A. Abdel-Aziz, S. A. Bialy, F. Goda
Oct 18, 2004
Citations
0
Influential Citations
10
Citations
Journal
Tetrahedron Letters
Abstract
Abstract An enantioselective synthesis of sterically congested 1,2-di- tert -butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans -1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)- trans -4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert -butyl or 1-adamantyl cuprates to provide (4 S ,5 S )-4,5-di- tert -butyl and (4 R ,5 R )-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15 , respectively. Furthermore, N -acetyl 4,5-di- tert -butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones 16a , b were enantioselectively deacetylated using a catalytic oxazaborolidine system to provide enantiopure 1- p -tolylsulfonyl-4,5-di- tert -butyl-2-imidazolidinones 12 and 19 and 1- p -tolylsulfonyl-4,5-di-(1-adamantyl)-2-imidazolidinones 18 and 20 , respectively. Finally, N - p -tolylsulfonyl-2-imidazolidinones 12 and 15 were treated with 30 equiv of Ba(OH) 2 ·8H 2 O to achieve ring cleavage and to provide (1 S ,2 S )-1,2-di- tert -butylethylenediamine 3 and (1 R ,2 R )-1,2-di-(1-adamantyl)ethylenediamine 4 .