close

Вход

Забыли?

вход по аккаунту

?

Cyclic Methylenephosphoranes.

код для вставкиСкачать
With SiC14, the crystalline spiro-compound (10) (decomposes above 200 "C)is formed.
Cyclic Methylenephosphoranes [11
By Dr. G.Mbkl
Chemisches Institut der UniversiUt Wiirzburg (Germany)
The compounds GjHsSiCI3 and (C6H&SiCI2 fail to react
under the conditions applied in the above synthesis.
Received, January 2nd. 1963 [2420/245 IB]
Cyclic phosphonium salts (3) required for the synthesis of
six-membered rings containing an unsaturated methylene
phosphorane group (61 were prcpared a) by direct intramolecular quatemization 121 during cleavage of the ether ( I )
(mp. 43-44"C) with a mixture of hydrobromic and glacial
acetic acids to give (3), where K=H and X-BF4e. m.p.
193-195"C, in 74% yield; or b) by intramolecular Calkylation [l ,31 of the intermediate methylenephosphorane
(3) where R
c6H5 and X = BF4e, m.p. 248-250°C,
obtained in 68 % yield from (21 where R = C a 5 and X = Br,
m.p. 225-227°C. The cyclic quaternary salts (3) can be
smoothly converted into bromindkd phosphonium salts (4).
where. R = H and X = BF4e, m.p. 192"C, 91 % yield or
R = GH5 and X = BF4Q, m.p. 195-197"C. 86% yield,
using N-bromosuccinimide in boiling chloroform. Yellow
(R = H) or orange-red (R = C&) solutions ofthe methylenephosphoranes (6) are obtained by treating (4) with sodamide
in liquid ammonia and toluene or with potassium t-butoxide
in dimethylformamide, which results in simultaneous dehydrobromination.
Salts (S), where X = CI, are formed by treatment of these
solutions with gaseous hydrogen chloride; other salts (5)
have R = H, X = B(C&I5)48 and m.p. 220-221OC; or
R
X BF40 and m.p. 178 -180°C.
-
Base-CatalysedFragmentationsof Azo Compounds,
a Route to the o-Bromophenyl Anion
By Dr. R.W. Hoffmann
Jnstitut ft Organische Chemie
der Universiat Heidelberg (Germany)
The o-bromophenyl anion ( I ) occurs as an intermediate
stage in the equilibrium system [11
- w5,-
In order to investigate the nature of (I) with regard to the
formation of bromobenzene (2) and dehydrobenzene (benzyne) (3), it is desirable to generate (1) independent of (2)
and (3) and under conditions which do not permit reformation of (1) from (2) and (3). This was achieved by
an ethoxide catalysed fragmentation of compounds of type (4)
in ethanol.
Treatment of (4a) at 4C C and of (4b) at 20 "C eac- with half
an equivalent of sodium ethoxide solution led to vigorous
evolution of nitrogen and liberation of 7 % ionic bromine. Using gas chromatography, 75-85 % bromobenzene
and 2-3% phenetole were detected amongst the products, in addition to 58 % diethyl carbonate and 92% ethyl
benzoate, respectively. It is clear that the phenetole obtained
can be formed only by addition of ethanol onto dehydrobenzene, because fragmentation of (412)and (4d) yield 3-and
4-ethoxytoluene in the same ratio of 3:2 [2].
The ratio of the yield of bromobenzene to that of phenetole
(w 30:l) and to that of bromide ion (w 1O:l) gives an
upper and lower limit, respectively, for the preponderance of
protonisation of (I) over the loss of bromide ion from ( I )
[3]. Proton transfer to a phenyl anion is extremely rapid,
hence the loss of bromide ion, although about 10-30 times
slower, must also occur very rapidly. This is in accordance
with other findings [3,4].
[Z 4251256 IB1
Received, January 2nd. 1963
[l]G. Witfigand R. W. Hoffmann, Chem. Ber. 95,2729 (1962).
[2]This isomer ratio is in agreement with that obtained by G.
