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New Nonplanar trans-Stilbenes Exhibiting Nematic Phases at Room Temperature.

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amino-I-propyne ( 4 ) adds (2aj with formation of (5)
(t = 12 days at 25 “C).
The structure of (5) (m.p. 90-91°C; yield 34%) was
proved by elemental analysis, mass, ‘H-NMR and IR
spectra (1880 cm- I).
appropriately substituted benzyl phenyl ketones, which
were prepared by the standard Friedel-Crafts acylation
procedure employinga phenylacetyl chloride and a benzene
derivative. The stilbenes ( I a) and ( I 6) were synthesized
from the ketones by LiAlH, reduction, dehydration with
These additions may, like the analogous carbene reactions,
proceed by a concerted (cheletropic)or a two-step mechanism[’]; investigations are in progress.
Received: March 12,1971 [Z 384 IE]
German version: Angew. Chem. 83,401 (1971)
[I] Investigations on Strained Cyclic Acetylenes, Part 2.-Part
1: see
PI.
[2] E. Winterjeldt, Angew. Chem. 79, 389 (1967); Angew. Chem. internat. Edit. 6,423 (1967); E. Winterfeldt, D. Schumann, and H. J . Dillinger,
Chem. Ber. 102, 1656 (1969).
[3] Z Takizawa, N . Obata, k: Suzuki, and 1: Yanagida, Tetrahedron
Lett. 1969, 3407; Y. Suzuki, N . Obata, and 7: Takizawa, ibid. 1970, 2667.
[4] T R. Oakes, H. G. David, and F . J . Nagel, J. Amer. Chem. SOC.91,
4761 (1969).
[ 5 ] A. Xiebs and H. Kimling, Tetrahedron Lett. 1970, 761.
161 T Eicher and G. Frenzel, 2. Naturforsch. 20b, 274 (1965).
[7] L. A. Paquette, T .
I
.
Barton, and N . Horton, Tetrahedron Lett.
1967, 5039; R . Gompper, A. Studeneer, and W Elser, ibid. 1968, 1019.
181 Review: H . Kessler, Angew. Chem. 82, 237 (1970); Angew. Chem.
internat. Edit. 9,219 (1970).
[9] See R. B. Woodward and R. Hofmann, Angew. Chem. 81,797 (1969),
particularly p. 858-862; Angew. Chem. internat. Edit. 8, 781 (1969).
New, Nonplanar trans-Stilbenes Exhibiting Nematic
Phases at Room Temperature
By William R. Young, Arieh Aviram, and Robert J. Cox“’
In 1969, Kelker and Scheurle reported the preparation of
N-(p-methoxybenzy1idene)-p-n-butylaniline,which exhibits a nematic mesophase between 20 and 41 ‘C[’’. This
compound suffers, however, from two drawbacks : it is
yellow and it hydrolyzes in the presence of ambient
moisturec2].
We have now investigated some trans-stilbene derivatives
that are unique among the nematogenic ~ Z O [ a~ ~~ o, x y [ ~ ’ ,
azomethineL3’, nitrone14], and ~tilbene[~~*]
compounds
in combining an inherently colorless appearance with a
relatively high degree of resistance toward moisture, long
wavelength ultraviolet light, and oxygen.
In an earlier publication[*] we postulated that the high
melting points of trans-stilbene and related para-substituted derivatives is a consequence of the planar configuration of these molecules[61,and it was hypothesized
that nonplanar, low melting nematic materials could be
prepared by the introduction of small, globular substituents in the alpha, beta, or ortho positions of the
molecule. The use of alkyl substituents in the para positions might also prove beneficial, as has been demonstrated
for the azomethines“’.
We have synthesized a series of trans-stilbene derivatives
( I ) . The precursors for all of these compounds are the
[*] Dr. William R. Young and Arieh Aviram B.S.
IBM Watson Research Center
P. 0. Box 218
Yorktown Heights, New York 10598 (USA)
Robert J. Cox M.S.
