TY  - UNPB
ID  - pittir8877
UR  - http://d-scholarship-dev.library.pitt.edu/8877/
A1  - Gibney, Heather Marie
TI  - A Stereochemical Comparison Between Radical Atom Transfer Cyclizations and Organozinc Cyclizations of Primary and Secondary Hexenyl Iodides
Y1  - 2006/09/28/
N2  - Cyclized hexenylzinc iodides have been reported to give different cis:trans product ratios than the analogous radical cyclized hexenyl iodides and this has been taken as evidence that the organozinc and not radical cyclizations are involved. Unfortunately, temperature dependence was not taken into account when comparing the two sets of ratios. To further investigate these differing cis:trans ratios, three hexenyl iodides were synthesized and cyclized under radical atom transfer conditions between 5 °C and 80 °C. The resulting cis:trans product ratios were measured by gas chromatography. The cis:trans ratios observed ranged from high (i.e. cis:trans 1:13.3) to low (cis:trans 2.0:1); the selectivities decreased as the temperature increased. Comparison of cis:trans ratios of the products from the zinc cyclization to the cis:trans ratios of the products from the radical cyclizations at the same temperatures showed that the two sets of ratios were within experimental error of each other. It was concluded that the zinc mediated cyclizations of primary and secondary alkenyl iodides to give cyclopentylmethylzinc halides involve radical cyclizations.
AV  - public
KW  - atom transfer; hexenyl iodide; organozinc; radical
ER  -