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Influence of the Distance of the Proline Carbonyl from the and Carbon on the 13C Chemical Shifts.

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30 min. After hydrolysis, the product is extracted and dried.
Sollcnt removal leads to the nearly pure epoxide which can
be purified chromatographically (SOzMcrck, ether/pentane).
Received: May 2, 1975:
revised: June 9. 1975 [Z 275 IE]
German version: Angew. Chem. 87. 709 11975)
CAS Registry numbers
( 2 ) . R ' = R ' = H . ~6051-03-7:17). R ' = - H , R ~ = c H , . 5 m i - o 4 - x :
121. R ' = Ef. R 2 = i r C h H 56051-05-9: (21. R ' = R 2 = CII,. 56051-06-0:
i2J. R , =CH,. R Z =C,H,, 56051-07-1 : 12). R ' R * = -(CH2)s-,
56051-08-2:
i . 5 ~ 1 ) . 56051-09-3: i s h i . 56051-10-6;( 5 0 . 56051-1 1-7: i c d ) . 56051-12.8;
(51,).56051-13-9: i s 0.m 5 i - 1 4 - 0 : /.igj. s6nsi-i5-i : irj).m s i - i 6 - 2 :
i s h i . s6os1-I7-3 : i I / .5 6 m i -I8-4: ( ~ I I I 5) .6 ~ 1 - 1 9 - :5 (sll),
s m Z i -20-x:
f s ( J ) .56114-35-3: i h r l J . 56144-90-2; i 6 h l . 56144-91-1. ( h i . / . 56144-92-4:
i h l i i . 56144-93-5; ( ~ C ' J . 56144-94.6: (6 r l , 56144-95-7; i n n ) . 56143-96-8:
, J .
i n l i 56144-97-9:
~
( h i ) . 56144-99-1: i6Jli). 56t4~-00-7; (,qil). 96-09-3:
{S'hj. 4436-12-0: iH('). 17328-74-4: ih'd). 56051-21-9:
i,vl,i. 56o51-27-n: (,Y { I . s m - 2 7 - 1 : ~ H ~ 101~2-58-6:
~ J .
i x ~ l i .56051-23-2: i R i i . 56051-25-3: i s I / .s6051-26-4:
iS'hI. 37545-92-9: I X I ) . 56051-27-5: i 8 i 1 1 ) .53898-16-1 :
iI J . R = R~ = H. son-00-0: i~ 1 R. = H , R' = C H .~.
75-07-(1,
( I / . R'=H.R'-ri-C,H,,,
66-25-1: ( 1 ) . R ' = C H , . R ' = C H , .
67-64-1;
( I ) . R ' . - C I I , . R z = C 2 H I . 78-9.1-7: (1,. R I R ' = -(Cll2),-.
108-94-1:
inethancsclenol, 6486-05.1
We have studied this "proximity effect" systematically by
measuring the I3C-NMR spectra of a few conformationally
well-defined cyclic peptides of proline['' including data already
available in the literature. While the coplanar acyl-proline
bond is usually trans, but in cyclic and polyproline peptides
is also present in the cis conformation, no energy barriers
exist for the geometry of the structural element C D X 7 C=O. so that the distance betwecn C=O and C-8 described
by the dihedral angle 0[31(see Fig. 1) can be of varying size.
As shown in Figure 2 the chemical shift difference of the
y and p carbon resonances of proline, A6,p, at least between
0 and cu. 100" is a linear function of the absolute value
of 0.
There is a distinct difference between the slopes of the
curves for the cis- and the trans-XPro peptides. Whether the
linear relationship continues up to 8= 180" will be tested
on further rigid proline derivatives. The equations of the curves,
calculated by the method of least squares, are:
for the cis-series: A6k,=0.081]8l +2.47,
and
for the trans-series: A6py =0.036 181 +0.73
W Dur?~onrand A . Kuief, Angew. Chem. 87, 347 (1975): Angew. Chem.
internal. Edit. 14. 350 (1975)
[I] Methyl butyl selcnide. b.p.0 C 1 torr. Dimcthyl cclcnide' h p 58 C, 760
torr.
131 C . E. C o i i f ~J.~Chcin.
.~
Soc. 1953. 2839.
[4] VPC. IR. N M R , mass spectra are identical with an authentic sample
prepared from heptylidenetriphen).lphosphoranc and cyclohexanone.
