Title
Novel Macrocycles from Metal-Catalyzed Oxidative Cyclizations of a,c-Biladiene Salts
Document Type
Article
Publication Date
1-1-1993
Abstract
From the metal-promoted oxidative cyclization of several 1,19-disubstituted a,c-biladiene dihydrobromide salts, a number of novel macrocycles were prepared. For example, the cyclization of 1,19-bis(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-octamethyl-a,c-biladiene dihydrobromide salt (10) with copper(II) acetate afforded copper(II) 20-((methoxycarbonyl)methyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-octamethyl-1,20-dihydroporphyrin (13) (39% yield), which, upon demetalation, yielded the metal-free 20-((methoxycarbonyl)methyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-octamethyl-1,20-dihydroporphyrin (14) (48% yield). With the substrate 19-((ethoxycarbonyl)methyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-octamethyl-a,c-biladi-ene dihydrobromide (15), the metal-catalyzed cyclization process produced copper(II) 20-(ethoxycarbonyl)-1-(2-(methoxycarbonyl)ethyl)-2,3,7,8,12,13,17,18-octamethyl-1,20-dihydroporphyrin (18) (27% yield) and copper(II) 20-(ethoxycarbonyl)-2-(2-(methoxycarbonyl)ethyl)-2,7,8,12,13,17,18-heptamethyl-3-methylidene-2,3-dihydroporphyrin (23) (19% yield). Upon demetalation of the copper dihydroporphyrin 18, 20′-(ethoxycarbonyl)-20-(2-(methoxycarbonyl)ethyl)-2,3,7,8,-12,13,17,18-octamethyl-20′-homoporphyrin (28) (16.5% yield) was isolated; demetalation of copper-(11) 20-(ethoxycarbonyl)-2-(2-(methoxycarbonyl)ethyl)-2,7,8,12,13,17,18-heptamethyl-3-methylidene-2,3-dihydroporphyrin (23) yielded the free base 20-(ethoxycarbonyl)-2-(2-(methoxycarbonyl)ethyl)-2,7,8,12,13,17,18-heptamethyl-3-methylidene-2,3-dihydroporphyrin (25) (24% yield). Using chromium (III) hydroxy acetate as the oxidant (in place of copper(II)), 1,2,3,7,8,12,13,17,18-nonamethyl-1,20-dihydroporphyrin (5) (55–62%) was obtained from the 1,2,3,7,8,12,13,17,18,19-decamethyl-a,c-biladiene salt 3. Mechanisms of macrocycle formation from a,c-biladiene salts, promoted by either copper(II) or chromium(III), appear to proceed via pathways closely resembling the electrochemical cyclization reaction of 1,19-dimethyl-a,c-biladiene salts. © 1993, American Chemical Society. All rights reserved.
Publication Source (Journal or Book title)
Journal of Organic Chemistry
First Page
6681
Last Page
6691
Recommended Citation
Liddell, P., Gerzevske, K., Lin, J., Olmstead, M., & Smith, K. (1993). Novel Macrocycles from Metal-Catalyzed Oxidative Cyclizations of a,c-Biladiene Salts. Journal of Organic Chemistry, 58 (24), 6681-6691. https://doi.org/10.1021/jo00076a030