DOUBLE CYCLOADDITION REACTION OF PYRIDINIUM<i>N</i>-METHYLIDES TO METHYLENECYCLOPROPENES LEADING TO CAGE COMPOUNDS
作者:Otohiko Tsuge、Shuji Kanemasa、Shigeori Takenaka
DOI:10.1246/cl.1983.519
日期:1983.4.5
A new functionalization of pyridine has been demonstrated by the double cycloaddition reactions between pyridinium N-methylides and methylenecyclopropenes with unsaturated substituents at the 4-position forming a new type of cage compounds.
Synthesis of tetrasubstituted pyridazines via cascade reactions of diazocarbonyl compounds with pyridinium ylides
作者:Yu. V. Tomilov、D. N. Platonov、D. V. Dorokhov、A. A. Zhalnina
DOI:10.1007/s11172-008-0160-2
日期:2008.6
Reactions of pyridinium ylides with diazocarbonyl compounds involve the formation of functionalized azine intermediates that can undergo intramolecular cyclocondensation into tetrasubstituted pyridazines provided the starting reagents contain carbonyl groups. Reactions of pyridinium ylides with diazo compounds were studied for various substituents in both the substrates.
Azomethine ylides such as 1 and 4 in which the nitrogen atom is incorporated in a six-membered heterocyclic ring undergo regiospecific [3+2] cycloadditions with the phosphaalkynes 2a and b at 130–140 °C to furnish the phosphaindolizines 3 and 5a–c after elimination of ethyl formate or hydrogen cyanide, respectively. In contrast, dipoles of the type 6 react unspecifically with the phosphaalkyne 2a to
Reversible C ? N migration of the ethoxycarbonyl group in the reactions of pyridinium and isoquinolinium ylides derived from malonic ester with isocyanates
作者:Yuri G. Gololobov、Olga V. Dovgan、Igor R. Golding、Pavel V. Petrovskii、Irina A. Garbuzova
DOI:10.1002/hc.1104
日期:——
Pyridinium and isoquinoliniumylides (7 and 12) derived from malonic ester react in an unusual manner with isocyanates giving the new pyridiniumylide (9) and the new isoquinoliniumylide (14). C N Migration of the COOEt group takes place at room temperature, but, at an elevated temperature, reverse N C migration of the COOEt group proceeds and ylides 9 and 14 are reconverted into the starting ylides
On the mechanism of C ⇄ N migration of alkoxycarbonyl groups in reactions of pyridinium ylides with isocyanates
作者:Yu. G. Gololobov、N. V. Kashina、O. A. Linchenko、P. V. Petrovskii、N. P. Gambaryan、W. Friedrichsen
DOI:10.1023/b:rucb.0000011888.26449.21
日期:2003.10
New examples of reversible C ⇄ N migrations of alkoxycarbonyl groups, which occur in the reactions of pyridinium and 3-(diethylcarbamoyl)pyridinium ylides, viz., derivatives of dimethyl and diethyl malonates, with aryl isocyanates were studied. The mechanism of migration of the methoxycarbonyl group from the carbon atom to the nitrogen atom was considered on the basis of quantum-chemical calculations
研究了发生在吡啶鎓和 3-(二乙基氨基甲酰基)吡啶鎓叶立德反应中的烷氧羰基可逆 C ⇄ N 迁移的新例子,即丙二酸二甲酯和二乙酯的衍生物与异氰酸芳基酯的反应。在量子化学计算的基础上考虑了甲氧基羰基从碳原子迁移到氮原子的机制。吡啶鎓叶立德对异氰酸酯基团的初级攻击的产物被确定为以低势垒重排形成氨基甲酸酯,而不会形成环状中间体化合物。