21772-15-6Relevant academic research and scientific papers
N-Heterocyclic Carbene-Catalyzed Umpolung of Alkynyl 1,2-Diketones
Kong, Xiangwen,Zhang, Guoxiang,Yang, Shuang,Liu, Xiaozhi,Fang, Xinqiang
, p. 2729 - 2734 (2017/08/23)
The umpolung of alkynyl 1,2-diketones via N-heterocyclic carbene (NHC) catalysis was achieved for the first time, allowing the rapid access to a large variety of synthetically and pharmaceutically important α-pyrones under very mild conditions. A completely new NHC-catalyzed umpolung pattern involving an O-acylated allenolate as the key intermediate was proposed. Moreover, an unprecedented reaction pathway, featured by a series of group migrations and new bond formation, was postulated to demonstrate the formation of the products. (Figure presented.).
Photoaddition of alkenes to conjugated α-diketones: Tandem cyclizations leading to tetrasubstituted furans
Mukherjee,Margaretha,Agosta
, p. 3388 - 3391 (2007/10/03)
Photocycloaddition of 9a-c with 2 leads cleanly to tetrasubstituted furans 12a-c, respectively, in yields of ~85%. The reactive triplet is efficiently sensitized by 2-benzoylnaphthalene and quenched by anthracene, indicating that E(T) is in the range 43-58 kcal/mol. A mechanism is proposed involving an alkyl propargyl biradical (as 10) that closes first to a vinyl carbene (as 11) and then to product. Reaction of 9c with 20 furnishes only 22, and this result rules out an alternative mechanism in which the order of steps leading to the carbene is reversed.
Novel and Convenient Routes to Functionalized Alkynyl Ketones from 1-(Benzotriazol-1-yl)propargyl Ethyl Ethers
Katritzky, Alan R.,Lang, Hengyuan
, p. 7612 - 7618 (2007/10/03)
1-(Benzotriazol-1-yl)propargyl ethyl ethers, readily accessible from propargyl aldehyde diethyl acetals and benzotriazole, undergo smooth lithiation at the methine carbon and subsequent reactions with alkyl halides, aldehydes, ketones, imines, esters, trialkylsilyl chlorides, dialkyl carbonates, and isocyanates to yield the corresponding substituted ethers.Hydrolysis of these intermediates under acidic conditions affords a wide variety of alkynyl ketones bearing hydroxy, amino, acyl, trimethylsilyl, alkoxycarbonyl, and (alkylamino)carbonyl substituents at the α-position in good to excellent overall yields.
