Single-Step Formation of Pyrimido[4,5-d]pyridazines by a Pyrimidine-Tetrazine Tandem Reaction

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• 作者：Juraj Galeta ; Michal Šála ; Martin Dračínský ; Milan Vrábel ; Zdeněk Havlas ; Radim Nencka
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：August 5, 2016
• 年：2016
• 卷：18
• 期：15
• 页码：3594-3597
• 全文大小：322K
• 年卷期：0
• ISSN：1523-7052

文摘

A straightforward synthesis of pyrimido[4,5-d]pyridazines from pyrimidines and tetrazines under basic conditions is reported. Deprotonated, substituted 5-halopyrimidines readily react with variously substituted tetrazines in a highly regioselective manner via a complex reaction pathway, which was supported by DFT calculations. This mechanism leads to the empirically observed regioisomers without going through the conceivable hetaryne intermediate. These results on 5-halopyrimidines led to development of the methodology for preparation of opposite regioisomers based on 6-halopyrimidines.