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.
Efficient microwave induced direct α-halogenation of carbonyl compounds
作者:Jong Chan Lee、Jin Young Park、So Young Yoon、Yong Hun Bae、Seung Jun Lee
DOI:10.1016/j.tetlet.2003.10.133
日期:2004.1
A novel and direct method for the synthesis of α-halocarbonyl compounds using sequential treatment of carbonyl compounds with [hydroxy(tosyloxy)iodo]benzene followed by magnesium halides under solvent-free microwave irradiation conditions is described.
Phase-Transfer-Catalyzed Asymmetric Alkylation of α-Benzoyloxy-β-keto Esters: Stereoselective Construction of Congested 2,3-Dihydroxycarboxylic Acid Esters
Highly enantioselective phase‐transfer‐catalyzed alkylation of tert‐butyl 2‐benzoyloxy‐3‐oxobutanoate was realized by the use of an N‐spiro chiral quaternary ammonium salt, as a complementary approach to the asymmetric hydroxylation of α‐alkyl‐β‐keto esters. The synthetic utility of the alkylated compounds is highlighted by the diastereoselective reduction and alkylation of the remaining ketone moiety
A Mild and Regioselective Method for α-Bromination of β-Keto Esters and 1,3-Diketones Using Bromodimethylsulfonium Bromide (BDMS)
作者:Abu T. Khan、Md Ashif Ali、Papori Goswami、Lokman H. Choudhury
DOI:10.1021/jo061501r
日期:2006.11.1
Bromodimethylsulfonium bromide has been found to be an effective and regioselective reagent for α-monobromination of β-ketoesters and 1,3-diketones. A wide variety of β-ketoesters and 1,3-diketones undergo chemoselective α-monobromination with excellent yields at 0−5 °C or room temperature. The notable advantages of this protocol are no need of chromatographic separation, use of less hazardous reagent