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BaSi2 a Phase with Discrete Si4 tetrahedra.

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It is possible to conduct all operations under such mild
conditions, in particular by working at sufficiently low
temperatures, that the configuration of the H 2 N - C ( R ) H group remains unchanged [1151, just as in the similar
synthesis of the aminopyruvaldehyde derivatives (101)
+ (105) + (106) [I151 (see also Section II.3a); no
racemization or Walden inversion occurs. a-Hydroxy-oaminocarboxylic acids (107) are also accessible in this
way from (104), (105), or (106).
By condensing the a-keto-6-aminovaleric acid obtained
in this manner with o-aminobenzaldehyde, Machokin
[ 1 161 was able to synthetize deoxyvasicine, in analogy
to the synthesis developed by Schiipf [I 171 starting from
y-aminobutyraldehyde and o-aminobenzaldehyde.
In the first communication of this series [118], additional
preparative applications proceeding by way of a[115] K . BalenoviC, D . Cerar, and N. Bregant, Croatica Chemica
Acta 28, 279 (1956); Chem. Abstr. 1957, 12000e.
[116] L. Macholan, Chem. Listy wazek 51, 2122 (1957).
[117] C . Schopf’and F. Oechsler, Liebigs Ann. Chem. 523, 1
(1936).
[I181 F. Krohnke, Angew. Chem. 65, 615 (1953).
cyanoanils were discussed. In conjunction with the
Arndt-Eistert reaction, 3,4,5-trimethoxyphenylglyoxylic
acid (109) can be synthetized, for example [I 191.
The intermediate 3,4,5-trimethoxy-w-chloroacetophenone is formed in 40 ”/, yield by the Arndt-Eistert
method. From this, the final product is obtained in 66 ”/,
yield; the overall yield thus amounts to 26.4
z.
IV. Erratum
In Communication No. 11, Angew. Chem. internat. Edit. I ,
626 (1962), page 630, left-hand column, line 16, read: 3-(benzylideneacety1)pyridine.
Cordial thanks are due to Frau Lotte Giirich for her
valuable aid in the composition of the manuscripts of the
second, third, and fourth communications.
Received March 13th. 1962; extended version received
[A 286/97 IE]
January 31st, 1963
German version: Angew. Chem. 75, 317 (1963).
[I191 J. Michalks9 and L. Sadilek, Mh. Chem. 90, 171 (1959);
see also J. Michalskj. and M . Smrr. ibid. 91,307 (1960).
COMMUNICATIONS
Olefins prepared from alkylene phosphoranes and Schiff bases
Reaction of Alkylenetriphenylphosphoraneswith
Schiff Bases
By Priv. Doz. Dr. H. J . Bestmann and Dipl.-Chem. F. Seng
C6HS
stilbene
Institut fur Organische Chemie der Technischen Hochschule
Miinchen (Germany)
Alkylenetriphenylphosphoranes (1) containing a CH2 group
in the P-position to the phosphorus atom react at 130 to
I50 “C with benzylideneaniline (2) as follows:
R-CH ~-CH=P(C~HS)J4- C ~ H S - C H = N - C ~ H ~
BaSi2, a Phase with Discrete Si, Tetrahedra
(2)
(1)
+ R-CH=C=HC-C6Hs
+ P(C5H5)3 + HzN-CaH5
(3)
a) R= H
Received, January 17th, 1963
[ Z 484/323 IE]
Publication withheld until now at the request of the authors.
German version: Angew. Chem. 75, 475 (1963).
By Dr. Herbert Schafer. cand. chern. K. H . Janzon, and
Prof. Dr. Armin Weiss
(5)
(4)
Anorganisch-chernisches lnstitut
der Universitat Heidelberg (Germany)
b) R = C3H7
Ethylenetriphenylphosphorane ( I a) and (2) gave phenylallene (3u) in 62 % yield and triphenylphosphine (4) in 60 %
yield accompanied by aniline (5) in 56 % yield. In an analogous manner, butylenetriphenylphosphorane ( I b) gives 1 phenyl-3-propylallene (3 b) in 46 % yield which, according to
its infrared spectrum, is contaminated by the isomeric acetylene derivative.
