Substituent effects on the iodine-catalyzed thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates: mechanistic studies.
The thermal cyclization of 3,4-diphenylbuta-1,3-dienyl isocyanates 1, generated in situ from the corresponding azides, was investigated using iodine as a catalyst. Diphenylpyridinones 2, phenylnaphthalenes 3, and indenes 4 were produced via intramolecular ring closure. The nature of the substituents on the phenyl rings was found to be crucial to the distribution of cyclized products 2-4. The mechanism of the reaction is also discussed.
School of Pharmacy, China Medical University, No. 91, Hsueh-Shih Road, Taichung 40402, Taiwan, Republic of China. thchuang@mail.cmu.edu.tw
Ta-Hsien
TH
Chuang
Wei-Yu
WY
Chang
Chien-Fu
CF
Li
Yu-Chia
YC
Wen
Chia-Chen
CC
Tsai
D002384:Catalysis; D003500:Cyclization; D007455:Iodine / Q000737:chemistry*; D017953:Isocyanates / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013696:Temperature
C570825:3,4-diphenylbuta-1,3-dienyl isocyanate; D017953:Isocyanates; D007455:Iodine