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N-Haloborazines.

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For partial resolution the half-esters ( 8 a ) and (12a) are
dissolved in boiling ether and then treated with a one-half-equivalent of ( +)-z~-methylbenzylamine. The dextrorotatory
ammonium salts that crystallize are filtered ofr'"]; their optical
rotations in methanol amount to [!x];"=
+22.3" and +48.3",
respectively.
The optically active half-esters ( + ) - ( 8 a ) ([a];"= 22.2")
and (+)-( 12a) ([a];"=+ 53.9" (in acetone)) were liberated
from these salts by 2 N H2S04. Hydrolysis of these half-esters
in the manner described above afforded the optically active
tetrabromo alcohols (+)-(Xb) ([a];'= 14.4") and (+)(12b) ( [ ~ ( ] 6 ~ = 9 3 .(in
0 ~acetone)).
As previously found for the compounds ( 4 a ) and (4b)12],
the height of the energy barrier to rotation cannot be determined by NMR spectroscopy for ( K a ) , ( 8 b ) ,(12a),or (12b);
the peaks for the diastereotopic protons and methyl groups
show no coalescence up to 140°C, so that at most a minimum
value of 22-- 23 kcal mol- ' can be given for the energy threshold. The barriers can also not be determined by polarimetry.
Solutions ofthe butadienes(+)-(8a), ( + ) - ( K b ) ,(+)-(12a),
and (+)-(12b) in DMSO proved stable: no reduction in
the initial optical activity could be established after several
days at room temperature or after 8 hours at 80°C.
+
+
Received: July 10. 1975 [ Z 286 IE]
German version: Angew. Chem. 87. 715 (1975)
CAS Rcgistry numhcrs
(4U),54445-67-9. ( 4 h ) . 54445-66-8: [ J J . 13601-86-0: / 6 J . 6139-61-3:
17). 56391-19-6: (?)-(8u/~
56404-32-1 ; ( + ) - ( 8 u ) . 56391-20-9:
( i I - ~ X U~) 1 1 .56420-99-6: ( k ) - / S ' b ) . 56391-21-0: ( + ) - [ , ? h i . 56391-22-1 :
i Y i . 115-19-5: i l l ) ) , 56391-23-2: f l l j . 56391-24-3:
( i ) - ( / ? u ) . 56391-25-4; ( + ) - ( l Z a ) , 56391-26-5: ( + ) - ( l a ) salt, 56421-00-2;
( k )-/ / ? h i . 56391-27-6: ( + ) - / P / J56391-28-7
/.
[I]
L2]
131
141
[5]
161
173
[XI
[9]
[In]
G. Kdbrich, A. Munnschrech. R. A. M i s r u . G. Riasmunn, M . Rosnrr,
and W Zundorj, Chem. Ber. 105. 3794 (1972); G. Kiihrich, B. Kolh.
A . Munnschrrck, and R. A. Misru, ihid. 106, 1601 (1973).
M. R6siier and G. Kiihriclz, Angew. Chem. 86, 775 (1974); Angew.
Chem. internat. Edit. 13, 741 (1974).
H . - 0 . Biidrckrr, !L Jonos. B . Kolh. A . Mamirihrrck, and G. K i i h r i ~ h .
Chem. Ber. /OX, in press.
H:O. Bijdcder, Dissertation, Technische Universitat, Hannover 1975.
The structures of all the new compounds were established by UV,
IR, NMR, and mass spectra and by correct elemental analyses. The
constitutional idcntity of the racemic and optically active substances
was confirmed by spectral comparison.
L. Bruridsmu: Preparative Acetylenic Chemistry. Elsevier, Amsterdam
1971, p. 98.
M. D. Cnmeron and G. E. Bennrff, J. Org. Chem. 22, 557 (1957).
We assume for this and the following compounds an ionic bromination
mechanism and formation of (E,E)-tetrabromobutadienes.
By analogy with directions of A. G. Duoies, J . K r ~ i y o ~and
~ . L. W
f. SrtlomJ. J Chcm. Soc. 1957. 314X.
The enantiomeric levoiotatory salts can he obtained from the filtrate
by working up and addition of ( - )-a-methylbenrylamine.
Simultaneous dropwise addition of equimolar quantities
of CIN(SiR,), and BF,.O(C,H,), at - I O T , removal of the
volatile reaction products, and sublimation of the residue
at 70 "C/50torr affords 1,3,5-trichloro-2,4,6-trifluoroborazine
(1) in 50% yield, m.p. 97°C (after recrystallization from
pentane).
