1201-25-8Relevant articles and documents
A Versatile Synthetic Method of 1-Alkylazulenes and Azulene by the Reactions of 3-Methoxycarbonyl-2H-cycloheptafuran-2-one with in situ Generated Enamines
Yasunami, Masafumi,Miyoshi, Shiro,Kanegae, Noriko,Takase, Kahei
, p. 892 - 899 (1993)
Methyl 3-alkylazulene-1-carboxylates were synthesized in high yields by the reaction of 3-methoxycarbonyl-2H-cycloheptafuran-2-one with in situ generated morpholine enamines of aldehydes.Treatment of the esters with 100percent phosphoric acid gave 1-alkylazulenes in excellent yields.Azulene was also synthesized in a good yield via methyl azulene-1-carboxylate with a modification of this method.
Regioselective and Chemodivergent Synthesis of Azulenolactones and Azulenolactams from Rhodium(III)-Catalyzed Reactions of Azulenecarboxamides with Sulfoxonium Ylides
Lee, Seung Cheol,Son, Jeong-Yu,Kim, Jin Young,Eom, Hyeonsik,Jang, Seong Bin,Lee, Phil Ho
, p. 512 - 524 (2020/11/30)
A regioselective and chemodivergent synthetic approach for azulenolactones and azulenolactams as a new scaffold was demonstrated through Rh(III)-catalyzed reaction of N-methoxyazulene-1-carboxamides with sulfoxonium ylides. Sulfoxonium ylides that act as a precursor of secondary carbene was described, leading to the selective formation of azulenolactones and azulenolactams bearing two substituents on a newly introduced double bond. This method demonstrated functionalization of less reactive 2-position of azulene to overcome the natural reactivity. (Figure presented.).
Expansion of Azulenes as Nonbenzenoid Aromatic Compounds for C-H Activation: Rhodium- And Iridium-Catalyzed Oxidative Cyclization of Azulene Carboxylic Acids with Alkynes for the Synthesis of Azulenolactones and Benzoazulenes
Maeng, Chanyoung,Son, Jeong-Yu,Lee, Seung Cheol,Baek, Yonghyeon,Um, Kyusik,Han, Sang Hoon,Ko, Gi Hoon,Han, Gi Uk,Lee, Kyungsup,Lee, Kooyeon,Lee, Phil Ho
, p. 3824 - 3837 (2020/02/28)
Rhodium-catalyzed oxidative [4 + 2] cyclization reactions through the C-H activation of azulene carboxylic acids as nonbenzenoid aromatic compounds with symmetrical and unsymmetrical alkynes were developed under aerobic conditions, which produced azulenolactone derivatives with a wide substrate scope and excellent functional group tolerance. Interestingly, azulenic acids in reaction with alkynes underwent iridium-catalyzed [2 + 2 + 2] cyclization accompanied by decarboxylation to afford tetra(aryl)-substituted benzoazulene derivatives. The reactivity order for C-H activation reaction is greater toward azulene-6-carboxylic acid, azulene-1-carboxylic acid, and azulene-2-carboxylic acid. For the first time, the expansion of azulenes having directing group as nonbenzenoid aromatic compounds for C-H activation was successful, indicating that nonbenzenoid aromatic compounds can be used as good substrates for the C-H activation reaction. Therefore, the research area of C-H activation will certainly expand to nonbenzenoid aromatic compounds in future.