[I]
Influence of the Distance of the Proline Carbonyl from
the fl and y Carbon on the 'C Chemical Shifts
By Ignacy Z . Siemion, Theodor Wieland, and Karl-Heinz
Pook[*]
3C-NMR spectroscopy can supply useful information
about the cis-trans isomerism of the acyl residue (X) bound
to nitrogen in proline-containing peptides, since the signals
of the p-C and y-C atoms are more separated in cis-XPro
than in truns-XPro[". Information can also be obtained, of
course, from the effect of the proline carbonyl orientation
on the chemical shift of the p-C resonance['].
R'- C -
=
X
6
Fig. I . Dihedral angle $I and e=($I-60")= O=C-C'-CB
tides.
in
proline pep-
[*] Prof. Dr 1. Z . Siemion [ '1 (Alexander-von-Humboldt Fellow)
Chemischcs Institut der Universitcit
Wroclaw (Poland)
Prof. Dr. Th. Wieland
Chemischcs lnstitut fir medizinische Forschung, Ahteilung NatnrstoffChemic
69 Heidelberg (Germany)
Dr. K.-H. Pook
Analytisches Lahoratorium dcr Fa. C . H. Boehringer Sohn
6507 lngelhcim (Germany)
[ - ] Author t o whom all correspondence should he addressed.
702
Fig. 2. Linear dependence of thedifference in chemical shifts of the "C-NMR
signals of p-C and y-C of proline (A&,[+) with dihedral angle e=($-60").
For explanation see text.
The @-valuesin the compounds ( I ) to ( 4 ) were measured
on Dreiding models constructed with the aid of data from
the literature[4,51. The values for polyproline 1 ( 5 ) [ ' ] , polyproline IT (7)"'. cyclo(Gly-L-Pro), i6)''l and gramicidin S-A
(8)["l were calculated from published data. The points a,
b, c, and d in Figure 2 refer to 13C-NMR values measured
on antamanide-Na+ in CD,OD and are in good agreement
with Putel's['"] measurements in CD3CN. Of the previously
unassigned signals for the y-C atoms of the four proline rings
it could be concluded that the two occurring at high field
(23.39 and 23.91 ppm) are due to the Pro-8 and Pro-3 moieties,
since, according to X-ray structure analysis[' 'I, these are cisXPro residues in which the y-C signals occur at higher field
than in trans-XPro (see Refs. [ I , 121). Accordingly, the
resonances at 25.87 and 26.29 ppm must be due to thc two
trans moieties Pro-7 and Pro-2. Of the four p-C signals at
29.46, 29.64, 33.10, and 33.74 those at higher field correspond
to the trans-XPro moieties Pro-7 and Pro-2, the lower ones
to Pro-3 and Pro-8. The Alip,-values of the four proline residues
are listed in Table 1 together with the €)-values measured
by X-ray structure analysis on the antamanide Li+complex 3!
Table 1. Chemical shifts 6 of the "C-NMR signals (in ppm. rel. to TMS) of the
defined peptidcs of proline. a -d see t c h t .
No.
Compound
B-
and 5!-cdrbons of proline and the dihedral angle
SCP
Solvent
e of a few conformationally
A6.1~
6C'
0
["I
ci.s-Series
(I
cyclo-Anthranoyl-L-prolyl [a]
)
(2)
cyclo-L-Prolyl-L-prolyl
CD,OD;'D,-DMSO
(I:I)
CD,OD D,-DMSO
26.78
24.15
2.63
28.39
23.86
4.53
-
29.70
22.65
4.61
4.30
7.05
ca. 45
30. I 1
22.32
7.79
0
30
(I:I)
(3)
D,O
DMSO [ I ]
CD,OD/D,DMSO
cyclo-Tri-L-prolyl
(I:I)
(4)
cyclo-L-Prolyl-D-prolyl
(5)
Polyproline I
Antamanide-Na
a Pro4
b Pro-3
(X)
Polyproline II
Grdmicidin S-A
(Y)
cyclo-Homoanthranoylprolyl
(7)
9.70
H z O [II
- 60
(L-Pro-)
98
+
c Pro-2
d Pro-7
cyclo-(Gly-L-Pro),
(6J
CD30D/D,-DMS0
( I :I )
[Ill
[Ill
CD,OD
CD,OD
33.10
33.74
23.39
23.91
9.7 I
9.83
85
88
CD30D
CD,OD
CD,CN/CDCI,
(I: I )
H2O "I
DMSO [9]
CH,OH [9]
29.64
29.46
26.29
25.87
3.35
3.59
I .3(1
79 [Ill
85 [II ]
10
[a]
3.30
5.10
4.80
CD,OWDMSO
31.41
-.
