کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5218537 | 1383330 | 2012 | 18 صفحه PDF | دانلود رایگان |
Model compounds 3 and 5 have been studied to determine the orientation of the reacting double bonds in the transition state of the allylmetal-aldehyde addition. These models were designed to remove any intrinsic steric bias for the formation of the bicyclic products that would obfuscate a stereoelectronic contribution to the transition states. Model system 3 revealed a modest preference for the synclinal transition state, albeit in very low yields. Model system 5 underwent selective and largely Lewis acid independent cyclization primarily via a synclinal transition state. The high proximal selectivity observed in these cyclizations likely reflects the selectivity of an unhindered allylmetal-aldehyde addition for the synclinal transition state and results from a stereoelectronic preference, not an intrinsic steric bias, for the synclinal arrangement of double bonds.
Journal: Tetrahedron - Volume 68, Issue 37, 16 September 2012, Pages 7701-7718