开发了一种新的催化体系,并应用于LLM-105合成的氧化反应,其中质子化过硫钨酸盐结合壳聚糖用作催化剂。使用H 2 O 2作为氧化剂,可以合成吡嗪-1-氧化物,2,6-二甲氧基吡嗪-1-氧化物,2,6-二氯吡嗪-1-氧化物和2-氯吡咯。不添加三氟乙酸的6-甲氧基吡嗪-1-氧化物,为LLM-105的新颖且对环境无害的合成路线提供了重要的探索。还使用高斯03进行了理论研究,以评估氧化过程。所有的计算数据与我们的实验结果非常吻合。
Regioselective addition of Grignard reagents to <i>N</i>-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ<sup>5</sup>-2-oxopiperazines
作者:Valentine R St. Hilaire、William E Hopkins、Yenteeo S Miller、Srinivasa R Dandepally、Alfred L Williams
DOI:10.3762/bjoc.15.8
日期:——
The regioselective addition of Grignardreagents to mono- and disubstituted N-acylpyrazinium salts affording substituted 1,2-dihydropyrazines in modest to excellent yields (45-100%) is described. Under acidic conditions, these 1,2-dihydropyrazines can be converted to substituted Δ5-2-oxopiperazines providing a simple and efficient approach towards their preparation.
Xanthate-mediated intermolecular alkylation of pyrazines
作者:Qi Huang、Ling Qin、Samir Z. Zard
DOI:10.1016/j.tet.2018.08.040
日期:2018.10
An expedient approach for the intermolecular C-H functionalization of pyrazines and other heteroarenes by the radical chemistry of xanthates is reported. Incorporation of a multitude of functional alkyl groups onto these heteroarenes proceeds in good yield and good to excellent regioselectivity, leading to highly functionalized heteroaromatics.
Synthesis of pyrazine C-ribosides via direct metalation
作者:Weimin Liu、John A. Walker、Jiong J. Chen、Dean S. Wise、Leroy B. Townsend
DOI:10.1016/0040-4039(96)01121-5
日期:1996.7
A directmetalation method has been developed for the synthesis of novel pyrazine C-nucleosides. The regiochemistry was controlled by selecting different substituents on the pyrazine ring and excellent stereoselectivity was achieved via a hydride delivery strategy. The scope and limitations of this method were studied. The uniquely designed 4b is a versatile synthon for the preparation of other pyrazine
Conditions for the metalation of 2,6-dichloro- and 2,6-dimethoxy-pyrazine are defined and the lithio-derivatives are shown to react with some electrophiles. A convenient synthesis of a diazaxanthone from the lithio-derivative of the dichloro-compound is described. Couplings between phenylacetylene and iodo-derivatives of pyrazine have been carried out.