163299-73-8Relevant articles and documents
Osmium-promoted dipolar cycloadditions with pyrroles: An efficient, stereoselective synthesis of 7-azanorbornanes
Gonzalez, Javier,Koontz, Jason I.,Hodges, L. Mark,Nilsson, Kent R.,Neely, Linda K.,Myers, William H.,Sabat, Michal,Harman, W. Dean
, p. 3405 - 3421 (1995)
A series of 7-azabicyclo[2.2.1]hept-5-ene complexes are prepared from [Os(NH3)5(η2-L)]2+ (L = pyrrole, l-methylpyrrole, 2,5-dimethylpyrrole, 1,2,5-trimethylpyrrole, or 1-(trimethylsilyl)pyrrole) and various dipolarophiles (e.g., acrylonitrile, methyl acrylate, α-methylene-γ-butyrolactone, dimethyl maleate, dimethyl fumarate, N-phenyl maleimide, cyclopentene-1,2-dicarboxylic acid anhydride, and (E)- and (Z)- methyl 3-(3'-pyridyl)acrylate). The cycloaddition is promoted by coordination of the pyrrole with [Os(NH3)5]2+ across C3 and C4, transforming the uncoordinated portion of the pyrrole nucleus into an azomethine ylide capable of undergoing 1,3-dipolar cycloadditions. The metal serves not only to activate the pyrrole ring but also to stabilize the resulting 7-azabicyclo[2.2.1]heptene ligands. A number of organic 7-azabicyclo[2.2.1]heptanes, including analogs of the alkaloid epibatidine, have been synthesized by this methodology. For the cases examined, the cycloaddition favors exo stereochemistry of the electron-withdrawing substituent when the pyrrole nitrogen is unsubstituted. Crystal structures have been determined for the complexes obtained from the reactions of pyrrole with N-phenylmaleimide (8a), 2,5-dimethylpyrrole with dimethyl maleate (13a), and 2,5-dimethylpyrrole with α-methylene-γ-butyrolactone (22a).
7-AZABICYCLO[2.2.1]-HEPTANE AND HEPTENE DERIVATIVES AS CHOLINERGIC RECEPTOR LIGANDS
-
, (2008/06/13)
-