Alkylenephosphoranes with no CH2 group in the (3-position
to the phosphorus atom (6) react at 15O-18O0C with Schiff
bases (7) analogous to a Wittig reaction to give olefins (8)
and phenyliminotriphenylphosphorane (9) :
BaSi2, which was first prepared by Wohfer and Schu#”l]
from BaSi and Si, is obtained i n the form of analytically pure
rhombic-dipyramidal single crystals when stoichiometric
proportions of Ba and Si are mclted at 1150 “C in a n inertgas atmosphere and then cooled slowly (Ba found 70.4 %,
calc. 70.9 %; Si found 28.0 %, calc. 29.1 %).
In contrast to SrSi [2] and BaSi [3], which are isotypic with
CaSi [4], the Si atoms in BaSi2 do not form layers as in CaSi2
[5], but form discrete Si4 tetrahedra. The Si-Si distances
within each tetrahedron are 2.34 A, 2.37 A, 2.37 A, 2.41 A,
Si
R-CH=P(C6H5)3
2.48 A, and 2.48 A. The \s< \si/ bond angles are between 57
+ R-CH=N-CtiH5
(61
and 62O. The distances within a tetrahedron are of the same
(71
-+
R-CH=HC-R
+ C~HS-N=P(C~HS)~
magnitude as those in elemental Si (2.34 A), in the \s<si\s(
(9)
chains of CaSi (2.47 A), SrSi (2.52 A), BaSi (2.52 A), or in the
Angew. Chem. internat. Edit. / Vol. 2 (1963) No. 7
393
(8)
layers of CaSiz (2.48 A). A homopolar bond is therefore
indicated. The shortest Ba-Si distance is 3.39 A,the Ba-Ba
distances are 4.38 A and 4.44 A. The shortest Si-Si distance
between tetrahedra is 4.03 A - substantially longer than the
distances within the tetrahedron.
If BaSi2 were largely ionogenic with Ba2+ and Si- ions, then
it would be plausible for the Si- ions to form tetrahedra, just
like phosphorus with which they are isoelectronic.
In contrast to Ba2Si and BaSi, BaSi2 is relatively stable
towards air. It decomposes rapidly in acids; no spontaneously inflammable silanes are formed, however.
Crystallographic data For BaSi2:
orthorhombic
~
a
=
the water-soluble N-free adjuvants (acetone, dioxan), the
rate of reaction is also considerably raised by addition of
water. The bis-perchloroallene (-7) - also referred to as
8-C&lg
(m.p. 93OC from ethanol) obtained in almost
quantitative yield rearranges quantitatively to the E-c6cls
(4), m. p. 44 "C, o n heating for 30 min. at 230 OC.
~
Received, April Sth, 1963
[Z 485/322 IE]
German version: Angew. Chem. 75, 451 (1963).
[I] H . J . Prins, J . prakt. Chcm. (2) 8Y, 421 (1914).
[2] A. Roedig and F. Bischo//; Naturwissenschaften 49,448 (1962).
[3] A. Roedig and P. Buvne~nann, Liebigs Ann. Chem. 600, 10
(1956).
8.92 A, b = 6.80 A, c = 11.58 A
16
deXp, = 3.54 g/cm3, dx = 3.68 g/cm'; space group DTn-Pnma
4 Ba in 4c with x = 0.014, y = 0.250, z = 0.694
4 Ba in 4c with x
=
0.839, y
4 Si in 4c with x
=
0.424, y
=
0.250, z =
0.095
0.250. z = 0.091
Reaction of Enamines
with P-Chlorovinyl Ketones 111
By Dr. W. Schroth and Dipl.-Chem. Gerhard Fischer
4 Si in 4c with x = 0.205, y = 0,250, z -= 0.969
8 Si in 8d with x
= 0.190,
lnstitut fur Organisciie Chemie der Universitlt Leipzig
(Germany)
y = 0,078, z = 0.147
Received, April Sth, 1963
[Z 483/313 IE]
German version: Angew. Chem. 75, 451 (1963).
