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Infrared Rotatory Dispersion (IRD).

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at t=6.19ppm for the methoxycarbonyl group, a singlet
at T = 1.83 for the vinyl proton, and a multiplet at T = 2.45
to 3.13 ppm for the aromatic protons. The signal areas are
in the ratio 3:1:14. The characteristic IR spectra of (1)
exhibit the C=C stretching mode for 2,2-disubstituted
cyclopropenes at 1850-1900 cm- and for I-substituted
cyclopropenes at 1750-1800 cm- ' (see Table).
When R' = C,H,, small amounts of benzrelindenes (3)
are also formed. Use of high-energy UV light (h> 290 nm)
for the photolysis of (2c)-(2e)
in alkynes leads exclusively to ben~[eJindenes[~'
which are formed from ( I ) .
For example, the photolysis of (1c) (Hg high pressure
lamp, Pyrex filter: h>290 nm) gave an 80% yield of (3c)
via a 1,7 sigmatropic shift and subsequent rearomatization
(cf. also ref. [S]), i. e. under these conditions (1) underwent
direct rearrangement to (3).
An attempt was made to deduce information about ring
strain in ( I ) from the l J l , C - H coupling constant of (lb).
A 49.6% s component of the cyclopropene C-H bond was
calculated from lJ,,C--H=248 Hzl6.']. Studies on the effect
of spiro conjugation in ( I ) are currently in progress.
3-Methoxycarbonyl-2',3'-diphenyEspiro[cyclopropene1,I7-indene] (1d)
Compound (2d) (2.50 g, 8.5 mmol) is irradiated in methyl
propiolate (155 ml) for 2.5 h with the light from a Philips
HPK 125-W lamp (GW, filter: h>360nm). 85% of the
calculated amount of N2 were evolved within this time.
The propiolate was then distilled off at 4O0C/3Otorr and
the residue chromatographed on silica gel. Elution with
benzene/CHCl, (19:l) gave 1.70g of a brown oil, from
which 0.87g [29% yield based on reacted (Zd)] of (Id)
crystallized on using ether as a solvent; m. p. 118-119°C
after recrystallization from ether; IR: vC=C (cyclopropene)= 1775; vC=O = 1705; vC-H (cyclopropene)
particles participating in the transition. Effects are therefore predicted that are about four orders of magnitude
smaller than those recorded for electronic transitions.
Moreover, the components of an l
R spectral polarimeter
(Nernst glower, polarizer, thermocouple) have less favorable properties than the corresponding components of a
UV instrument. The search for anomalies has hitherto
been unsuccessful[''.
Previous measurements of the rotatory disperison of molecules covered only the near infrared down to 2500 cmHowever, the greatest and most informative effects are to
be expected in the range of skeletal vibrations. Our studies
in this spectral region with a single beam spectral polari-
meted3] having a sensitivity of 0.01" (at lo00 cm- 2 cmslit width, and 60% absorption) on both antipodes of
carvone ( I ) , a-pinene (21, phenylethylamine (3), and
show no measurable anomalies apart from the normal
drop in rotation with the wave number.
Received: November 3, 1971 [Z 560b IE]
German version: Angew. Chem. 84,215 (1972)
[I] Cycloalkene carbenes, Part I
[2] H. Diirr and L. Schrader, Angew. Chem. 81, 426 (1969); Angew.
Chem. internat. Edit. 8,446 (1969).
[3] H. E. Simmons and 7: Fukunaga, J. Amer. Chem. SOC.89, 5208
(1967); R. Hofmann, A . lmamura, and G. D.Zeiss, ibid. 89, 5215 (1967)
[4] E. ?: MacBee, G. W Calundann, and T Hodgins, J. Org. Chem. 31,
4260 (1966); G. Ege, Tetrahedron Lett. 1963, 1667.
[5] H.Diirr, L. Schrader, and H.Seidl, Chem. Ber. 104, 391 (1971).
