Premium
Molecular Transformation of 2‐Methylazulenes: An Efficient and Practical Synthesis of 2‐Formyl‐ and 2‐Ethynylazulenes
Author(s) -
Shoji Taku,
Araki Takanori,
Iida Nanami,
Kobayashi Yoshiaki,
Ohta Akira,
Sekiguchi Ryuta,
Ito Shunji,
Mori Shigeki,
Okujima Tetsuo,
Yasunami Masafumi
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201701746
Subject(s) - chemistry , formylation , sodium methoxide , dimethylformamide , medicinal chemistry , derivative (finance) , reactivity (psychology) , coupling reaction , ethylene , crystal structure , orthorhombic crystal system , methanol , catalysis , stereochemistry , organic chemistry , solvent , medicine , alternative medicine , pathology , financial economics , economics
2‐Formylazulene derivatives have been obtained in good yields by the reactions of 2‐methylazulenes with N , N ‐dimethylformamide dimethyl acetal, followed by oxidative cleavage of the intermediately formed enamines with NaIO 4 . Vilsmeier formylation of 1‐phenyl‐3‐methylazulenes also afforded the corresponding 2‐formylazulenes in moderate yields. The treatment of a 2‐methylazulene derivative bearing a formyl group at the 1‐position with sodium methoxide led, through a self‐condensation reaction, to a trans ‐1‐(azulen‐1‐yl)‐2‐(azulen‐2‐yl)ethylene derivative, the structure of which was verified by single‐crystal X‐ray diffraction analysis. The 2‐formylazulenes obtained were transformed into 2‐ethynylazulenes in good yields by a modified Seyferth–Gilbert reaction. The reactivity of a 1‐iodoazulene bearing a 2‐formyl function in palladium‐catalyzed cross‐coupling reactions has also been examined.