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Direct Aminolysis of Unactivated Esters at High-Pressure.

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[cm-'1). 1785 (THF); 1780 vs, 1742 vw (sh) (KBr); 'H-NMR (300 MHz,
CDCIX, +28"C): 6 = 1.68, 1.77 (2d, CH,, 2~ 15H; 'J(Rh,H)=O.5-0.6
Hz), 0.46, 0.53, 0.90, 1.05, 1.30 (5m, cyclopropyl-H, 5 x I H), 0.19 (m,
'J(Rh,H)=O.X Hz, I H), 1.52 (m,2H), 2.58 (m,I H), 2.73 (in, I H) (together KhlCIH,). A correct elemental analysis (C, H, 0, Rh) was obtained. MS: m / z 598 (molecular ion for CzsHaoORh2;El and F D spectra).
[5] Review: a) W. A. Herrmann, PureAppl. Chem. 54 (1982) 65; J . Organomet Chem. 250 (1983) 319; Ado. Organomet. Chem. 20 (1982) 159.
[6] More recent examples: a) W. A. Herrmann, C. Weber, M. L. Ziegler, C.
Pdhl, Chem. Ber. 117 (1984) 875, and references cited therein; b) W. A.
Herrmann, C. Bauer, J. Weichmann, J . Organomet. Chem. 243 (1983)
C21: c) W. Kalcher, W. A. Herrmann, Chem. Ber. 118 (1985) 3861, and
references cited therein.
171 CAD-4 (Enrdf-Nonlus), MoKn, graphite monochromator, o-scan
( A U = 1.0"+0.35 tgff, 2 ° 6 f f 5 2 0 0 ) , tm,,=60s, h(-7/7),
I ( - 17/17), 5096 measured reflections, 4069 of which with I > Icr(l);
after averaging, 2146 reflections remained.-Structure solution: Patterson and difference Fourier methods; all atoms with the exception of
hydrogen and all nondisordered carbon atoms were anisotropically refined; ideal positions were assumed for the hydrogen atoms and used in
calculating the structure factors; however, they were not refined.
R =0.040, R , =0.041.
[S] Example: K. M. Motyl, J. R. Norton, C. K. Schauer, 0. P. Anderson, J .
Am. Chem. Sac. 104 (1982) 7325.
[9] C. J. Schaverien, M. Green, A. G . Orpen, I. D. Williams, J. Chem. Sac.
Chem. Commun. 1982, 912.
[I01 a) P. Binger, M. J. Doyle, R. Benn, Chem. Ber. 116 (1983) 1; b) P. Binger,
A. Brinkmann, P. Wedemann, ibid. 116 (1983) 2920.
[ I I] Example: H. M. Biich, P. Binger, R. Benn, C. Kriiger, A. Rufinska, Angew Chem. 95 (1983) 814; Angew. Chem. Int. Ed. Engl. 22 (1983) 774.
Direct Aminolysis of Unactivated Esters at
By Kiyoshi Matsumoto,* Shiro Hashimoto, and
Shinichi Otani
In memoriam Ryozo Goto
The direct conversion of esters into acid amides is
known to be a difficult reaction,"] though it potentially
constitutes a useful synthetic strategy and several methods
designed to facilitate it have been r e p ~ r t e d . [ ~ -Uncata'~
lyzed aminolysis with primary amines requires temperatures in excess of 200"C,'61 while the corresponding reaction with secondary amines has never been reported.
We have now found that even secondary amines 2 react
in high yield at room temperature or 35-45°C with a wide
variety of unactivated esters 1 to give acid amides 3 if the
reactions are carried out under a few kbar (Table l)."l
Neither a n inert atmosphere nor dry solvents are required.
The reaction is extremely clean and therefore the work-up
procedure is straightforward; even the hydrolysis procedure used in the excellent method with alkylaluminum amide reagents is unnecessary. Usually, the solution of the
products 3 contains only the esters 1, if the yield is not
quantitative, and excess amine 2. Naturally, this method is
also applicable to primary amines (see Table 1).
The reaction of 13-butyrolactone 4 at 45°C with an extremely unreactive amine such as diphenylamine['' further
illustrates the utility and mildness of the method. The desired amide 5 is obtained in 28% yield, along with 35% 3(N.N-dipheny1amino)butyric acid 6. Under conventional
conditions at 180-190°C-without use of pressure-only
0.8% of the acid is formed.
[*I Prof. Dr.
K. Matsumoto, S. Hashimoto, Prof. Dr. S. Otani
College of Liberal Arts and Sciences, Kyoto University
Kyoto 606 (Japan)
[*'I This work was supported by the Japanese Ministry of Education
(No. 61840017).
Angew. Chem. Int. Ed. Engl. 25 (1986) No. 6
+ HNR3R4
Table 1. Aminolysis of unactivated esters I to acid amides 3 at 8 kbar with
primary and secondary amines 2 171 [a].