[6] G. L. Closs, Advan. Alicycl. Chem. 1, 76 (1966).
[7] K . Mislaw, Tetrahedron Lett. 1964,1415.
Infrared Rotatory Dispersion (IRD)[**I
By Bernhard Schrader and Ernst-Heiner Korte"]
According to the theory of rotatory dispersion'" it is to be
expected that anomalous optical rotation can occur in the
infrared owing to molecular vibrations. The amplitude of
the anomalies is inversely proportional to the mass of the
[*] Prof. Dr. B. Schrader
Abteilung Theoretische Organische Chemie der Universitat
46 Dortmund-Hombruch, Postfach 500 (Germany)
Dip].-Phys. E. H. Korte
Institut fur Spektrochemie und angewandte Spektroskopie
46 Dortmund, Postfach 778 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft. We also wish to thank Dr. E. Steigner, Frankfurt, for the preparation of the antipodes of (4).
i [cm-'1
Fig. 1. a) IRD curve of 2 mol-% d-carvone ( I ) in Licristalm (5). layer
thickness 13 pm, NaCl windows; b) IR absorption spectrum corresponding to a); c) 1R absorption spectrum of d-carvone ( I ) , layer
thickness 50 pm.
Angew. Chem. internat. Edit.
Vol. 11 (1972)
NO. 3
Anomalies d o occur, however, when the molecules (1) to
( 4 ) are dissolved in a nematic liquid crystal. This optically
inactive mesophase is transformed into the optically active
cholesteric phase by addition of small amounts of chiral
We have found that a solution of 2 mol-%
d-carvone in Licristal@ ( 5 ) (eutectic mixture of the isomeric N-oxides of p-methoxy-p'-n-butylazobenzene)as a
13-pm layer between NaCl windows gives the rotatory
dispersion curve reproduced in Figure 1a with anomalies
having an unexpectedly large amplitude of ca. 7000deg/
mm. A corresponding curve of opposite polarity is recorded
for a solution of I-carvone. Solutions of (2), ( 3 ) , and ( 4 )
in ( 5 ) give curves having anomalies at the same frequencies
but of different magnitudes and forms. Solutions of (1) to
( 4 ) in a mixture of N-(p-methoxybenzy1idene)- and N-(pethoxybenzy1idene)-p'-butylaniline (6) produce similar
curves. The frequencies at which rotational anomalies are
observed agree with the IR absorption bands of the host
and (6) -while vibrations of the guest
molecules- ( 1 ) to ( 4 ) -are not seen in anomalies of the
dispersion curves (see Fig. 1).
We assume that the steric form of the chiral molecules
determines the pitch of the cholesteric phase. Anomalies of
the rotatory dispersion are to be expected when the effective wavelength in the cholesteric phase he,, (vacuum wavelength hop,divided by the refractive index n) is equal to the
pitch. The appearance of several anomalies in the IRD
curve can be explained by the fact that he,,= h,,Jn is equal
to the pitch for various values of h,, since n is subject to
wide variations in absorption bands.
Studies are in progress to determine in how far the sign
and degree of helicity of molecules can be ascertained with
the aid of this new effect.
Received: November 29,1971 [ Z 562 IE]
German version: Angew. Chem. 84,218 (1972)
[I]L. Rosenfeld, Z. Physik 52, 161 (1928); W Kuhn and K . Freudenberg: Drehung der Polarisationsebene des Lichts. Akad. Verlagsgesellschaft, Leipzig 1932; E. U . Condon, Rev. Mod. Phys. 9,432 (1937).
[2] 7: M . Lowry and C . P. Snow, Proc. Roy. SOC.(London) A 127,271
(1930); H . S . Gutowsky. J. Chem. Phys. 19, 438 (1951); L. R. Ingersoll,
Phys. Rev. 9, 257 (1917); H . J . Hediger and Hs. H . Gunthard, Helv.
