close

Вход

Забыли?

вход по аккаунту

?

Convenient General Synthesis of Alkynylcyclopropanes.

код для вставкиСкачать
In summary, none of the calculations yield an activation
energy and (with the exception of the MIND0/3 calculation) all predict that in the gas phase N6 is ca. lo3 kJ/mol
less stable than 3 N2. For as long as n o direct experimental
proof for the existence of N6 exists we must assume that
hexazine is neither thermodynamically nor kinetically stable.
Received: February 16, 1981 [ Z 973 IE]
German version: Angew. Chem. 94 (1982) 71
111 A. Vogler, R. E. Wright. H. Kunkely, Angew. Chem. 92 (1980) 745; Angew.
Chem. In!. Ed. Engl. 19 (1980) 717.
[2] a ) M. H. Palmer, A. J. Gaskell, R. H. Findlay, J. Chem. Soc. Perkin Trans.
I 1 1974. 778; b) J. S . Wright, J. Am. Chem. Soc. 96 (1974) 4753: c) M. S. J.
Dewar, Pure Appl. Chem. 44 (1975) 767.
[31 H. Huber, Theor. Chim. Acta 55 (1980) 117: 1. Mol. Struct. Theochem. 76
(1981) 277
[4] P. Pulay. M o l . Phys. 1 7 (1969) 197.
2,4,6-Cycloheptatrienylidenemalondialdehyde
(8,s-Diformylheptafulvene) **
By Christian ReichardP and Kyeong- Ye01 Yun
We report here on the preparation of the title compound
7, which belongs to the hitherto rarely investigated cycloalkylidenemalondialdehydes.Starting from the sodium
salt 1 of malondialdehyde, 71'01
is obtainable as orange-red
crystals (m.p. 132- 133 "C, dec.) uia the isolable intermediates 2 to 6 (Scheme I).
According to NMR spectra, 7 is in equilibrium with the
valence isomer 3-formyl-8aH-cyclohepta[b]furan
8 in solution (DzO: 100% 7; CCI,: 37% 7).
The X-ray structure analysis shows that exclusively the
valence isomer 7 exists in the crystal. As a result of steric
interactions, between 2-H/7-H on the one hand, and the
two aldehyde oxygen atoms on the other, the seven-membered ring and the malondialdehyde group are rotated
through 18.1" with respect to each other. This and the participation o f the dipolar mesomeric resonance structure 7b
lead to a relatively long C-I/C-8
bond (143 pm; C,,--C,,.
single bond: 148 pm; double bond: 134 pm).
MNDO calculations["] give a dipole moment of 3.0 D
for a partially optimized completely planar conformation
of 7. An experimental determination of the dipole moment
of 7 was not possible owing to the concomitant presence
of the valence isomer 8 in solution.
Since they cannot be enolized, 2,f-substituted malondialdehydesl'] and alkylidenemal~ndialdehydesl~~
are real
C 3 dialdehydes and therefore valuable C,-synthetic building blocks.
Received: May I I , 1981 [ Z 958 IE]
German version: Angew. Chem. 94 (1982) 69
Angew. Chem Suppl 1982. 113
[I] R. Dersch, C. Reichardt, Synthesis 1980. 940.
[ 5 ] C. Reichardt, W. Pressler. E - U . Wiirthwein, Angew. Chem. 88 (1976) 8 8 :
Angew. Chem. In/. Ed. Engl. I5 (1976) 112.
[I01 T h e constitution of 7 follows from the elemental analysis, the 'H-and
"C-NMR spectra, as well a s an X-ray structure analysis. We thank Dr.
W. Massa and R. Schmidt, Fachbereich Chemie, Universitat Marburg,
for carrying out the X-ray structure analysis.
1161 M. J. S. Dewar, W. Thiel, J. Am. Chem. Soc. 99 (1977) 4899: we thank
