.beta.-Proline analogs as agonists at the strychnine-sensitive glycine receptor
摘要:
3-Carboxy-3,4-dehydropyrrolidine was found to bind with affinity equal to that of glycine in a [H-3]strychnine binding assay. Simple substitution of the 1-, 2-, 4-, or 5-position resulted in marked loss of affinity. A decline in affinity was also found upon enlargement, contraction, or saturation of the 5-membered ring. However, beta-proline and azetidine-3-carboxylic acid retained significant binding affinity. Despite its good affinity in [H-3]strychnine binding, 3-carboxy-3,4-dehydropyrrolidine showed only weak agonist activity in intracellular recordings of cultured murine spinal cord neurons. This apparent lack of correlation between binding and functional results is discussed in light of the current models of the strychnine-sensitive glycine receptor.
Regioselective 6-<i>Endo </i>Cyclization of 5-Carbomethoxy-5-hexenyl Radicals: A Convenient Synthesis of Derivatives of the 1-Azabicyclo[2.2.1]heptyl System
作者:Ernest W. Della、Chris Kostakis、Paul A. Smith
DOI:10.1021/ol990557n
日期:1999.8.1
[GRAPHICS]Ring closure of the 5-carbomethoxy-5-hexenyl radical is governed largely by the polar effect, and as predicted by frontier molecular orbital considerations, endo cyclization predominates, leading to cyclohexyl rather than cyclopentyl- based products, In cyclization of the corresponding beta-ammonio species 18, stereoelectronic effects do not distinguish between attack of the radical center at C3 or C4, each of which represents a 5-exo ring closure. The radical 18 is found to cyclize with great rapidity and with high stereoselectivity to give bicyclo[2.2.1]heptane products in accordance with expectation based on polar effects; this transformation represents an excellent entry to the physiologically important bicyclic ester 17.