IBM Research Laboratory
San Jose, California 95114 (USA)
410
[a]
[b]
[c]
[d]
n-C,H,
n-C,H,
n-C,H,
n-C,H9
n-C,H,
n-C,H,
n-C*H 1 7
2-methylpentyl
2-methylhexyl
n-CllH17
H
H
H
CH,
H
C1
CI
C1
CI
CI
H
H
CH,
H
CI
H
H
H
H
H
n-C,H9
n-C,H,
C1
C1
H
H
H
CH,
H
H
H
H
H
H
H
H
H
n
137
49
60
64
36
29
32
32 [c]
22 [c]
14
48
41
Nematic-isotropic transition temperature.
Monotropic transition.
On cooling, the nematic phase is indefinitely stable at 18°C.
Smectic-nematic transition temperature.
NaHSO,, and low temperature recrystallization.The methyl derivatives ( I c ) and ( I d ) were prepared from their
appropriate ketones in an analogous manner, except that
methylmagnesium iodide was employed as the reducing
agent. The chloro compounds (1 e) to ( I 1) were synthesized by reaction of benzyl phenyl ketones with phosphorus
pentachloride, followed by filtration through silica gel
and low temperature recrystallization.
Although additional corroborating experiments must be
pursued, it can be tentatively concluded from the properties of the compounds shown in the table that our
hypotheses are correct.
Two of the stilbenes, ( I h ) and (li), can be classified as
room temperature nematic materials. Although the former
substance is nematic at room temperature only in its
supercooled state, neither has crystallized after several
weeks at 18”C, even in a thin film. The methyl branch
may be detrimental to rapid crystallization. The stilbene
( l j ) , which is the only substance listed that contains two
alkyl moieties as the wing groups, is a normal liquid at
ambient temperatures and exhibits a smectic as well as a
nematic phase.
Quite large enantiotropic nematic ranges are exhibited
by (If) and ( l g ) , and even longer ranges can be obtained
by preparing binary mixtures. A formulation containing
60 mole-% (If) and 40 mole-% ( l g ) , for example, has a
nematic range of 8 to 59 “C.
All of the stilbene compounds (2) are white, crystalline
solids at appropriate temperatures. The short wavelength
cutoff of these materials is exemplified by the ultraviolet spectrum of stilbene ( I g ) in ethanol, h,,, = 305 nm
( ~ ~ 000),
2 8 hcutoR=350 nm. Each one of the nematic
phases observed as a colorless, turbid, mobile phase in a
capillary tube could also be detected under a polarizing
microscope equipped with a Mettler Hot/Cold Stage.
Angew. Chem. internat. Edit.
Vol. 10 (1971) 1 No. 6
Several of the compounds have been employed in their
nematic states in the following experiments: the observation of dipole-dipole splitting in the nuclear magnetic
resonance spectrum of a solute molecule dissolved in a
nematic hostr7,*];the reproduction of the dynamic scattering effect, described by Heilmeier and co-worker~[~],
when suitable dopants are introduced into the cell[’o1;
the appearance of color bands, characteristic of a
cholesteric mesophase, upon addition of cholesteric compounds to the mesomorphic stilbenes.
They are, in addition, potentially useful as stationary
phases for gas chromatography[“] and as solvents in
infrared[”], ultraviolet/visible“”, and ESR[13’ spectrometric experiments.
Received: January 8, 1971 [Z 356 IE]
German version: Angew. Chem. 83, 399 (1971)
[I] H . Kelker and B. Scheurle, Angew. Chem. 81, 903 (1969); Angew.
Chem. internat. Edit. 8, 884 (1969).
[Z] I . Teucher, C. M . Paleos, and M . M . Labes, Mol. Cryst. and Liq.
Cryst. 11, 187 (1970).
[3] W Kast in: Landolt-Bornstein Zahlenwerte und Funktionen. 6th
Edit., Springer, Berlin 1960, Vol. 11, Part 2a, p. 266.
[4] W R . Young, I . Haller, and A . Auiram, IBM J. Res. Develop. IS,
41 (1971).
[S] W R . Young, I. Haller, and A. Auiram, Abstr. of Papers, 161st
Nat. Meeting Amer. Chem. SOC.,1971.
[6] J . M . Robertson and I. Woodward, Proc. Roy. SOC.A 162,568 (1937).
[7] A. Saupe, Angew. Chem. 80, 99 (1968); Angew. Chem. Internat.
