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Esterification of Carboxylic Acids with Aminoacetals.

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Carboxylic acid or
phenol
Acetal,
Pyridine-3carboxylic acid
(2)
CHzClz
22
Adipic acid
(2)
CHzCl2
22
1 1 13, I:
[%I
[ "cl
o-Hydroxyhenzoic acid
(2)
CHzCIz
Fumaric acid
(3)
CH2C12
P-Naphthoic acid
Yield
(3)
(CH2Cl)z
the nitrile by water produced in the hydrogenation reaction
and adsorbed on the catalyst cannot occur, because within 30
minutes the labelled water which was added must equilibrate
with the water on the catalyst to some extent. Moreover ( 3 )
is not hydrolysed in the pre\ence ofwater under the conditions
of the hydrogenation.
Hence the amide oxygen 'itom in (2) does not come from
the water formed during hydrogenation, but apparently arises
by attack of an oxygen atom of the nitro group in ( I ) .
Received, January ZSth, 1963
22
36
Ester
22
35
Diester
62-63
81
84
3
Ester [3]
63 --63,5
92
84
46
Ether
64
37
Ether
43-44
87
93
--- -
--- -
[ I ] H. Rupe and H . Vogler, Helv. chim. Acta 8, 832 (1925).
[2] The natural 1 8 0 content is subtracted from the analytical
figures. Analytical methods according to H . Dahn, H . Moll, and
R . Menasse, Helv. chim. Acta 42, 1225 (1959).
Esterification of Carboxylic Acids with
Aminoacetals
--- 1,3,5-Trichlorophenol
22
Experiments using these amide-acetals and the hitherto
unknown thioacetals of dimethylformamide for the preparation of phosphate esters are in progress.
Received, February 4th, 1963
[Z 441/271 IE]
By H. Brechbuhler, H . Buchi, E. Hatz, Dr. J. Schreiber, and
Prof. Dr. A. Eschenmoser
Organisch-chemisches 1,aboratorium der Eidgenijssischen
Technischen Hochschule, Zurich (Switzerland)
[Z 443/272 IE]
[ * ] I wish to thank Professor C. Djerassi for his generous support,
and Professor W. S. Johnson for his kind interest. Furthermore,
thanks are due to Professor A . Eschenmoser for the exchange of
information.
[ l ] Communication No. 2 on "The Reactions of Amide Acetals".
Communication No. 1: H . Vorbriiggen, Steroids 1 , 45 (1963).
[2] H . Meerwein, W. Florian, N . Schon, and G. Stopp, Liebigs
Ann. Chem. 641, l(1961).
[3] This compound was hitherto unknown and has been characterized by analysis and infrared spectrum.
Hydrogenation of o-Nitrobenzonitrile
to Anthranilamide
By Dr. H. Moll, Prof. Dr. H. Musso
and cand. chem. H. Schroder
Laboratorium fur Organische Chemie der Universitiit
Lausanne (Switzerland) und Chemisches Institut
der Universitat Marburg/Lahn (Germany)
o-Nitrobenzonitrile (1) takes up 3 moles of hydrogen in
30 minutes when it is hydrogenated over palladium or
platinum in methanol, o-aminobenzamide (2) being formed
in 90 % yield [I]. If (1) is hydrogenated in the presence of
heavy water (14.1 % 1 8 0 ) [2], no 1 8 0 is incorporated into (2)
(0.00 % 1 8 0 ) ; when (2) is subjected to the same hydrogenation
conditions, it is again recovered unlabelled (0.05 % 1 8 0 ) .
I n connection with studics in the peptide series, we have
established that dialkylacetals of N,N-dimethylformamide [I]
represent preparatively valuable reagents for esterifying
carboxylic acids [2].
Benzoic acid (0.4 M) reacts [2] with two equivalents of the
diethylacetal of N , N dimethylformamide to give ethyl
benzoate under the following conditions : in methylene
chloride for 5 hr at 40°C; in benzene for 1 hr at 80°C; in
acetonitrile for 36 hr at room temperature. In all cases the
yields are greater than 90 [3].