R4 T [ b ] Yield
I"C1 I%l[cl
Me [dl
Et [el
PhC H ( 0 H )
Me [el
118-1 19
[a] Reaction conditions not optimized. [b] Temperatures: 35 +2"C, 45 22°C.
room temperature. [c] Yields of pure isolated amldes 3; all amides gave correct C H N analyses and IR, 'H-NMR, and "C-NMR spectra. [dl When octylamine IS used instead of pyrrolidine at normal pressure, then heating to
230°C IS necessary 161. [el Does not react under vapor-phase chromatography
conditions at 190°C IS].
Because of its broad applicability and the low temperatures, the method presented here appears to be superior to
reactions with alkylaluminum amides.['] Whereas these
reagents often react with such a valuable functional group
as a cyano group,"'] this is not the case in our method. The
high acceleration of the aminolysis of esters by application
of pressure would suggest that the formation of a tetrahedral zwitterion is rate-determining." I ]
Received: February I I. 1986 [Z 1666 IE]
German version: Angew. Chem. 98 (1986) 569
[I] Review: A. L. J. Beckwith in J. Zabicky (Ed.): The Chemistry o/Amrdes.
Interscience, New York 1970, p. 96.
121 Strong alkali metal catalysts: a) NaOCH,: R. J. De Feo, P. D. Strickler,
J . Org. Chem. 28 (1963) 2915; E. L. Allred, M. D. Hurwitz, ibid. 30
(1965) 2376; b) NaNH2 or KNH2: E. S. Stern, Chem. Ind. (London)
1956, 277; C. F. Huebner, R. Lucas, H. B. MacPhillamy, H. A. Troxell,
J . Am. Chem. Sac. 77(1955) 469; c) nBuLi: K. W. Young, J. G . Cannon,
J. G. Rose, Tetrahedron Lett. 1970. 1791; d) NaH: B. Singh, Tetrahedron
Lett. 1971, 321; d) LiAIH,: J. Petit, R. Poisson, C . R . Hebd. Seances
Acad. Sci. 247 (1958) 1628; D. A. Evans, Tetrahedron L e f f 1969. 1573; e)
RMgX: H. L. Bassett, C. R. Thomas, J. Chem. Sac. (London) 1954.
131 Milder catalysts: a) 2-Pyridone: T. Openshaw, N. Whittaker, J . Chem.
Sac. (London) C1969.89; b) BBr,: H. Yazawa, K. Tanaka, K. Kariyone,
Tetrahedron Lett. 1974. 3995.
[41 Metal amide reagents: a) R,SnNMe2: T. A. George, M. F. Lappert, J .
Chem. Sac. (London) A 1969, 992; G. Chandra, T. A. George, M. F. Lappert, ibid. 1969, 2565; b) Me2AINR'R2: A. Basha, M. Lipton, S . M.
Weinreb, Tetrahedron Lett. 1977. 4171.
[5] Unusually facile aminolysis of p-ketoesters: M. Labelle, D. Gravel, J.
Chem. Sac. Chem. Commun. 1985. 105.
161 E. T. Roe, J. T. Scanlan, D. Swern, J. Am. Chem. Sac. 71 (1949) 2215; R.
Crossley, A. C. W. Curran, D. G. Hill, J . Chem. Sac. Perkm Trans. I
1976. 977.
0 VCH Verlagsgesellschaft mbH. 0-6940 Weinheim. 1986
0570-0833/86/0606-0565 !3 02.50/0
[7] Procedure: A mixture of the ester 1 (5 mmol) and the amine 2 (IOmmol)
was diluted with acetonitrile in an 8-mL Teflon capsule, which was then
stored for 3 d at 8 kbar. After evaporation of the solvent and amine, the
residue was dissolved in dichloromethane and extracted with dilute HCI
(saturated with ammonium sulfate in the case of water-soluble amides
3). In the case of incomplete reaction, the amide was readily separated
by flash chromatography.- For reviews on organic syntheses under
high-pressure, including a description of the high-pressure equipment
used in this study, see: K. Matsumoto, A. Sera, T. Uchida, Svnrhesis
1985. I ; K. Matsumoto, A. Sera, ibid. 1985. 999.
[8] Y. Iwakura, K. Nagakubo, J. Aoki, A. Yamada, Nippon Kugaku Zusshi
75 (1954) 315; Cfiem. Ab.rfr.51 (1957) 11246b.
191 M . F. Lipton, A. Basha, S. M. Weinreb, Org. Synth. 59 (1980) 49.
[lo] H. Hoberg, J B. Mur, J . Organornet. Chem. 17 (1969) P30; T. Hirabayashi, K Itoh, S. Sakai, Y. Ishii, ibid. 21 (1970) 273.
[ I I ] For a recent mechanistic study on the aminolysis of esters' I. M. Kovach, M. Belz, M. Larson, S. Rousy, R. L. Schowen, J . Am. Chem. SOC.
107 (1985) 7360.