Dr. E.-U. Wiirthwein, Universitat Erlangen-Nurnberg, for the M N D O
calculations.
+ NaOH
H
J
L
- H2O
93%
H
2
1
J
Convenient General Synthesis of
A1kynylcyclopropanes* *
J
3
4
By Thomas Liese and Armin de Meijere*
Dedicated to Professor Oskar Glemser on the occasion
of his 70th birthday
1
J
5
6
5t
0
0
H
Q
.....
,
......'
cf
Q
*
H
7a
H
H
7b
H
8
Scheme I .
['I
[**I
Prof. Dr. C h r . Reichardt, K.-Y. Yun
Fachbereich Chemie d e r Universitat
Hans-Meerwein-Strasse, D-3550Marburg (Germany)
Syntheses with Aliphatic Dialdehydes, Part 30. This work was supported
by the Deutsche Forschungsgemeinschaft and the Fonds d e r Chemischen I n d u s t & - P a n 29: [I].
Angew. Chem. In,. Ed. Engl. 21 (1982) No. I
Although donor-, acceptor-, as well as vinyl-substituted
cyclopropanes have become established synthetic tools, alkynylcycIopr~panes[~~,
which because of the junction of a
cyclopropyl and an alkynyl group offer an interesting and
powerful synthetic potential, have not been widely recognized.
We recently found that the easily accessible I-chloro-l(trichloroviny1)cyclopropanes 1l5)react cleanly with 2
moles of n-butyllithium to give (I-chlorocyclopropy1)-substituted lithium acetylides 6 (Scheme I), which can be solvolyzed by methanol o r water to yield (I-chlorocyclopropy1)acetylenes 7 (Table I ) or trapped by a wide variety of
electrophiles EX to give acetylene derivatives 5a (Table 2).
The 1-chloro-I-alkynylcyclopropanes5 and 7 are polyfunctional molecules, and as such valuable building blocks
for organic synthesis. Among the reactions which can be
[*] Prof. Dr. A. d e Meijere, Dipl.-Chem. Th. Liese
lnstitut fur Organische Chemie und Biochemie d e r Universilet
Martin-Luther-King-Platz 6, D-2000 Hamburg 13 (Germany)
[**I This work was supported by the Fonds d e r Chemischen lndustrie a n d
the Hoechst AG.
0 Verlag Chemie GmhH, 6940 Weinheim. 1982
0 5 7 0 - ~ / 8 ~ 3 / 8 2 / 0 1 0 / - 0 0 S6 502.511/0
65
Thermal Conversion of
1,3-Cyclooctadien-S-yne into BenzocyclobuteneA Novel Isomerization on the CsHs Hypersurface**
By Herbert Meier*, Norbert Hanold, and
Heinz Kolshorn
1
R2
R
&
R4
;
R2
5
'E
7
; & RR4
H
\
\
6
Li
Scheme I . (a) 2 mol nBuLi/mol 1, Et20/n-hexane, --78°C: (b) MeOH.
THF, -78°C; (c) EX, -20 to 0°C. 1-4 h; (d) MeOH, RT.
Tdbk 1. (I-Chlorocyclopropyl)acetylenes7 from 1.
[%I [bl
R'
R?
R'
RJ
Yield
a
CHI
b [a)
CH3
CH,
H
n-CJH.,
CH,
CH,
CHI
CH,
H
+CHA-
CH,
CH,
H
H
H
CHI
H
H
82(A)
80 (B)
76 (A)
C
d
e [a]
r la]
H
CHI
82(E)
H
H
91 (B)
81 (B)
Synthesis of the first highly-strained cyclic enyne was
accomplished some time ago[". Incorporation of a double
bond into the cyclooctyne ring system considerably increases the geometric strain; insertion of two double bonds
is expected to lead to a still greater increase in strain. Figure I shows the enthalpies of formation of 1,3,5-cyclooctatriene and I ,3-cyclooctadien-5-yne calculated on the basis
of complete optimization of geometry according to the
M N D O rnethodl4]. Both molecules have a CI conformation
in the lowest energy state. cis-2-Butene (with C 2 bsymmetry) and 2-butyne (with D3d symmetry) are listed as reference systems. A characteristic feature is the large difference in the heat of hydrogenation in the cyclo-Cx- and C4systems (236 and 120 kJ/mol, respectively). The high value