7 7 . I6
8.25
86
- 100
7.5
~-xo
(I:I)
[a] New compound: m p. 209-211"C:C,,H,,NZ0,(216.23),obs.
m/e=2I6(M-).
We have used the above observed relationship for determining the conformation of the previously undescribed cyclohomoanthranoyl-L-prolyl ( 9 ) (m.p. 260-261 "C; C1,H,,N,O,
(230.25), observed rn/e=230 (M+)).
Compound ( 9 ) can be
constructed with the aid of Dreiding models in two stable
conformations, one with 8=30", the other with 0 between
70 and 100". We found A6,~=8.25 and therefore, using the
plot for cis-XPro in Figure 2, we assign a value of 8=75--80"
to the cyclic peptide ( 9 ) .
Aliphatic Thioacyl Chlorides.
Preparation and Properties
By Giinther Seybold[*]
Thioacyl halides (2) are of great importance in preparative
organic chemistry as thioacylating agents. While the aromatic
compounds have been described in numerous publications,
all previous attempts to synthesize the aliphatic representatives
of typeR--CS--Cl have so far failed. Only a few perfluorinated
compounds have been prepared"!
We have found that addition of hydrogen chloride to the,
now, readily accessible thioketenes[21 provides a simple and
direct route to this class of compounds.
Received: July 16, 1975 [Z 276 IE]
German version: Angew. Chem. 87.711 (1975)
CAS Registry numbers
i l l . 1 ~ 7 7 - 3 4 - 4 (; 2 ) . 19943-27-2: ( 3 ) . 227742.9: 141, 53990-72-0:
iCj. 251'91-13-3: (6). 56144-84-4: 171, 25213-33-6: i X j . 113-73-5:
1 9 ) . 56144-85-5: antamnnide-Na+. 14344-26-8
[I] See r . g . D. E . Dormuii and F. 4 . Bocey. J. Org. Chem. 38, 2379 (1973).
and literature cited therein.
mea.;urements were carried out by I%! Pr!..u in Dr K - H . PooL's
laboratory Wc wiqh to thank him for his excellent work.
For a definition of the spatial parameters of the peptide chain w c
the IUPAC-IUP Recommendation in Biochemistry 9, 3471 (1970).
I. 2. Sirniion, Liebigs Ann. Chem. 74X, 88 (1971).
Ch. M . Deher, D. .4. Torrhiu. and E. R. Blour, J. Am. Chem. SOC.
Y3. 4893 (1971).
W Puub and U . Shmurli, Nature 198, I165 (1963).
P. M . Cowan and S. McGnriii, Nature 176, 561 (1953).
I
! Mndison, M . Arreyi, C . hl. Dubrr, and E. R. Blouf, J . Am. Chem.
SOC.96, 6725 (1974).
W A. Gibbons, J . A. Soyii, A . Stern, L. C. Crriiy, and L. F . Johrisoii,
Nature 227, 840 (1970).
D . J . Pntrl. Biochemistry 12, 667 (1973).
I . L. K a r f e , J. Am. Chem. Soc. 96, 4000 (1974).
G. R. Bedford and P. J. S a d h , Biochim. Biophys. Acta 343, 656 (1974).
The values obtained on X-ray structure analysis of the Na+-complex
are in complete agreement with those obtained with the Li+-complex.
111 The
[3]
[4]
157
[6]
[7]
[XI
[Y]
[lo]
[I I]
[IZ]
[I31
Aiigew.
Chcm inrcwiar. Edit. / Val. 14 f 1975) i N o . 1 0
When hydrogen chloride is passed into solutions of the
thioketenes (1 a ) - ( ] c) at -80°C the violet thioketene color
disappears within a few seconds and yellow to orange-red
solutions of the thioacyl chlorides (2a)-(2c) are formed.
( 1 a ) also addschlorine under the same conditions with quantichlotative formation of the 2-chloro-3,3-dimethylthiobutyryl
ride ( 3 ) .
[*] Dr. G. Seybold
Institut fur Organische Chemie der Universitit
8 Miinchen 2, Karlstr. 23 (Germany)
Present address:
BASF AG. Farbenforschung
6700 Ludwigshafen (Germany)
703
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carbonyl, chemical, 13c, proline, carbon, influence, shifts, distance
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