318276-73-2Relevant academic research and scientific papers
Copper-catalyzed tandem C-N bond formation: An efficient annulative synthesis of functionalized cinnolines
Ball, Catherine J.,Gilmore, Jeremy,Willis, Michael C.
supporting information; experimental part, p. 5718 - 5722 (2012/08/14)
Cinn-tillating synthesis: The combination of a readily available copper catalyst, a simple hydrazide nucleophile, and established difunctionalized building blocks provides a new, flexible route to an under-developed class of aromatic heterocycles, cinnolines (see scheme). Copyright
Cyclization of 1-(2-alkynylphenyl)-3,3-dialkyltriazenes: A convenient, high-yield synthesis of substituted cinnolines and isoindazoles
Kimball, David B.,Weakley, Timothy J. R.,Haley, Michael M.
, p. 6395 - 6405 (2007/10/03)
A new route to isoindazoles and cinnolines through the cyclization of (2-alkynylphenyl)triazenes under neutral conditions is presented. The products that result from heating the starting triazenes depend on both the type of alkyne ortho to the triazene functionality and the temperature used. Butadiyne moieties ortho to dialkyltriazenes yield bis-isoindazole dimers when heated to 150 °C in MeI. A requirement for cyclization in MeI is that the (2-alkynylphenyl)triazene must contain a suitably electron-withdrawing substituent on the phenyl ring to deactivate the triazene toward methylation-induced decomposition to an iodoarene. Ethynyl moieties ortho to dialkyltriazenes yield both isoindazole dimers as well as 3-formylisoindazoles when subjected to the same conditions. Replacing MeI with 1,2-dichlorobenzene as solvent allows for the general cyclization of (2-ethynylphenyl)dialkyltriazenes. Heating to 170 °C results in a mixture of isoindazole and cinnoline products, whereas the cinnolines are produced exclusively in high yield at 200 °C. Alternatively, the isoindazoles can be obtained in good to excellent yield by stirring a 1,2-dichloroethane solution of the starting triazene with CuCl overnight at 50 °C.
Deciphering the mechanistic dichotomy in the cyclization of 1-(2-ethynylphenyl)-3,3-dialkyltriazenes: Competition between pericyclic and pseudocoarctate pathways
Kimball, David B.,Weakley, Timothy J. R.,Herges, Rainer,Haley, Michael M.
, p. 13463 - 13473 (2007/10/03)
The mechanistic aspects of the cyclization of (2-ethynylphenyl)triazenes under both thermal and copper-mediated conditions are reported. For cyclization to an isoindazole, a carbene mechanistic pathway is proposed. The carbene intermediate can react with oxygen, dimerize to give an alkene, or be trapped either intermolecularly (using 2,3-dimethyl-2-butene to generate a cyclopropane) or intramolecularly (using a biphenyl moiety at the terminus of the acetylene to form a fluorene). Density-functional theory (DFT) calculations support a pseudocoarctate pathway for this type of cyclization. Thermal cyclization to give a cinnoline from (2-ethynylphenyl)triazenes is proposed to occur through a pericyclic pathway. DFT calculations predict a zwitterionic dehydrocinnolinium intermediate that is supported by deuterium trapping studies as well as cyclizations performed using a 2,2,6,6-tetramethylpiperidine moiety at the 3-position of the triazene.
Thermal Cyclization of (2-Ethynylphenyl)triazenes: Facile Synthesis of Substituted Cinnolines and Isoindazoles
Kimball, David B.,Hayes, Austin G.,Haley, Michael M.
, p. 3825 - 3827 (2007/10/03)
formula presented High-temperature intramolecular cyclization of N,N-dialkyl-N′-substituted-2-ethynylphenyl)triazenes provides under neutral conditions both 6-substituted cinnolines and 5-substituted isoindazoles in moderate to excellent yields.
