On the Origin of Cis Selectivity in the Cyclization of N-Protected 2-Substituted 3-Aza-5-hexenyl Radicals: A Density Functional Study
David Shanks, Stefan Berlin, Magnus Besev, Henrik Ottosson and Lars Engman*
*Department of Organic Chemistry, Institute of Chemistry, Box 599, Uppsala University, 751 24, Uppsala, Sweden, Email: lars.engmankemi.uu.se
D. Shanks, S. Berlin, M. Besev, H. Ottosson, L. Engman, J. Org. Chem., 2004, 69, 1487-1491.
DOI: 10.1021/jo030294h (free Supporting Information)
Reductive radical cyclization of N-allyl-N-dimethylphosphinoyl-2-aminopropyl phenyl selenide using tris(trimethylsilyl)silane (TTMSS) / AIBN under UV irradiation gave the corresponding pyrrolidine in 74% yield and a cis/trans ratio of 10/1 which was superior to thermal cyclization.
The diastereomeric ratio was not as good as that obtained using the diphenylphosphonoyl protecting group (M. Besev, L. Engman, Org. Lett., 2000, 2, 1589-1593).
Pyrrolidines from β-Aminoselenides via Radical Cyclization. Diastereoselectivity Control by N-Substituent
M. Besev, L. Engman, Org. Lett., 2000, 2, 1589-1593. DOI: 10.1021/ol005829x