N-Bromosaccharin/$Mg(ClO_4)_2$ is an effective and regioselective system for $\alpha}$-monobromination of 1,3-dicarbonyl compounds. A wide variety of $\beta}$-keto esters and 1,3-diketones in reaction with this system afforded a regioselectively $\alpha}$-monobrominated products. The bromination reaction can be conducted at 0-5 $^\circ}C$ either in solution or under solvent-free conditions.
A relay visible-light photoredox catalysis strategy has been accomplished. Three successive photoredox cycles (one oxidative quenching cycle and two reductive quenching cycles) are engaged in a single reaction with one photocatalyst. This strategy enables formal [4 + 1] annulation of hydrazones with 2-bromo-1,3-dicarbonyl compounds, which functionalizes three C–H bonds of hydrazones. This method affords
TsNBr2 reacts readily with olefins to produce α-bromo ketones at room temperature. The synthesis was carried out by treating an olefin with TsNBr2 in acetone–water mixture in 30:1 ratio. Excellent yield of corresponding α-bromo ketone could be achieved within a short time.
Organic Dye-Catalyzed Intermolecular Radical Coupling of α-Bromocarbonyls with Olefins: Photocatalytic Synthesis of 1,4-Ketocarbonyls Using Air as an Oxidant
作者:Soumyadeep Roy Chowdhury、Deepak Singh、Injamam Ul Hoque、Soumitra Maity
DOI:10.1021/acs.joc.0c01985
日期:2020.11.6
α-bromocarbonyls where aerial oxygen played a role of an oxidant to install the keto-oxygen functionality. This unique process is compatible with both internal and terminal olefins and tolerates a diverse array of functional groups (ketone, ester, amide, diketones, ketoester, and malonate). This process is mild and environmentally friendly and deals with greener oxidants like oxygen, affording 1,4-ketocarbonyls as
transformation of alkynes by controlled manipulation of TsNBr2 mediated process. Alkynes could be readily converted to ketones and α-bromoketones via an oxybromination–debromination sequence. When alkynes are treated successively with TsNBr2, KI and Na2SO3 in a mixture of acetone and water at roomtemperature, corresponding ketones were obtained. On the other hand, treatment of alkynes with TsNBr2 and
通过控制TsNBr 2介导的过程,开发了炔烃的氧化转化的新方法。炔烃可以很容易地通过氧溴化-脱溴序列转化为酮和α-溴代酮。在室温下,在丙酮和水的混合物中依次用TsNBr 2,KI和Na 2 SO 3处理炔烃时,可获得相应的酮。另一方面,用TsNBr 2和Na 2 SO 3处理炔烃在室温下,在乙酸乙酯,丙酮和水的混合物中,可生成相应的α-溴代酮。还可以在室温下使用TsNBr 2在很短的时间内由相应的炔烃合成1-溴炔烃。在所有情况下,都可获得相应产品的优异收率。