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Di(methylthio)carbene (Carbon Monoxide Methyl Mercaptal) from Di(methylthio)diazomethane.

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On sequential analysis of long-chain peptides, esterification
with methanol/HCI and N-trifluoracetylation following partial hydrolysis gave rise not only to dipeptides [5], but also
to many tri- and tetrapeptides, which can be gas-chromatographed by application of tempcrature programming. A gas
chromatogram of a partial hydi olysate of Leu-Leu-Val-Val
gave peaks for the three possible dipeptides, both possible
tripeptides, the unchanged tetrapeptide, and the two amino
acids. The fractions can be collecied and identified by mass
(2)
Y
-CsHs
-NR2
-OR
-00
17700
17700
18000
18850(W)
3.5
2.3
2.6
1.8
19950
19800
20 300
20700
17
16
16
11
spectrometry'
Received, July Znd, 1963
12 533/360 IE]
German version: Angew. Chern. 75, 724 (1963).
[I] F. Weygand, R. Geiger, and W Swodenk, Angew. Chem. 68,
307 (1956); F. Weygand, G. Klipprng, and D. Palm, Chem. Ber.
93, 2619 (1960).
[2] E. Stenhagen, Z. analyt. Chem 181, 462 (1961).
B-N=N-B
vmax [cm-ll
[3] Atlas MeR- und Analysentechiiik, Bremen (Germany). The
substances are introduced into thc ion-source by means of a
vapor lock (T04-oven), cf. G . Spiic,ller, C . Brunni, K . Heyns,
and H . F. Griitzmacher, Z . Naturl'orsch. 17b, 856 (1962).
[4] Spectra were also obtained from an N-TFA-pentapeptide
methyl ester.
[5] F. Weygand, A . Prox, E. C . Jorpnsen, R. A x i n , and P. Kirchner, Z . Naturforsch. 186, 93 (1963), and earlier papers.
22750
22750
21 350
24700
Di(methy1thio)carbene (Carbon Monoxide Methyl
Mercaptal) from Di(methy1thio)diazomethane
Table 2. Long-wave absorption maxima vmax of unsymmetrically
substituted azo compounds in dioxan.
~
~-
These regularities have been confirmed with numerous azo
compounds [2] and prompt us to assume that there are absorption increments which are characteristic for the substituents. The mechanism of the influence of substituents, i.e.
increase in the n-term or decrease in the n*-level, remains
a n open question. Investigations on solvatochromic effects
and dipole moments of symmetrically substituted azo compounds [2] will be reported later.
Received, July lst, 1963
[Z 535/368 IE]
German version: Angew. Chem. 75, 789 (1963).
By Doz. Dr. U. Schollkopf and Dip1.-Chem. E. Wiskott
Organisch-Chemisches Institul der Universitat Heidelberg
(Germany)
Tosylhydrazide undergoes addil ion onto CS2 in alkaline
solution to yield ( I ) , which m a y be alkylated successively
with methyl iodide to form the (isolated) monoester (2) and
thence the tosylhydrazone of S,S-dimethyldithiocarbonic
acid ( S ) , m.p. 151 "C.
TosNH-NH-C-S,O
CH3I
j
TosN tI-NR-C-SCH3
II
[I] Communication No. I1 on Inorganic Azo Comounds, Communication No. I : H. Bock and G. Rudolph, Chem. Ber. 94, 1457
(1961). Dimethyl phenylazophosphonate was first described by
F. Suckfiill and H . Haubrich, Angew. Chem. 70, 238 (1958).
[2] H. Bock, E. Baltin, J. Kroner, and G . Rudolph, unpublished
data.
Sequential Analysis of Peptides by Means of Mass
Spectrometry and Gas Chromatography
By Prof. Dr. F. Weygand, Dr. A. Prox,
DipLChem. W. Konig, and Dipl.-Chem. H. H. Fessel
Organisch-Chemisches Institut der
Technischen Hochschule Miinchen (Germany)
The relatively high vapor pressure of the N-trifluoroacetyl
(TFA) peptide esters [l] made it seem likely that it would be
possible to obtain mass spectra not only of N-TFA-dipeptide
esters [2] but also of even higher peptides. Numerous N-TFAtripeptide and N-TFA-tetrapeptide methyl esters were investigated [4] using a CH 4 Model mass-spectrometer [3].
An N-TFA-tetrapeptide for example, gave rise inter alia to
the following characteristic ions:
F3CCO-NHCHRCO-NHCHRlCO-NHCHR2CO-NHCHR3,
F3CCO-NHCHRCO-NHCHRlCO-NHCHR2,
F,CCO-NHCHRCO-NHCHRICO-NHCHR2
FsCCO-NHCHRCO-NHCHR',
H,
FBCCO-NHCHRCO-NHCHR'
FsCCO-NHCHR,
F3CCO-NHCHR t H,
HzNCHR3COOCH3 H.
+ H,
+
+
From these a n unequivocal sequential analysis of low oligopeptides is possible, even from mixtures.
Angew. Chem. internat. Edit. [ Vol. 2 (1963) No. 8
I1
CH,I
---+
TosNR-N=C(SCH3)2
Alkali
(3) R = H , ( 4 ) R = N a
On stirring with sodium hydride i n aprotic solvents, (3) yields
(4),which decomposes at approx. I20 "C into sodium toluenep-sulfinate and ( 5 ) . The latter splits off nitrogen and apparently yields (6).
_ . .
(6)
( 5)
On decomposing ( 4 ) in 1-morpholino-I-phenylethyleneor
ketene diethylacetal, the intermediate (6) can be trapped in
the form of the cyclopropane adducts (7) (32%, m.p. 60 "C)
or ( 8 ) (30 %, b.p. 114"C/12 mm).
HaCS, ,SCH3
i7)
H2.C
H&S\
/"\
,SCH,
C
/CsH5
-"\NAo
u
/ \ /OCzH5
(8)
HzC-C\
OCzH,
In addition, tetra(methy1thio)ethylcne [ I ] and trimethyl orthothioformate are also formed. Thc carbene does not undergo
addition onto cyclohexene (in diglyme); apparently its electrophilic nature is reduced by the Iwo sulfur atoms (owing to
their unshared doublets) to such an extent that it adds only
t o particularly electron-rich double bonds.
Received, July 5th. 1963
[Z 538/366 IEI
German version: Angew. Chein. 75, 725 (1963).
[I 1 Tetra(methy1thio)ethylene is also obtained when trimethyl
orthothioformate is treated with potassamide in ammonia. Di(methy1thio)carbene is considered to be an intermediate in this
reaction; cf. J . Hine, R . P . Buyer, and G . Hammer, J. Amer. chern.
SOC. 84, 1751 (1962).
485
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