201348-87-0Relevant academic research and scientific papers
Effect of temperature on 5-endo- and 4-exo-trig radical cyclizations of N-vinylic α-halo amides
Ishibashi, Hiroyuki,Higuchi, Masahiro,Ohba, Masashi,Ikeda, Masazumi
, p. 75 - 78 (1998)
The radical 3a generated from N-vinylic trichloroacetamide 1a provided the 5-endo-trig cyclization product 2a in boiling toluene, whereas, at room temperature, gave the 4-exo-trig cyclization product 9. The results may be explained in terms of the reversi
Regiochemistry in radical cyclizations (5-endo versus 4-exo) of N-(2-phenylthio- and 2-phenylcyclohex-1-enyl)-α-halo amides
Ishibashi, Hiroyuki,Kodama, Kazuya,Higuchi, Masahiro,Muraoka, Osamu,Tanabe, Genzoh,Takeda, Yoshifumi
, p. 7629 - 7637 (2007/10/03)
Bu3SnH-mediated radical cyclization of N-(2-phenylthiocyclohex-1-enyl)-α-halo amides was examined. Bromoacetamide 9a having no substituent α to the halogen atom cyclized exclusively in a 4-exo-trig manner, whereas the fully substituted haloamides 9c and 9e gave 5-endo-trig cyclization products. The mono-substituted haloamides 9b and 9d showed an intermediate behavior to give a mixture of 4-exo and 5-endo cyclization products. The results of experiments on the effect of reaction temperature indicated that at a low temperature, i.e. under kinetically controlled conditions, 4-exo-trig cyclization predominated. On the other hand, the 2-phenylcyclohex-1-enyl congeners 22b and 22c gave exclusively 5-endo cyclization products.