Chim. Acta 37, 1125 (1954); H . R. Wyss and Hs. H . Giinthard, J. Opt.
SOC.56,888 (1966).
[3] E . H. Korte and B. Schrader, to be published.
[4] R. K u h n and P. Goldfinger, Liebigs Ann. Chem. 470, 183 (1929).
[5] G. Friedel, Ann. Phys. (Paris) t8, 273 (1922); A . D. Buekingham,
G . P . Ceasar, and M . B. Dunn, Chem. Phys. Lett. 3,540(1969); H . Stegemeyer and K . J . Mainusch, ibid. 6, 5 (1970); H . Stegemeyer. K . i.Mainusch, and E . Steigner, ibid. 8,425 (1971).
Amino Acid Analysis on the Picomole Scale["*]['I
By Norbert Lustenberger, Hans- Walter Lange,
.and Klaus Hempel"'
In an alkaline medium, amino acids (1) and pyridoxal (2)
undergo condensation to Schiff bases (3) which can be
converted into pyridoxyl amino acids of type ( 4 ) by catalytic reductionr2,3J or by reduction with sodium tetrahydrido-
['IDr. N. Lustenberger, Dr. H.-W. tange,
and Priv.-Doz. Dr. Dr. K. Hempel
Institut fur Medizinische Strahlenkunde der Universitat
87 Wurzburg, Versbacher Landstrasse 5 (Germany)
We are grateful to the Deutsche Forschungsgemeinschaft for their
support of this work and for a Grant to N.L.
Angew. Chem. inlernat. Edit. Vol. 11 11972) 1 No. 3
borate. We have found that pyridoxyl amino acids can be
detected extremely readily. After separation by column
chromatography, approx. 2 x
mol of an individual
pyridoxyl amino acid can be detected by spectrophoto-
N al
metry and approx. 5 x l o - " mol by fluorometric methods.
Reduction with radioactive NaBT, offers particular advantages since the tritiated pyridoxyl amino acids ( 4 ) can
be quantitatively determined on a picomole scale (1 x 10- l 2
In order to ascertain the sensitivity of this amino acid
analysis we have examined : a) the chemical reaction; b) the
isotope effect of the NaBT,-reduction of the Schiff bases
( 3 ) ; c) the separation of the pyridoxyl amino acids by
column chromatography ;as well as d) the possible methods
of determination.
a) The yields (Table) were determined by reaction of 25-pmol
portions of I4C-labeled amino acids of known specific
activity followed by column-chromatographic separation
from the pyridoxyl 14C-aminoacid. The highest yields were
obtained with 0 . 2 ~
solutions of pyridoxal in phosphate
buffer (pH=9.3). To the best of our knowledge pyridoxylcysteic acid, -glutamhe, -proline, and -hydroxyproline
have not previously been described.
The formation of pyridoxylprolines was unexpected since
the intermediacy of a Schiff base (3) can be ruled out in
this case. We suspect that the reaction proceeds tiia a keto
enimine intermediate[,. 'I. Cysteine and histidine d o not
give pyridoxyl amino acids of type ( 4 ) since the Schiff
bases of these compounds undergo spontaneous cyclization to products that cannot be reduced[']. Use of radioactive pyridoxal recommends itself in this case ; investigations are in progress.
b) Considerable isotope effects have been recorded[61 in
reactions with mixtures of hydrogen isotopes. For a given
series of pyridoxyl amino acids ( 4 ) we therefore determined
the yield and the 3H activity after reduction of the Schiff
bases ( 3 ) with NaBT, (spec. activity 10 mCi/mg-atom) and
calculated the specific 3H activities (Table) from these
results. Deviations from the value expected with no isotope
effect (10 mCi/mmol) lie within the limits of experimental
accuracy. The fact that no isotope effect was detected could
possibly have something to d o with our using NaBT,
diluted with NaBD,.
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rotator, dispersion, infrared, ird
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