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7
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2]
[
[
[
[
2
[3]
the recently discovered human melanocortin receptors, we
5
need a series of hitherto unknown conformationally con-
3
[
*] Dr. V. A. Soloshonok, Prof. V. J. Hruby, C. Cai
Department of Chemistry
1
[
[
The University of Arizona
36] Complexes 1 ´ 3ClO
4
and 2 ´ 4ClO
4
were prepared as previously
1
306 E. University, Tucson, AZ 85721 (USA)
[
28]
III
IV
described.
The Mn (Mn
)
3
complex 1 ´ 3ClO
4
was prepared by
Fax : (1)520-621-4964 (V.A.S)
IV
one-electron reduction of the (Mn
) complex 2 ´ 4ClO by either its
4
4
Fax : (1)520-621-8407 (V.J.H)
bulk electrolysis in acetonitrile (method A) or by its reaction with
28]
1
.2 equiv of Me
3
(tacn) (method B).[
[
**] This work was supported by grants from the U.S. Public Health Service
Grant DK 17420) and the National Institute of Drug Abuse (DA
6284 and DA 04248). The views expressed are those of the authors
[
37] All reactions were run in 2 mL solutions of CH
chemicals were of reagent-grade quality and used as received.
Aqueous H stock solution (50% w/w, Aldrich) was standardized
with KMnO and used directly or as diluted with acetonitrile.
38] 2% H 18
Inc.
3 2
CN/H O at 228C. All
(
0
2
O
2
and not necessarily those of the USPHS.
4
18
16
[
2
O
2
(91 Æ 1% O, 9 Æ 1% O) was purchased from ICON,
Supporting information for this article is available on the WWW under
http://www.wiley-vch.de/home/angewandte/ or from the author.
2172
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