| Autor: |
Kuo JL; Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States., Lorenc C; Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States., Abuyuan JM; Department of Chemistry , Barnard College , 3009 Broadway , New York , New York 10027., Norton JR; Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States. |
| Abstrakt: |
Radical cyclizations are most often achieved with Bu 3 SnH in the presence of a radical initiator, but environmental considerations demand that alternative reagents be developed-ones that can serve as a synthetic equivalent to the hydrogen atom. We have revisited [CpV(CO) 3 H] - , a known replacement for Bu 3 SnH, and found that it can be used catalytically under H 2 in the presence of a base. We have carried out tin-free catalytic radical cyclizations of alkyl iodide substrates. The reactions are atom-efficient, and the conditions are mild, with broad tolerance for functional groups. We have, for example, achieved the first 5-exo radical cyclization involving attack onto a vinyl chloride. We suggest that the radicals are generated by an initial electron transfer. |
