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New Synthesis of Heterocycles by means of Isocyanides.

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tion occurs slowly at room temperature, but in one minute
at 75°C even in absence of a catalyst.
H@
0-C=NI,
xa
R,
HO'
-
/CO-NHR~
R-C-C+
N-RZ
8
1
R'
(2)
R'
( 1)
=H
x
=R~-COO
/CO-NHR2
c=c,
N - ~2
R3-C6
-
R,
,CO-NHR2
S-v
o /N-R~
R~-CO
(4)
(5)
1
R'=BrCH?
The fission of the signals of two olefinic protons in the
ratio 1:1 in the spectrum of (2) then accords with expectation.
The 'H-NMR spectrum of the dimers of ( I ) contains
signals for only two olefinic protons, at - 6.35 and - 6.55
ppm, together with signals of 28 other protons at higher
shifts; hence follows that the two bulky boryl groups are
bound to olefinic centers and, as expected, not to the
junction centers of the cycloaddition. However, the diene
components then cannot have structure (6) but must be
(c) -an indication that there is an equilibrium between
(b) and (c) in which the more stable (b) preponderates
greatly.
R~
1.9 I
R-C-c
PI
=N- R~
The 'H-NMR spectrum of ( I ) contains signals with the
following shifts from TMS (relative intensities in parentheses): s=O.7 to -1.6 (lo), -3.17 (2), -6.79 (2),and -7.50
(1);on general experience these signals can be ascribed to
the two ethyl groups, a CH, group, and two olefinic CH
groups. Reaction (1) is excluded by the CH, signal, and
similarly isomer (a) in equilibrium (2) can be excluded. (c)
is excluded because it is known that with boron the nuclear
resonance frequency of ortho-ligands is lowered (e.g., with
compounds C,H,BX, and C6F,BX,), so that the spectrum
shows the existence of only one ortho-olefinic proton, as in
(b). Moreover, a CNDO-MO calculation[" shows (b) to
be about 7 kcal more stable than (c).
YH3 C O - N H R ~
H2C=C -C'
*
0
R-c
CO-NHR~
9 - R '
N-R~
0
(3)
(6)
HX = HC1, H B r . R3-COOK
then to the acyl-carbon, yielding compounds such as (7)
(with hydroquinone/boron trifluoride). (7) easily splits
off hydroquinone, giving the ketene imine (8)I4J.
Lecture at Aachen on January 22,1971 [VB 287 IE]
German version: Angew. Chem. 83,447 (1971)
[I]We thank Dr. J. Fleischhauer, Aachen, for the MO data
H3C-CO-C=C=N-C(CH3)3
I
(CH3)3
NH-C
New Synthesis of Heterocycles by means of
Isocyanides
By H.-J. KabbeCg1
(8)
In the presence of approximately equimolar amounts of
boron trifluoride, oxetanes ( I b) prepared from aromatic
aldehydes and tert-butyl isocyanide split off isobutene and
pass into the cinnamonitriles (9).
Numerous aliphatic aldehydes and ketones, as well as
aromatic aldehydes, react with isocyanides in the presence
of catalytic amounts of boron trifluoride, to give 2,3-bis(alky1imino)oxetanes( I ) " ] :
Lecture at Tiibingen on January 29,1971 [VB 288 IE]
German version: Angew. Chem. 83,448 (1971)
These oxetanes are remarkably stable both thermally and
towards bases but can be cleaved by acids HX. This normally affords the P-addition products (2), but occasionally
unsaturated amides such as (3) are formed by isomerization[*'.
When the oxetanes ( I a) are derived from aldehydes their
reaction with carboxylic acids leads to acyl migration and
formation of a-(acy1amino)-P-hydroxyacrylamides( 4 ) ; if
bromoacetic acid is used as addend, hydrogen bromide is
split off from the tautomeric keto form ( 5 ) and the plactam (6) is obtainedc3].
Neutral, weakly acidic, or basic compounds HY add to
( I a) only under the influence of an additional acid and
[l]
[2]
[3]
[4]
H.-J. Kabbe, Chem. Ber. 102,1404 (1969).
H . - J . Kabbe, Chem. Ber. 102, 1410 (1969).
H.-J. Kabbe and N . Joop, Liebigs Ann. Chem. 730,151 (1969).
H . 4 . Kabbe, Chem. Ber. in the press.
Rheological and Boundary Layer Problems
in Printing
By W Kunz"
All printing processes involve the transference of printing
ink onto substrate and, at least in the classical processesletterpress, offset, and gravure printing- interaction takes
[*] Dr. H.J. Kabbe
Farbenfabriken Bayer AG, Chemisch-wissenschaftliches
Laboratorium, Pharma
56 Wuppertal-Elberfeld (Germany)
424
[*] Dr. W. Kunz
Burda GmbH, Forschungsleitung
76 Offenburg, Postfach 360 (Germany)
Angew. Chem. internal. Edit. / Vol. I 0 (1971)
No. 6
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synthesis, mean, heterocyclic, new, isocyanides
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