inexpensive NH4SCN has been developed using carbonnitride (g-C3N4) as a general heterogeneous catalyst in a greensolvent under an air atmosphere and the irradiation of a blue LED. Various thiocyanated heterocycles including indolo[2,1-a]isoquinolin-6(5H)-ones, benzimidazo[2,1-a]isoquinolin-6(5H)-ones, thioflavones, azaspiro[4.5]trienones and imidazo[1,2-a]pyridines were successfully synthesized in good
已经开发了一种无金属的光催化策略,用于在廉价的NH 4 SCN中以氮化碳(gC 3 N 4)作为绿色溶剂中的普通多相催化剂,在空气气氛下和蓝色LED的照射下制备硫氰化杂环。各种硫氰酸盐杂环,包括吲哚[2,1- a ]异喹啉-6(5 H)-one,苯并咪唑并[2,1- a ]异喹啉-6(5 H)-one,硫代黄酮,氮杂螺[4.5]三烯酮和咪唑[ 1,2-一以高产率(高达96%)成功合成了]吡啶。重要的是,这种无金属和无外部氧化剂的方法使用碳酸二甲酯作为绿色介质,避免了传统的挥发性有机溶剂。此外,可循环使用的gC 3 N 4催化剂可使用至少8次,而不会显着降低活性。
Expeditious Access to Spiro-Fused 2,5-Cyclohexadienones <i>via</i> Thio(seleno)cyanative <i>ipso</i>-Cyclization
作者:Chada Raji Reddy、Uprety Ajaykumar、Dattahari H. Kolgave
DOI:10.1021/acs.joc.0c02270
日期:2020.12.4
A facile oxidative dearomatization of N-(p-methoxyaryl)propiolamides has been established for the synthesis of spiro-fused 2,5-cyclohexadienone frameworks via thio(seleno)cyanative ipso-cyclization in the presence of cericammoniumnitrate (CAN) as the oxidant. The present method, involving the formation of C–S and C–C bonds, was also extended to (p-methoxyaryl)propiolates for thiocyanative ipso-cyclization
A Lewis acid-catalyzed cyclization of N-(p-methoxyphenyl)-3-phenylpropionamide with N-thiocyanosuccinimide has been accomplished under mild conditions. Thus, a series of thiocyanato-containing spirocyclohexadienones was obtained in moderate to excellent yields with a good functional group tolerance and a wide range of substrates. It provides an alternative approach for the synthesis of functionalized
Electrophilic <i>ipso</i>-Cyclization of <i>N</i>-(<i>p</i>-Methoxyaryl)propiolamides Involving an Electrophile-Exchange Process
作者:Bo-Xiao Tang、Qin Yin、Ri-Yuan Tang、Jin-Heng Li
DOI:10.1021/jo8018297
日期:2008.11.21
A novel electrophilic ipso-cyclization involving an electrophile-exchange process has been developed. In the presence of CuX (X = I, Br, SCN) and electrophilic fluoride reagents, a variety of N-(p-methoxyaryl)propiolamides and 4-methoxyphenyl 3-phenylpropiolate were cyclized to selectively afford the corresponding spiro[4.5]decenones in moderate to good yields. It is noteworthy that two azaquaternary tricyclic products were synthesized through a two-step pathway involving an electrophilic ipso-cyclization and then an intramolecular Heck reaction.