3 f3F3.0(CzIfs)z + 3 Clh(SiK3)2 + i l )
By Gernot Elter, Heinz-Jiirgen Kiilps, and Oskar Glernser[*]
Boron trichloride reacts with N-chlorobis(trimethylsily1)amine via elimination of trimethylchlorosilane to form hexachloroborazine"], the only N-halo derivative of borazine hitherto known[2'.While corresponding reactions of BCI, or BBr,
with N-bromobis(trimethy1silyl)aminedid not lead to the borazine system['r31, we have now been able to isolate two new
N-haloborazines as products of the reaction of boron trifluoride with N-halosilylamines :
[*] Prof. Dr. 0. Glemser, Dr. G. Elter, and Dipl.-Chem. H.-J. Kiilps
Anorganisch-chemisches Institut der Universitat
34 Gottingen, Tammannstrasse 4 (Germany)
[**I This work was supported by the Dcutsche Forschungsgemeinschaft
and the Fonds der Chemischen Industrie.
A n y n c . Chem. inrcvnur. E d i f . / Vol. 14 ( 1 9 7 5 ) / No. 10
6 K,SiE'
+ '1 ( C z H 5 ) z 0
During this reaction the nitrogen-halogen bond of the silylamine also undergoes some degree of cleavage since partially
N-silylated borazines B,F,N,CI,SiR, and B,F,N,Cl(SiR 3)2
could be detected as side products by mass spectrometry.
If gaseous BF, is passed at room temperature into a 25
solution of BrN(SiR,), in CCI, then analogous work-up of
the reaction mixture (repeated sublimation at 5OoC/10- torr)
affords 1-bromo-3,5-bis(trimethylsilyl)-2,4,6-trifluoroborazine
(2) in 16 yield, m. p. 50°C. No formation of an N-tribromoor N-dibromo derivative was observed; only B3F3N3(SiR3),I4l
could be isolated as side product.
( 1 ) and (2) form colorless crystals which react vigorously
with water; in the case of (1) hydrolysis proceeds with explosive violence. In the absence of moisture, however, the compounds can be stored indefinitely. Their compositions and
structures are verified by elemental analysis, and mass, IR,
Raman, and NMR ("B, "F, 'H) spectra. The IR gas phase
spectrum of ( I ) shows the principal vBN band (1466 cm--')
in the usual range for B-trifluorobora~ines[~l.
Received: July 4, 1975 [Z 287 IE]
German version: Angew. Chem. 87. 711 11975)
[I]
[2]
[3]
[4]
[5]
N. Wiberg, F. Raschiy, and K . H . Schmid, J. Organometal. Chem. 10,
29 (1967).
P. I . Poctzold, L. Anorg. Allg. Chem. 326, 47 (1963); J . C . Huostloor
and W L. Groeneceld, Inorg. Nucl. ('hem. Lett. 3, 597 (1967).
R. E . B a i l q and R . Wesf, J. Organometal. Chem. 4, 430 (1965).
G. Elfer, 0. Clmiarr. and W Herzog, Chem. Ber. 105. I 1 5 (1972).
A. Mrllrr, Organometal. Chem. Rev. 2, I (1967).
[2+ 21-Cycloaddition of Allenes to
N-Haloborazines [**I
+
Alkenes[**]
By Joachim H . Lukas, Arjan P. Kouwenhoven, and Frank
Baardrnan[*]
The small number of [2 2]-cycloadditions which probably
proceed via vinyl cations['] include the cyclodimerization of
2-butyne with addition of C1, to form 3,4-dichlorotetramethylcyclobutener2], the cyclodimerization of 1 -alkynes with addition of 2mol of HCI to give 1,3-dichloro-1,3-diaIkylcyclobutanel,], the cyclodimerization of allene with addition of 2 mol
and
of IlBr to yield 1,3-dibromo-l,3-dimethylcyclobutane~41,
the cyclodimerization of 2-butyne with AICl, to give the tetramethylcyclobutadiene-aluminum chloride
+
['I
Dr. J. H. Lukas, A. P. Kouwenhoven, and F. Baardman
Koninklijke/Shell-Laboratorium, Amsterdam (Shell Research B. V.)
Badhuisweg 3, Amsterdam (Netherlands)
[**I [2+2]-Cycloadditions, Part 1
709
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