Stereoselectivity catecholamines

Electron transfer from the chiral catecholamines to iron(III) in the FeTL or FeTD system proceeds stereoselectively only when the polypeptide matrices are predominantly in the a-helical conformation and the accessibility of the active sites is, at least partially, hindered. 

Hieble JP, Hehr A, Li YO, Ruffolo RR, Jr. Molecular basis for the stereoselective interactions of catecholamines with a-adrenoceptors. Proc West Pharmacol Soc 1998 41 225-228. 

The radiolabeled catecholamine tracer 6-[ F]fluorometaraminol (O Fig. 42.8b)) for mapping cardiac sympathic neutrons is another example for the introduction of F-fluorine by demetallation. It has been prepared by fluorination of 6-acetoxymercurio-N-t-BOC-metaraminol with acetyl hypofluorite followed by removal of the BOC group in about 30% radiochemical yield (Mislankar et al. 1988). In 2000, Ermert et al. have used an n.c.a. nucleophilic F-for-N(CH3)3 exchange on an N,N-dibenzyl protected ot-aminopropiophenone derivative, followed by a stereoselective reduction and deprotection step to prepare 4-[ F]fluorometaraminol in 15-20% radiochemical yield. Another four-step strategy was described by Langer et al. (2001). 

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