Wittig and G. Yargas for the addition of ethanol onto 3,edehydrotoluene (unpublished mults).
[3]Cf. J. D. Roberts et al., J. Amer. chcm. Soc.78, 601 (1956).
[4] H.Gilman and R. D. Gorsich, J. Amer. chem. Soc. 78,2217
(1956); 79,2625 (1957).
Angew. Chem. internut. Edit. I Vol. 2 (1963) I No. 3
I /
11. -111.
I
B
A direct conversion of (4) into (5) does not occur, since (4)
forms (6) even with 2 N NaOH in aqueous solution. The
methylenephosphoranes (6) are precipitated from water as
amorphous powdm (R = H, yellow, X m a = 362, 420 mp
(benzene); R = GjH5, orange-red, Amax 387,426, 488mp).
In contrast to its unusual stabilily towards hydrolysis cleavage to give (71,where R H.m.p. 140-142"C, occurs
only in hot water - (6) is very sensitive to oxygen. In methanol (alkoxide method) in the prcsence of air, (6), where
R = H,forms several stable red- to violet-colored methylenephosphoranes within a short time; these can be separated by
chromatography.
On consideration of other comparable methylenephosphoranes (lo), where R = H or C'6H5, the ready formation
of (6) and its stability can only he explained by a gain in
resonance energy resulting from the attainment in the heterocyclic ring of cyclic conjugation involving the pZ-dZ double
bond of the ylene. In accordance with the small participation
of the ylide mesomeric form in (6), formation of betaines
with benzaldehyde or p-nitrobenmldehyde and hence formation of olefins therefrom does not occur, even under drastic
-
-
153
-
conditions, although the dihydro compound (8) reacts
smoothly with benzaldehyde to give (91,where R H,as an
oil. The methylenephosphoranes (6)couple readily with diazonium salts [4]to give blue mono- and bisazo-compounds.
Received. January 2nd, 1963
IZ4271260 IE]
[I] Second communication.- First communication:G. MGrkl, Z.
Naturfomh., in the press.
[21 Cf. F. G. Mann. J. chem. Soc. (London) 1951,411.
[3] H.I. Bestman, Z . Naturforsch. 176. 78 (1962).
[4] G. M&kl, Tetrahedron Letters 1961,No, 22,807.
Di-(O,N-dialkylformimido) Disulfides
By Priv.-Doz. Dr. W. Walter and DipLChem. K.-D. Bode
Chemisches Staatsinstitut. Institut fur Organische Chemie
der Universitat Hamburg (Germany)
of Zhydroxy-2.6-dialkyl- I ,Bcyclohexanediones [21 was as
signed to them. Detailed investigations have now established
that the last-named compounds are in fact derivatives of ybutyrolactone, e.g. (I),chicfly since Clemmensen reduction
yields an a,y-dialkyl-y-butyrolactone(2).
9
(1)
(2)
Further investigations then showed that the reaction products
with chloramine are not 0-arylhydroxylamines but doubly
unsaturated e-caprolactams of constitution (3). The positions
of the double bonds are confirmed by infrared and proton
magnetic resonance spectra of the compounds (3)-(5) and
by cleavage of (3) and (4) with mineral acids to yield
nitrogen-free keto compounds.
The salts of formamidine disulfides (I) prepared by oxidation
of thiourea are known.
0
R3C:~'
11
H~N-C-S-S-C-NHZIX~~
AH2@
We have now found that N-monosubstituted thiourethans
(2) may be oxidized to give di-(ON-dialkylformimido)
disulfides (4) with hydrogen peroxide. The thiourethan-Soxide (3) occurring as an intermediate in the reaction may
be identified by chromatography and spraying with ferric
chloride.
+ € I 2 0 2 + R-NH-C-OR'
II
(2)
(3)
S
(2)
+ (3) +
-
I
OR'
b
" 3 3 (
LH
Hz
Received. January 7th. 1963
(4)
[Z4311258 IE]
I
The Action of Imidazole in Peptide Syntheses with
Thiophenyl Compounds
-
R = W S
Peptide Syntheses XXW [l]
