Hydrazone radical promoted vicinal difunctionalization of alkenes and trifunctionalization of allyls: synthesis of pyrazolines and tetrahydropyridazines.
The intramolecular addition of hydrazone radicals to carbon-carbon double bonds was achieved by using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) or DIAD (diisopropyl azodicarboxylate) as the hydrazone radical initiator as well as the carbon radical scavenger. Consequently, alkenes were difunctionalized to afford pyrazolines and tetrahydropyridazines via C-N forming 5-exo-trig and 6-exo-trig cyclizations, respectively, and allyls were trifunctionalized to afford pyrazolines via C-N forming tandem 1,5-H-shift/5-exo-trig cyclizations under metal-free neutral conditions.
State Key Laboratory of Applied Organic Chemistry, Lanzhou University , Lanzhou, Gansu 730000, People's Republic of China.
Xiao-Yong
XY
Duan
Xiu-Long
XL
Yang
Ran
R
Fang
Xie-Xue
XX
Peng
Wei
W
Yu
Bing
B
Han