagents have been proved to be a better arylation reagent, which is characterized by mild reaction conditions and tolerance to the influence of other functional groups. triarylbismuth(ⅴ) derivatives are highly efficient reagents for nucleophilic aryl substitution via a coordination coupling mechanism, and these reactions occur selectively at the ipso position. typical arylation reactions include c-, n-, and o-arylation reactions.
under alkaline or neutral conditions, phenols, enols, etc. can undergo c-arylation reactions with triarylbismuth (ⅴ) derivatives or tetraphenylbismuth derivatives; using cu as a catalyst, n-arylation of amines can be carried out, while imides and lactams can be arylated smoothly under alkaline or neutral conditions without a catalyst. pentavalent organobismuth compounds are also effective reagents for the o-arylation of phenols, enols, and alcohols, and the arylation of phenols with electron-withdrawing substituents is generally dominated by o-arylation.
finet et al. studied the activity of trimethoxyphenyl bismuth derivatives in typical c-, n- and o-arylation reactions, and believed that the electronic factor was not the bismuth-mediated arylation reaction the main limiting factor, breaking the traditional understanding that organic bismuth arylation reagents can only transfer aryl groups to electron-withdrawing and electrically neutral substituents. high regioselectivity and mild reaction conditions make these reagents attractive for biopharmaceutical synthesis.
tetraphenylbismuth fluoride (ph4bif) is a new and effective reagent for regioselective α-sulfenylation of carbonyl compounds, with yields ranging from 82% to 99%. using ultra-high-valent ar3bicl2 under the action of phosphine, the regioselective aryl substitution reaction of enone and enal was completed through nucleophilic interaction to generate α-aryl enone and enal. the yields of products reacted with cyclohexenone, cyclopentenone and crotonaldehyde are 44%-93%, 62%-89% and 49%-70%, respectively. finet et al. used biⅴ compounds for the first enantioselective c-arylation of substituted enols. the arylation reaction of aminobenzanilide with triarylbismuthane occurred on the amino n instead of the amide n, and the diarylamine could be obtained in high yield by heating under reflux.
tag:   organic bismuth organic bismuth compound