Red, Transparent Alkali Metal Silicides with Si,
By Hans Georg uon Schnering,* Martin Schwarz, and
Reinhard Nesper
In memoriam Herbert Schafer
The theoretically predicted structure of the fourfold p3coordinated tetralithiotetrahedrane Li,C,[" has not yet
been experimentally confirmed. The homologous silicide is
unknown,l2]and the germanide LiGe does not have Ge, tetrahedrons as anions.131The tetrahedral arrangement, however, has been long established for all higher homologues
of the first and fourth main g r o ~ p s . [ ~We
- ~ ]have therefore
attempted to determine, by the synthesis of ternary and
quaternary silicides M*Si (M* =mixed alkali metal),
whether lithium can at least be partially present as a p3bonded metal atom on Si4 tetrahedra. These experiments
were successful and led, surprisingly, to the first red, transparent metal silicides.
Reaction of an alkali metal mixture, Li M (M = NaCs) with silicon results in the formation of both red, transparent and metallic grey, opaque silicides. It is still unclear
which conditions with respect to M* :Si and Li :M and
which structures are characteristic for either of the two
types. We have established, however, that the light absorption of the red silicides K3LiSi4and K,Li(S,), is an intrinsic property of these compounds. (Preparation: stoichiometric mixture of the elements; sealed Nb ampoule in a
quartz ampoule; 4 h heating at 800°C; 4 h annealing at
800°C; slow cooling over 12 h.) These red silicides are also
flammable in air and form flammable silanes with protic
The structures of the new silicides (Fig. 1) belong to the
types already known or are variants of these. Thus,
K7Li(Si4)2belongs to the Rb7Na(Ge4)2type,"] and K3LiSi4
exhibits the polymeric chain A[M'(Y4)] known for the
Cs2Na,Ge, type.[81 In K3LiSi,, the Si:- tetrahedra are
linked by the Li atoms to form infinite one-dimensional
chains :[Li(Si4)l3 -, thereby functioning twice as pJigands. Li is thus bonded to six Si atoms with d(LiSi) = 258.8-294.7 pm (a=272.9 pm), and, at the same time,
two triangular faces of the Sij- tetrahedron are capped
by Li. In contrast to C S ~ N ~ ~however,
G ~ , , only
~ ~ one
~ other
face is capped by a K atom as pJigand; the other K atoms
bridge only edges or coordinate only corners of the Si, te-
Prof. Dr. H. G. von Schnering, DipLChem. M. Schwarz, Dr. R. Nesper
Max-Planck-lnstitut fur Festkorperforschung
Heisenbergstrasse I , D-7000 Stuttgart 80 (FRG)
0 VCH Verlaqsge.~ellschaJimbH.
0-6940 Weinheim. 1986
Fig. 1. Crystal structures of K3LiSi4 and K,Li(Si& with the bond lengths in
the polymeric chain L[Li(Si4)]3- and in the dumb-bell-shaped structural
group [(Si4)Li(Si4)]'-. In both structures, the additional p3-coordinations by
the K atoms are given on the right margin (hatched lines).-Crystallographic
data: K?LiSi,; Pnmu (No. 62); a=765.1(4), b=980.5(4), f = 1222.1(9) pm;
2 = 4 : 1253 reflections; R(aniso)=0.033.-KK,Li(Si,)l;
Pa3 (No. 205);
u = 124933) pm; Z = 4 ; 495 reflections, R(aniso)=0.026 Further details of
the crystal structure investigation may be obtained from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number C S D 51899, the
names of the authors, and the journal citation.
trahedron (coordination number 6 and 7, respectively, with
K-Si = 339.4-356.9 pm and 354.6-380.7 pm, respectively).
The bond lengths in the anion are on the average z(SiSi) = 242.4 pm (236.3-244.9 pm) and are thus larger than in
NaSi (240.9 pmt9]). The Si, tetrahedra in K7Li(Si4)2,with
the dumb-bell-shaped unit [Li(Si4),17-, are also larger than
in NaSi: 6(Si-Si)=241.8 pm; d(Li-Si)=271.4 pm. In this
structure, six of the K atoms serve as further p3-ligands
(K-Si =338.5-351.2 pm with 6=343.9 pm), whereas one of
the K atoms exhibits no K-Si contacts.
Some of the structural details could be of importance for
theoretical understanding. Thus, in K,Li(Si4)2, the Si-Si
distances in the tetrahedral faces bonded to p3(Li) are
large (244.6pm) and those in the faces bonded to p3(K)
small (238.9 pm). In K3LiSi4, the Si:- tetrahedra are also
distorted. The one edge of the tetrahedron not involved in
a p3(Li) cap structure has the smallest Si-Si distance
(236.3 pm) and the edge involved in two p3(Li) cap structures the largest Si-Si distance (244.9 pm). Apparently, the
strongly covalent Li-Si interaction of the p3-bonded Li
atom weakens the Si-Si bonds of the Si:- tetrahedron.
Even the noted deformations due d o incomplete p,-coordination can no longer permit a doubt as to the favoring of
the Td form for Li,Si, as well.['o1Although Ritchie et al.
predict a higher stability for the DZdform,'"] more detailed
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Angew. Chem. Int. Ed. Engl. 25 (1986) No. 6
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unactivated, aminolysis, esters, high, direct, pressure
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