Complex-Induced Proximity Effects: The Effect of Varying Directing-Group Orientation on Carbamate-Directed Lithiation Reactions
作者:Kathleen M. Bertini Gross、Peter Beak
DOI:10.1021/ja002662u
日期:2001.1.1
restricted carbamates 7, 10, 11, and 15 undergo lithiation via complexes more efficiently than Boc amines 4-6. These results along with semiempirical calculations suggest that a small dihedral angle and a calculated distance of 2.78 A between the carbamate carbonyl oxygen and the proton to be removed are favorable for a carbamate-directed lithiation. A series of tin-lithium exchange experiments on