Esterification of benzoic acid with the acetal made from
dimethylformamide and (+)-S-butan-2-01 proceeds with
almost complete inversion, either in benzene at 80°C or in
acetonitrile at room temperature. This confirms the view
that the reaction involvcs alkylation of the carboxylate
oxygen. In accordance with the S~2-CharaCterof the reaction, benzoic acid cannot be esterified by the acetal made
from N,N-dimethylformamide and neopentql alcohol. In
addition, reaction of thc diethylacetal of N,N-dimethylformamidewith 2,4,6-trimcthylbenzoic acid, which is sterically
hinderedfor A~,2-eSterifiCdtion, yielded the ethyl ester almost
as rapidly as with benzoic acid.
Table 1. Esterification of amino acids and dipeplide derivatives ( I ) with acetals formed
from dimethylformamide and henzyl or p-dodecyl benzyl alcohol [(4) and (5) respectively]
1 1
Acetal
[equiv.]
Solvent,
Ternp.,Time [hr]
N-DOBC-Gly-L-Leu I0.0161
N-DOBC-L-Phe [0.067]
N(a)-DOBC-L-Try 10.0561
N-DOBC-L-Phe-r-Ala[0.051]
(41 t1.61
( 5) 11.31
( 5 ) 11.31
( 5 ) L1.31
Beniene, 80 "C, 1.5
Beuiene, 80 "C, 1.5
Beniene, S O T , 1
CH?C12, 2 0 " C , 18
CH>CIz,20°C, 50
CH .Clz 20 OC, 120
[a] DOBC = CH, -(CH& -0
-CHz-O
-/
\: /
-CO
-.
1
63
90
57
93
109
109
0"
+ 12.0
-6.2'
+5.2"
+6.2'
+2.4'
97
78
73
84
Preparation of these
derivatives: H. Peter, H. Blichi, and L. Loefflrr, unpublished.
[h] Crystalline, analytically pure material shown to he homogeneous by thin-layer
chromatography.
212
Angew. Chem. internat. Edit.
I Vol. 2 (1963) I No. 4
Our findings regarding the esterification of amino acids and
dipeptide derivatives by acetals formed from N,N-dimethylformamide and either benzyl or p-dodecylbenzyl alcohol
[ ( 4 ) and (S), respectively] are reproduced in Table 1. The
benzyl ester of L-valine hydrochloride was isolated in 83 %
yield after removal of the N-protecting group from the b e n q l
ester of N-DOBC-L-valine with trifluoroacetic acid [4], and
corresponds in melting point (138OC) and in specific
rotation (+9.7" in pyridine) with data reported in the
literature [5].
The acetals of N,N-dimethylformamide were obtained
from N,N-dimethylformamide by transacetalization [I]
using the diethjl- [I] or diniethylacetal [6]. This method
failed in the case of p-nitrobenzyl alcohol.
hexano[b]-2-oxa~olidone[ 6 ]is obtained on pyrolysisofmethyltrans-2-iodo-cyclohexane carbamate. Alkyl iodides have been
isolated as by-products in almost quantitative yield in these
reactions. Hydrolysis of the 2-oxazolidones leads to cis+
amino-alcohols. For example Cholcstano [3P, 2P-b]-2-oxazolidone was hydrolysed by methanolic potassium hydroxide to
give a 93 "/, yield of 2P-aminocholestan-3~-ol,m.p. 166 OC;
N,O-diacetyl derivative, m.p. 194 "c'.
The P-iodo-urethanes (2) can be hydrolysed with base to give
the corresponding ethylene-imines ; the imine ring can then
be opened with acid to give trans-p-amino-alcohols [I]. These
reactions make available a stereospecific route to cis- as well
as to trans-P-aminoalcohols from olefins.