[I] L. W6hler and W. Schuff; Z. anorg. allg. Chem. 209,33 (1932).
12) G. Rocktuschel and A . Weiss, Z. anorg. allg. Chem. 316, 231
(1962).
[31 G. RockruscheI, Ph. D. Thesis, Technische Hochxhule Darmstadt, 1962.
[4] E. HeIIner, Z . anorg. allg. Chem. 261, 226 (1950).
[ 5 ] J . Bohm and 0 . Hassel, Z. anorg. allg. Chem. 160, 152 (1927).
Enamines react with p-chlorovinylketones to give colored,
occasionally crystalline compounds of type ( I ) . The absence
of the C = O band in the usual carbonyl region indicates mesomerism between the limiting structures a and b.
\ /
\ /
A New Synthesis of Bis-perchloroallene
By Dr. G . MaaB
Chemische Werke Hiils AG.,
Marl/Kreis Recklinghausen (Germany)
Bis-perchloroallene ( I ,2-bis-dichloromethylene tetrachlorocyclobutane) (3) can be prepared by dehydrochlorination of
pentachloropropene with KOH in boiling toluene [l] or with
NaNH2 in liquid NH3 [2]. It is also obtained in small yields
by alkali degradation of ethyl perchlorocrotonate or ethyl
perchlorovinylacetate [3]. Perchlorocrotonyl chloride ( I ) or
perchlorovinylacetyl choride (2) yields exclusively bisperchloroallene in the presence of strong tertiary bases (e.g.
trimethylamine) or solid Na2CO3.
0
2
0
II
II
c1,c-cc1=cc1-c-c1
e 2 c1,c:=cc1-cc1pc-c1
(2)
(1)
These compounds can be protonated and acylated reversibly.
The pyrylium perchlorate (2) is found with perchloric acid.
and those of (2)
The yields of ( I ) lie betwecn 75 and 95
between 50 and 60 %,.
Enamines derived from ddehydes give 2,5-disubstituted
pyrylium salts, e . g . N-dicthylamino-l-butene reacts with
phenyl P-chlorovinyl ketonc to give 5-ethyl-2-phenylpyrylium
perchlorate, m. p. 152- 153 "C.
Enamines derived from cyclic ketones lead to bicyclic pyrylium salts, e . g . I-piperidinocyclopenteneleads via ( I ) [Rl-Rz
= -(CH2)3-,
R3 = CsHs, red needles, m.p. 112-1 13 "C] to
the corresponding pyrylium salt (2), m.p. 161-162OC; 1piperidinocyclohexene leads to (2) [RI-RZ
-(CH2)4-,
R3 = C6H5, m.p. 177---178 "C]; and I-piperidinocycloheptene
leads to (2) [R1-R2 = (<'H2)5 -, R3 = C6H5, m.p. 146 to
147 " C ] .
x,
-
~
2 NalCOl
4 NaCl
+
cx2c:= C--C~'l,
4 CO, i
I
/
cI,c:=c-cc1,
(41
Organic compounds i n the presence of which the reaction
takes place, are (in order of diminishing activity) e . g . dimethylformaniide, dimethylacetamide, formamide, acetamide, acetone, furfural, ethyl acetoacetate, ethyl acetate,
tetrahydrofuran, dioxan. The reaction with NazCO3 in the
presence of the first members of the series is strongly exothermic. It can be moderated by inert solvents (ether, hydrocarbons). Heat strongly accelerates the reaction in the
presence of the last members of the foregoing series. With
394
Whereas the compound ( I ) [R3 = C6H5, red needles, m.p.
148 "C] obtained from I-pyrrolidinoindene resists conversion
into the corresponding pyrylium perchlorate, that [ ( I ) , R3 =
C6H5, orange-red needles, m. p. 133--134 "Cl from 2-piperidinoindene is readily converted into the indeno[l,2-b]pyryliumsalt (3) [R = C6H5, m.p. 215 "C] and to the indeno[1,2-6]pyran (4) [R = C6H5, dark brown platelets, m.p. 197-198 "C].
Angew. Chem. internut. Edit.1 Vof.2 (1963) I No. 7
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