312326-18-4Relevant articles and documents
Is an iodine atom almighty as a leaving group for Bu3SnH-mediated radical cyclization? The effect of a halogen atom on the 5-endo-trig radical cyclization of N-vinyl-α-halo amides
Tamura, Osamu,Matsukida, Hana,Toyao, Atsushi,Takeda, Yoshifumi,Ishibashi, Hiroyuki
, p. 5537 - 5545 (2007/10/03)
The effect of a halogen atom as a leaving group on Bu3SnH-mediated 5-endo-trig radical cyclization of N-(cyclohex-1-enyl) α-halo amides was examined. The cyclization of α-chloro amides occurred with a high degree of efficiency, whereas the corresponding α-iodo congeners gave only limited quantities of cyclization products. A detailed study revealed that these phenomena could be attributed to the initial conformations of α-halo amides. The cyclizing ability of α-iodo amides can be restored with Bu3SnCl or Bu3SnF as an additive. The cyclization of an α-iodo amide in the presence of Bu3SnF could be applied to a short-step synthesis of lycoranes featuring sequential 5-endo-trig and 6-endo-trig radical cyclizations.