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N N-Dimethyl-4-pyridinamine a Very Effective Acylation Catalyst.

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further stirring and filtration most of the solvent is removed
in a vacuum. The bluish-black leaflets precipitated are
washed with a little cold chloroform and dried in a vacuum.
After dissolution in, and recovery from, chloroform the
yield is 51 % (310mg). (2b) (66%, 460mg) is obtained
analogously from ( l b ) (1 mmole, 490 mg); and (Zc) (364 mg,
1 mmole) affords (4) (260 mg, 59 %), a yellow powder, on
dissolution of the crude product in carbon disulfide, concentration, and rubbing of the residue with methanol.
Compound
x-
i
4.00
828
827
824
4.01
4.63
2010
1910
1890
1870
3.69
1950
1900
3.63
3.56
825
747
700
692
746
698
690
( 3 ) r6.71.
IfH
(21
863
818
87 5
810
750
697
760
694
Received: September 26, 1969
[Z 99 IE]
German version: Angew. Chem. 81, 1000 (1969)
[*] Dr. H. Kopf and K. H. Rathlein
Institut fur Anorganische Chemie der Universitat
87 Wurzburg, Rontgenring 11 (Germany)
[l] H. Schumann, 0. Stelzer, and W. Gick, Angew. Chem. 81,
256 (1969); Angew. Chem. internat. Edit. 8, 271 (1969).
[2] H. Kopf and M . Schmidt, 2. anorg. allg. Chem. 340, 139
(1965).
[3] H. Kopf, B. Block, and M . Schmidt, Z . Naturforsch. 226,
1077 (1967).
[41 Quartz lamp Q 81, Hanau.
[5] W. Strohmeier and G . Schonauer, Chem. Ber. 94,1346 (1961).
[6] For the influence of ligands L in (C5H&TiL2 on T C ~ H see
S
H. C . Beachell and S . A . Butter, Inorg. Chem. 4,1133 (1965), and
B. Block, Dissertation, Universitat Wiirzburg (Germany), 1968.
[7] Cf. H. Kopf, 2. Naturforsch. 23b, 1531 (1968). If the Ti
in (2) is replaced by Mo, the mesomerism is blocked by
the already occupied $0-orbital on MoIv. Correspondingly,
( C S H ~ ) ~ M O ( S Cand
~ H ~Mo(CO)6
)~
give the trisubstituted carbony1 ( C ~ H ~ ) ~ M O ( S C ~ H ~ ) ~ MinO which,
( C O ) ~by
, a reversal, the
cyclopentadienylmetal acts as donor to the carbonylmetal 181.
IS] C. H . Campbeit, A . R. Dias, and M . L . H . Green, Progr.
organometallic Chem., Proc. Fourth Int. Conf. Organometallic
Chem., Bristol 1969, contribution 56.
191 K . Andru, J . organometallic Chem. 11, 567 (1968).
N,N-Dimethyl-.l-pyridinamine,a Very Effective
Acylation Catalyst
By W. Steglich and G. Hofle[*l
We have found that N,N-dimethyl-4-pyridinamine( I ) [I],
alone or mixed with triethylamine, is a superlative acylation
catalyst, much superior to pyridine121.
N
C-Acylations: The Dakin-West reaction 151 was chosen as
example, its most important step being the pyridine-catalyzed
acylation of the 5-oxazolone (2) to the 4-acyl-5-oxazolone
735
694
740
690
[a] Singlet, measured for saturated solutions in CSz with TMS as
external standard. Ibl CsH5 group. tcl C ~ H group.
S
H3C,
0-Acylations: Acylation of tertiary alcohols is considered to
be difficult 131. For example, tert-butyl alcohol and l-methylI-cyclohexanol are not acylated by acetic anhydride and
pyridine [41. Yet acetylation in the presence of an equivalent
amount of ( I ) is complete after 10 hours at room temperature ( N M R kinetics). For preparative purposes it suffices to
add catalytic amounts of ( I ) and to bind the acid formed by
triethylamine. [Example: I-Methyl-1-cyclohexanol (1 1.4 g,
0.1 mole), acetic anhydride (20 ml, 0.21 mole), triethylamine
(20 ml, 0.15 mole), and ( I ) (0.5 g, 4.1 mmoles); after 14
hours at room temperature 86% of acetate; analogously,
60% of fert-butyl acetate. The amounts of acetate formed by
pyridine and/or triethylamine are less than 5 %.I
,CH3
Angew. Chem. internat. Edit. J Vol. 8 (1969) J No. I 2
(3)
COR2
(4)
(a), R' = R3 = CH,, R2 = CsH5
(b), R' = C6H5, R2 = R3 = CH3
Here (1) accelerates this reaction much more than pyridine
does. For example, acetylation of (2a) to (3a) with pyridine
requires about 6 hoursc71, but with 0.05 part of (1) only
3 minutes are needed. At the same time the decarboxylative
ring fission is greatly accelerated, so that the Dakin-West
reaction can be carried out at room temperature.
Analogously to (4a) (see below), 2-phenylglycine afforded
N-(1-phenylacetony1)acetamide (4b) in good yield after 13
hours' stirring. Further, conversion of oxazolones into ( 4 ) by
carboxylic acids [7,81 is effected smoothly a t room temperature under catalysis by ( I ) ; for example, (2a) (0.97 g, 5.55
mmoles), glacial acetic acid (0.32 ml, 5.55 mmoles), and ( I )
(40 mg, 0.33 mmole) in methylene chloride give 73 % (0.80 g)
of (4a) after one day.
N-(1-Methylacefonyljbenzamide(4a)
N-Benzoylalanine (3.9 g, 20 mmoles) and ( I ) (0.1 g, 0.82
mmole) are stirred with acetic anhydride (4 ml, 42 mmoles)
and triethylamine (4ml, 0.29 mmole). Lively evolution of
COz and slight warming occur. After 30 min glacial acetic
acid (30ml) is added, then the solution is set aside for 30
min, concentrated in a vacuum, shaken with 2 N NaOH, and
extracted with ether. Shaking the ethereal phase with 1 NHCl, drying, and evaporation gives 78% (3.0 g) of (4a), m.p.
63 "C (m.p. in [91 is 69 "C).
Received: August 28, 1969
[Z 100 IE]
German version: Angew. Chern. 81, 1001 (1969)
[*I Doz. Dr. W. Steglich and Dr. G. Hofle
Organisch-Chemisches Institut der Technischen Hochschule
8 Miinchen 2, Arcisstrasse 21 (Germany)
[l] L. Pentimalli, Gazz. chim. ital. 94, 902 (1964).
121 For further uses of ( I ) as catalyst see G. Hifie and W. StegIich, Tetrahedron Letters, in press.
131 Cf. e.g. H. A . Staab, Angew. Chem. 74, 407 (1962); Angew.
Chem. internat. Edit. I , 351 (1962).
[4] L. F. Fieser and M . Fieser: Organische Chemie. Verlag Chemie, Weinheim 1965, p. 339
[5] H. D . Dakin and R. West, J. biol. Chemistry 78, 91 (1928).
[6] Y. Iwakura, F. Toda, and H . Suzuki, J. org. Chemistry 32,
440 (1967).
[7] W. Steglich and G . Hoye, Tetrahedron Letters 1968, 1619.
[8] J. A. King and F . H . McMillan, J. Amer. chem. SOC.77,2814
(1955).
191.'II Steglich and G . Hoife, Chem. Ber. 102, 883 (1969).
98 1
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