Edit. 7, 97 (1968).
[8] C. S . Yannoni, personal communication.
[9] G. H . Heilmeier, L. A. Zanoni, and L. A . Barton, Appl. Phys. Lett. 13,
46 (1968).
[lo] W R. Young, A . Aviram, and R . J . Cox, unpublished results.
[I11 H . Kelker, 3. Jainz, J . Sabel, and’H. Winterscheidr, Abst. of
Papers, Third International Liquid Crystal Conference, 1970, Abstract
No. S 9.11.
[l2] R.A. Leuenson, H . B . Gray, and G.P. Ceasar, J. Amer. Chem. SOC.
92, 3653 (1970).
[I31 A. Carrington and G . R . Luckhurst, Mol. Phys. 8,401 (1964).
The third of these steps has already been ~ l a r i f i e d [ ~We
*~!
now report on the preparative realization of this biogenetic
scheme by synthesis of erythrinane ( 5 ) from the benzyltetrahydroisoquinoline ( 3 ) .
Oxidation of N-mesyl-5’-methoxynorreticuline
( 3 ) with
VOCl,[51 in CH,CI, gave the morphinandienone (8) in a
yield of 34%, which is very high for an oxidative morphinan
ring closuref6][m. p. 235-238 “C; IR bands in KBr, 1665,
1640, 1615 cm- (dien~ne~’’)]
(ring closure b). Under very
mild catalysis by BF,/ether at 20°C, which precludes an
apomorphine rearrangement, (8) is rearranged to the isomeric biphenyl derivative (10) (ring opening a)(*]. This
compound absorbs 1 mol of H,in presence of Pt/charcoal
in methanol and in the NMR spectrum (CDCl,, TMS= 10)
shows three aromatic (T= 3.60, 3.45, and 3.14) and two cisolefinic protons (7 =4.63 and 3.76 ; J = 10.5 Hz). Catalytic
hydrogenation of (10) and subsequent demesylation by
lithium in liquid NH, leads to the secondary amine ( 9 )
which can be condensed oxidatively by K,[Fe(CN),] in
5% KHCO, solution to give 14-methoxyerysodienone ( 5 )
(ring closure c). The structure of ( 5 ) is proved by the follow-
“d
(3), R
(4). R
=
OCH,, R‘ = MS
= H,
R’ = CH3
Organisch-Chemisches lnstitut der Universitat
44 Miinster, Orleans-Ring 23 (Germany)
Angew. Chem. infernat. Edit.
Vol. 10 (1971) 1 No. 6
(5), R
(6). R
= OCH3, R ’ =
H
= H, R’ = OCH3
(7), R , R’= H
I
VOCI,
(34%)
OH
OH
(9)
(8)
OH
t)H
MS = SO&H3
[*j Prof. Dr. 8. Franck and Dip1.-Chem. V. Teetz
0
bH
By feeding with radioactively labeled precursors Barton
et
recently provided a proof that the skeleton of the
Erythrina alkaloids (which have curare-like action) as well
as that of morphine and other alkaloids is derived from a
benzyltetrahydroisoquinoline(1). The conversion of ( I )
into (2) must occur in three steps:
1. Ring opening “a” in (1) ;
2. Ring closure “b” in (2) ;
3. Ring closure “c” in (2).
H3C0
H3C0
Model Reactions for the Biosynthesis of Erythrina
Alkaloids1’]
By Burchard Franck and Vo’otkerTeetd’]
+ H3C0
HO
fro)
ing analytical findings: IR spectrum in KBr: 1680, 1655,
and 1620 cm-‘ (dien~ne[’*~]);
NMR spectrum (CDCl,,
TMS=IO): ~=4.28,3.79, and 3.77 (H on C-4, C-I, and
C-17[’]); UV spectrum in methanol: h,,,=216, 238, and
280 nm. These IR and UV data rule out the structure of
the isomeric 4-methoxyerysodienone (6) which could have
arisen by condensation of the nitrogen with the more
highly substituted phenol portion.
The ready availability of the morphinandienone (8) (see
below) is decisive for this new erythrinane synthesis with
average yields of 60% per step. In view of these results
norreticuline ( 4 ; R’= H) can be considered as biosynthetic
41 1
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