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Azulenes from Pyrylium Salts and Wittig Reagent.

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(2); n = 1
(3); n = 2
talline stable compounds, produce a very strong EPR-signal.
Compound (2) was obtained from the dipyrylium salt ( 4 ) by
two-fold nitromethane-condensation 131, reduction, diazotization, hydrolysis and dehydrogenation of the bis-phenol. Compound (3) was prepared from 2,4,6-triphenyIphenol with
SOC12 and AIC13, followed by dehydrogenation of the bisphenol, and independently from 2,6-diphenyl-4-(4-bromopheny1)anisoIe and copper powder, followed by cleavage of
the ether, and dehydrogenation.
If the 2,4,6-triphenylpyrylium salt ( I l l ) is allowed to react
with (2) in CHzClz o r in a large quantity of acetonitrile, in
which it is relatively soluble, then two molecules of (la) and
one of (2) condense t o form a decp blue azulene (4), m.p.
289 to 290°C, in about 30 X yield. Its structure follows inter
nlin from its spectrum in the visihle region, its fluorescence,
infrared and NMR spectra and from the fact that (4) gives a
colorless salt with acids which reverts to the blue substance
on addition of sufficient water or with bases. With (16) and
( l c ) , chloro- or bromo-substituted azulenes are formed. The
reaction did not occur with tctraphenyl- and pentaphenylpyrylium salts.
The novel reaction must go through a primary addition
product, such as (3), which then undergoes deprotonation,
ring-opening, aldol condensation between C-4 and C-5', and
a peculiar transannular C -C bonding between C-4' and
the methylene-carbon of (2) with elimination of triphenylphosphine (which we were able to isolate as its adduct with
HgC12, m.p. 285 "C) to form the iizulene.
Received, August Znd, 1963
[Z 557/388 t E
German versioii: Angew. Chem. 75, 860 (1963)
[I] K . Dimroth and K. H . Wow, unpublished experiments; G.
Markl, Angew. Chem. 74, 696 (1962); Angew. Chem. internat.
Edit. I, 511 (1962).
The oxidation power of (3) is greater than that of (2) and of
(I), because (3) is capable of dehydrogenating the phenol of
(2) or of (I) immediately. The new radicals may be compared
with the C-radicals of the type of Tschitschibabin's hydrocarbon. The phenyl substitutens (ortho to the oxygen atom)
enhance the stability. Bis-phenols of type (2) and (3) which
lack these substituents d o not yield stable radicals.
Received, August Znd, 1963
[Z 558/382 IEI
The Diazanorcaradiene Ring System 111
By Dr. Gunther Maier
Instililt fur Organische Chemie
dcr Technischen Hochschule Karlsruhe (Germany)
German version: Angew. Chem. 75, 860 (1963)
[l] J. Plesek, Chem. Listy 50, 246 (1956); H. D. Schminke, Ph.
D. Thesis, Universitht Marburg, 1961.
[ 2 ] K.
H.Bliicher, Ph. D. Thesis, Universitat Marburg, 1961.
131 K. Dimroth, Angew. Chem. 72, 331 (1960).
Azulenes from Pyrylium Salts and Wittig Reagent
By Prof. Dr. K. Dimroth, Dr. K. H.Wolf, and H.Wache
Starting out from cyclopropane- I ,2-dicarboxylic anhydride
( 1 3 and from the corresponding ci.s- and rrans-3-methyl anhydrides [ ( l h , cis), m . p . 91 " C , and (/&, trnns)] treatment
with benzene in the presence of AIC& gave the I-benzoylcyclopropane-2-carboxylicacids (2) with the benzoyl group
cis to the carboxyl group [(2a), n1.p. 146°C; (2&, cis), m.p.
195 "C; (2b, trans), m.p. 135"Cl. Condensation of (2) with
hydrazine gave the pyridazinone derivatives (3) [(3a), m. p.
165 "C; (3&,cis), m.p. 191 " C ; (.<I>,rrtms), m.p. 174"CI.
Chemisches Institut der Universitit
Marburg/Lahn (Germany)
Pyrylium salts (I) normally yield benzene derivatives with
triphenyl methylene phosphorane (2) [l]: in this way, 2,4,6triphenylpyrylium fluoroborate (or perchlorate) and (2)
condense in the presence of t-butoxide in t-butanol or in a
little acetonitrile to form 1,3,5-triphenylbenzene, 2,3,4,6tetraphenylpyrylium salts give tetraphenylbenzene (m.p.
217-218 "C), and pentaphenylpyrylium salts give pentaphenylbenzene (m.p. 246-248 "C).
1
Reaction of (3.) with phenyl-lithium yielded (4a), m.p.
196 "c(decornp.); (4.) is a derivative of dkdiZdnOrCaradiene
as follows from its infrared spectrum (no N H band, C= N
double bond band at 1545 cin.1) and N M R spectrum
(10 aromatic and 4 aliphatic protons; the latter gave a n
AB2X spectrum: TA = 7.91; '13
7.38; TX = 9.77; JAB =
9.0 cps; JAX = 3.5 cps; JBX =- 4.8 cps), and also from the
fact that (4n) isomerizes with acit1.1 l o (k),
imp. 135 "C.
(46,
Angew. Chem. internat. Edit.
I
Vol. 2 (1963) { No. I0
cisJ
( 4 6 , ttcms)
62 1
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