Besides (40) and (461, the corresponding urethans are formed
by oxidative desulfuriztition. It can be shown that an Soxide also occurs as an intermediate step even with tertiary
thiourethans by the appearance of a red-brown color with
ferric chloride on oxidation of N,N-dimethyl-O-(o-nitroitropheny1)thiourethan. This is due here to a 'labile peroxide'
already postulated by Billetcr [I].
It is remarkable that the disulfides (4) derived from Nsubstituted thiourethans are stable in the free state whereas
only the salts can be prepared with analogous compounds of
thiourethan ( I ) ,
Received, January 14th. 1963
[Z429/257 IB]
[I]0.Billeter, Ber. dtsch. chem. Ges. 43, 1853 [1910].
The Action of chloramine on &SubstitutedPhenols
By Prof. Dr.W.Theilacker, Dr. K.Ebke,
DipLChem. L. Seidl, and DipLChem S. Schwerin
Institut fur organische Chemie
der Technischen Hochschule Hannover (Germany)
By Prof. Dr. Th. Wieland, Dr. H.Determann
and cand. chem. W. Kahle
lnstitut fur Organische Chemie
der Universitat Frankfurt/Main (Germany)
Thiophenyl compounds of acyluted amino acids can serve as
activated derivatives for peptide syntheses [2]. The possibility of using water as solvent seemed particularly advantageous, for it is then also possible to couple even free amino
acids in the presence of weak bases such as pyridine [3].
Nevertheless, even after long heating, the yields only amounted to about 50%. We have now found that good yields of
peptide can be achieved in the presence of imidazole under
much milder conditions and without significant racemization.
Thus, 1.5 g (3.46x 10-3 moles)of the thiophenyl ester of carbobawxyglycyl-bphenylalanine (m.p. 104OC) and 0.42 g (556x10-3 moles) of
glycineina solutiond 10 g d irnidazole in 3 ml of water were maintained
at 40'C for 1 hour. Work-up ULI described in the litefatw [4] afforded
1.2 g (88 % of theory) of an oil of carbobenzoxyglycylphe~~lanylglycine. On applying the Andwon test [S] to its ethyl ester, this was
foundto be the Lcompound to over 95 %.
Received. January 16th, 1963
When phenoxides from 2,6-disubstituted phenols are treated
in fused phenols with chloramine, colorless, stable, beautifully crystalline substances are obtained which are distillable in vacuo [I] and which we have considered as 0arylhydroxylamines, on account of their properties and
rearrangement by mineral acids. The products resulting with
mineral acid do not contain nitrogen but 'contain two
additional oxygen atoms; on account of their properties and
the products of their oxidative degradation, the constitution
154
Ij--NH )3-CII#
I12C,c/
OR'
GHs: m.p. = 98 ' C
(4b) R' = C J H ~ m.p.
:
88-90 OC
(40) R'
ClI
(3)
[I] K. Ebke. Ph.D. thesis, Technische Hochschule Hannover
1959;see also W. Theilacker and E. Wegner, Angew. Chem. 72,
131 (1960).
[2] W.Theilacker, Angew. ('hem. 72,498 (1960).
R-N-C-S-S-C-N-R
(4)
!-l!p, p : r i 3
f'i'
AH2@ (1)
RNH-C-OR'
\
IlC\
[Z432/261 IE1
[I] CommunicationNo. 26: Th. Wielandand K. Vogeler,Angew.
Chem. internat. Edit. 2,42 (1962).
[2] Th. Wiehnd and W. Sch6fer, Angew. Chem. 63, 146 (1951).
[3] Th. Wiehndet al., Liebigs Ann. Chem. 573,99 (1951).
[4] H.Determann, 0.Zipp, and Th. Wieland, Liebig Ann. Chem.
651, 172 (1962).
[S] G. W.Anderson and F. M. Callahan, J. Amer. chem. Soc. 80,
2902 (1958).
Angew. Chem. internut. Edit. / Vol. 2 (1963) / No. 3
Документ
Категория
Без категории
Просмотров
1
Размер файла
215 Кб
Теги
cyclic, methylenephosphoranes
1/--страниц
Пожаловаться на содержимое документа