Received, February 5th, 1963
[Z 452/273 IE]
IZ 450/283 IE]
Received, February 4th, 1963
[ I ] H. Meerwein, W. Florian, N . Schb'n, and G. Stopp, Liebigs
Ann. Chem. 641, l(1961).
[2] W. Huusermann, diploma thesis, Eidgenossische Technische
Hochschule, Zurich (Switzerland), 1962.
[3] Estimated by recovery of unesterified benzoic acid.
[4] F. Weygund and K . Hunger, Chem. Ber. 95, 1 (1962).
[ S ] J. Shields, W. H. McGregor, and F. Carpenter, J. org. Chemistry 26, 1491 (1961).
[6] H . Bredererk, F. Effenberger, and G. Simchen, Angew. Chem.
73, 493 (1961).
[I] Communication No. 2 on "The Chemistry of Urethanes".
Communication No. 1: A . Hassner and C. Heathcock, Tetrahedron Letters, in the press.
121 National Science Foundation Prcdoctoral Fellow.
[3] Financial assistance by the U. S. National Jnstitutes of
Health, Grant CY-4474 is gratefully acknowledged.
[4] L. Birclcenbach and M . Lindhard, Ber. dtsch. chem. Ges. 64,
1076 (1931); G. Drefahland K . Ponsold, Chern. Ber. 93,519(1960).
[ 5 ] R . Wiltekind, J . Rosenau, and G. Poos, J. org. Chemistry 26,
444 (1951).
[6] M. Mousseron et al., Bull. SOC.chim. France 1953, 737.
[7] M. S. Newman and A . Kulner, J. Amer. chem. SOC.73, 4199
(19.51).
Formation of 2-Oxazolidones from p-Iodourethanes
A Stereospecific Synthesis of cis-3-Amino-Alcohols [ 11
By Dr. C. Heathcock [2] and Prof. Dr. A. Hassner [3]
Acylation of Enamines with Lactimsulfonic
Ester8 111
By Prof. Dr. S. Hunig, Dr. W. Luclte, Dr. V. Meuer [2], and
cdnd. chem. W. Grassmann
Department of Chemistry, University of Colorado,
Boulder, Colorado (U.S.A.)
Chemisches lnstitut der Universitiit Wurzburg (Germany)
Iodine isocyanate adds to olefins to yield P-iodo-isocyanates
which react with alcohols to give P-iodo-urethanes [1,4].
When the olefin used is cyclic, a trans-adduct (2) is obtained
[1,5], which can be converted into a 2-oxazolidone (3).
The smooth acylation of enamines with carbonyl chlorides
[3] can also be applied to iminosulfonic esters, which are
formed for example on Beckmann rearrangement of cyclic
ketoximes ( I ) and which condense with enamines to give (4).
I I1
-C-N
I
F=o
-c-0
I
The results obtained so far are given in Table 1. The 2-oxazolidones were produced by pyrolysis of the corresponding
P-iodo-urethanes, either by heating alone at 100-190 'C, or
in a refluxing solvent. That the reaction involves inversion at
the carbon bearing iodine is shown by the fact that cis-cycloTable I . 2-Oxazolidoncs prepared so far
Olefin
2-Cholestene
1,2-Dihydronaphthalene
Indene
Styrene
Cyclohexene
I
2-Oxazolidone
Cholestano[3f3, 2f3-b]cis-Tetralino[2,1-b]cis-Indano[2,1-b]4-Phenylcis-Cyclohexano[b]-
53
35
61
81
41
227
141
160
136 [7]
55 t61
Compound ( 4 ) is isolatable and is split by dilute acid to give
the equally stable iminoketone ( 5 ) [4], which, when the ring
sizes are suitable, are split by alkali or strong acids into w amino-keto-acids (6). Long chain co-aminocarboxylic acids
are obtained finally by reduction (examples, see Table 1).
Angew. Chem. internat. Edit. 1 Vol. 2 (1963) / No. 4
213
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