Enantioselective Synthesis of Cocaine C-1 Analogues using Sulfinimines (N-Sulfinyl Imines)
摘要:
The first examples of cocaine analogues having substituents (methyl, ethyl, n-propyl, n-pentyl, and phenyl) at the C-1 position of the cocaine tropane skeleton were prepared by heating sulfinimine-derived alpha,beta-unsaturated pyrrolidine nitrones. In the presence of the Lewis acid Al((OBu)-Bu-t)(3) the nitrones undergo an intramolecular [3 + 2] cycloaddition to give tricyclic isoxazolidines that were transformed in three steps to the cocaine analogues. In the absence of the Lewis acid, lactams were formed resulting from rearrangement of the nitrone to an oxaziridine. A novel Pd-and base-promoted rearrangement of methanesulfonate salts of isoxazolidine to bridge bicyclic[4.2.1]isoxazolidines was discovered.
Asymmetric Synthesis of Substituted Tropinones Using the Intramolecular Mannich Cyclization Reaction and Acyclic <i>N</i>-Sulfinyl β-Amino Ketone Ketals
作者:Franklin A. Davis、Naresh Theddu、Paul M. Gaspari
DOI:10.1021/ol9002948
日期:2009.4.2
Sulfinimine-derived, enantiopure N-sulfinyl β-amino ketone ketals on hydrolysis give dehydropyrrolidine ketones that on treatment with (Boc)2O/DMAP afford substituted tropinones in good yield.
Asymmetric Total Synthesis of (<i>S</i>)-(+)-Cocaine and the First Synthesis of Cocaine C-1 Analogs from <i>N</i>-Sulfinyl β-Amino Ester Ketals
作者:Franklin A. Davis、Naresh Theddu、Ram Edupuganti
DOI:10.1021/ol1017118
日期:2010.9.17
Sulfinimine-derived α,β-unsaturated pyrrolidine nitrones, on heating with Al(O-t-Bu)3, undergo a highly stereoselective intramolecular [3 + 2] cycloaddition to give tricyclic isoxazolidines, which are transformed in three-steps to give C-1 substituted cocaine analogs.