for the hydrogenation of cyclooctadienyne to cyclooctatriene is ascribed to release of ring strain. The difference in
the heat of hydrogenation of the two systems ( 1 16 kJ/mol)
can be regarded as a direct measure of the geometrical ring
strain''].
[a] Mixture o f stereoisomers. [b] Isolation: A: Short-path distillation, B: Pre-
400
parative gas chromatography.
l ?
Table 2. ( I -Chloro-2,2,3,3-tetramethylcyclopropyl)acetylenederiVdteS 5a
from la.
EX
[moll [a]
CO?
- [c]
CICO?Me
5
MeSiCI
(CH,O)?SO?
C H ,COCH,
(CH+C-O
(HKO),,
n-BuBr [c]
1.1
2.5
1.1
4
lO[d]
NCS
CHSSCH i
(CH5CO):O.
8
6.5
10
I. I
[%I
E
M. p. ["C]
Yield
COOH
COOMe
159-161
-
91 (A)
85 (B)
74 (A, C)
68 (D)
83 ( C , D)
85 ( C )
67 ( C , D)
76 (D)
70 (B)
63 (D)
54 (C)
SiMe,
CH,
C(OH)(CH,),
C(OH)(CH:).
CH,OH
nEu
CI
SCH,
COCH,
68
43
58.5
I02
55
-
38
39.5
[b]
[a] mol EX/mol la. [bl Isolation A: recrystallisation, E: distillation, C: sublimation, D: column chromatography. [cl Gaseous CO: introduced. [d] Addi-
-100
J
Fig. I.Comparison of the heats o f hydrogenation of 1,3-cyclooctadien-5-yne
and 2-butyne on the basis o f calculated"' enthalpies of formation AH,.
tion of 30 mol% hexamethylphosphoric triamide necessary. [el N-Chlorosuccinimide.
performed with them are the exchange of chlorine with
other substituents (via lithiation of 5 (E=SiMe,) and consecutive electrophilic substitution), ring opening to enines
(with Lewis acids), transformation to cyclopropyl ketones
(by mercuric salt catalyzed hydration) and to cyclopropane
carboxylic acids (by ozonization).
Received: July 29, 1981 [Z 963 IE]
German version: Angew. Chem. 94 (1982) 65
Angew. Chem. Suppl. 1982, 34
(41 J. Salaun, F. Bennani, J:C. Compain, A. Fadel, J. Ollivier, J . Org. Chem.
45 (1980) 4129, and references cited therein.
[51 W. Weber, A. de Meijere, Angew. Chem. 92 (1980) 135; Angew. Chem. h i .
Ed. Engl. 19 (1980) 138: W. Weber. Dissertation, Universitat Gottingen
1980.
66
0 Verluq Chemie GmhH. 6940 Weinheim. 1982
I ,3-Cyclooctadien-5-yne 7 was obtained by thermal
fragmentation of the selenadiazole compound 6. 7 can be
converted into 8, e.9.. by reaction with tetracyclone. On
attempting to condense 7 directly into a cold trap, only
traces of the compound remained unchanged; to our surprise we isolated almost exclusively benzocyclobutene 10.
Apparently 7 is far much less stable than the isomeric 1 3 cyclooctadien-3-yne" 'I.
The conversion must take place on the S,, energy hypersurface of the CxHxhydrocarbon with a relatively low activation barrier. This behavior is reminiscent of the valence
[*I
[**I
Prof. Dr. H. Meier, N. Hanold, H. Kolshorn
lnstitut fur Organische Chemie der Universitat
Auf der Morgenstelle 18, D-7400 Tubingen (Germany)
T h i s work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0570~-0833/82/0101-0066$ 02.50/0
Angew. Chem. I n i . Ed. Engl. 21 (1982) No. I
Документ
Категория
Без категории
Просмотров
0
Размер файла
194 Кб
Теги
synthesis, general, alkynylcyclopropanes, convenient
1/--страниц
Пожаловаться на содержимое документа