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Intramolecular Interaction of Cyclopropylidene with the Bicyclo[1.1.0]butane System

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Lithium Phenylethynolate and Its Reaction with Carbony1 Compounds to Give p-Lactones
By Ulrich Schollkopf and lnga Hoppe"]
While enolates ( I ) have numbered among the most important reagents of organic chemistry for more than a century,
ynolates (2) have hitherto remained unknown although their
chemistry should certainly be no less interesting than that
of the former class of compounds. They could react both
at the oxygen and at the carbon on treatment with electrophiles.
\I 3
1\19
(1)
(21
We obtained lithium phenylethynolate ( 2 a ) by (one- or
two-step) elimination of benzonitrile from 5-lithio-3,4diphenylisoxazole ( 4 ).
C 4H,LiirHI
- 60 C
FI
L1
(31
(41
( 2 a ) can be trapped in the form of phenyl(trimethylsi1yI)ketene ( 5 ) with chlorotrimethylsilane (yield 41
b. p. 60"C/2
torr). It is unclear whether phenyl(trimethy1silyloxy)acetylene
is formed initially in a kinetically controlled reaction. The
reaction provides a facile entry to metalated ketenes"].
Reaction with aldehydes and ketones (6) affords (after protonation) the (3-lactones (9) (cf. Table 1). We formulate the
carbonyl adducts ( 7 ) ,which cyclize to the metalated (3-lactones
( 8 ) , as intermediates of this synthesis. However, a concerted
cycloaddition ( 2 a ) + (6) (8) cannot be ruled out. On treatment of ( 2 a ) with benzaldehydewe obtained (9d), the product
of a second reaction between (8) and the aldehyde. (8) can
be reacted in situ with alkylating agents to give tri- and tetrasubstituted (3-lactones [cf. ( 9 r ) and (Sf)]. As in other cases"].
the (3-lactones (9) can be decarboxylated quantitatively and
stereospecifically to the olefins (10) on heating to 140°C.
We view the reaction of alkynolates (2) with carbonyl
compounds (6), with its smooth C< linkage and cyclization
step [ ( 2 ) + (6) and (7) + (S)] as providing a favorable synthesis of (highly substituted) (3-lactones and their products
~ ~ . next aim
(olefins, (3-hydroxy carboxylic acids, e f ~ . ) [Our
is to synthesize further alkynolates (2).
--f
3-Phenyl-~-lactones( 9 )
Butyllithium (15 mmol, as 1 . 5 5 ~solution in hexane) and
then a solution of (6) (15 mmol) in T H F (10ml) are added
dropwise to a solution of (3jL41(3.3g, 15mmol) in dry THF
(25ml) at -60°C under N,. After 30 minutes' stirring at
- 60 "C glacial acetic acid (0.9 g, 15 mmol) in T H F (5 ml) is
added to the reaction mixture which is then allowed to warm
u p to room temperature before removal of the solvent by
vacuum distillation. Subsequent addition of benzene (70ml)
and standing for 2-3 h at 0°C are followed by filtration.
The solvent is removed and the (3-lactone (9) purified by
chromatography on silica gel (200g) with benzene as eluant.
In the synthesis of 196,) and ( 9 j ) hexamethylphosphoric triamide (9.0g, 50 mmol) is added at the beginning of the reaction
and benzyl bromide (2.6g, 15 mmol) is used in place of glacial
acetic acid. Alkylation is complete within about 20min.
Received: September I . 1975 [Z 310 IE]
German version: Angew. Chem. 87.814 (1975)
x,
ix
161
(7)
I
191
Table I . P-Lactoner ( 9 ) a n d olefins ( 1 0 ) prepared
[a] r r i i i i s Isomer characterized by reaction with benzylamine to give N-benzyl3-hydroxy-4.4-dimet hyl-2-phenylpentanamide.
[b] Mixture of diastereoisomers. Yield based on benzaldehyde
[c] Z form.
CAS Registry numbers
i n ) . 57015-19-7: ( 6 0 ) . 67-64-1: / 6 b J , 108-94-1: / 6 ( / . 630-19-3:
f f j d l . 100-52-7: i R ( r ) . 57015-20-0: i,Yh). 57015-21-1 : i X c ) . 57015-21-2:
/ 8 d ) . 5701 5-23-3
S. I: P o i i m i ~ i r w ,Angen. Chem. X5. 673 (1973): Angew. Chem. internat.
Edit. 1.
675 (1973): >. I . Bairkor a n d 1. F . Lursenko, Organomet. Chem.
Rev 4 6 , 355 (1970).
[2] H . K r d p w in Houben-Weyl-Miller: Methoden der organischen Chemie.
Thieme. Stuttgart 1963. 4th E d i t , Vol. 6j2, p. 556: W: Ailurn, J . Bueio,
and ./i+Chuo Lirr. J . Am. Chcm. Soc. 94, 2000 (1972).
[ 3 ] Cf. L. Prrqirrrrr. Modern Helerocyclic Chemistry. W. W. Benjamin. New
[I]
York 1968. pp. 89ff.
[4] K . Bu.\r. M . Chriri. R. Hiiis~qm. W : M a c k . and R . Su.srmrrnu. Chem.
Ber I f 1 6 3258 (1973).
Intramolecular Interaction of Cyclopropylidene with the
Bicyclo[ 1.1.01butane System[**]
By Manfred Christl and Monika Lechned']
The reaction of 7,7-dibromotetracyclo[4. l.0.0234.03.5]heptane ( / ) I i , * I and the homologous compound 8,8-dibromotetracyclo[5.1 .0.02.4.03.']octane ( 6 ) with methyllithium should
give rise to the cyclopropylidenes (2) and (7) respectively.
Treatment of ( I ) dissolved in ether with methyllithium
at - 15°C affords only a viscous oil. On working in styrene,
an approved reagent for 1,2-~yclohexadiene[~'.
it is possible
to trap ( 3 ) . We isolated 61'5;, of 9-phenyltetracycl0[5.2.0.0'~~.0~.
']non-6-ene ( 4 ) as a colorless oil, b. p. 80 to
90 "C (bath)/O.OOl torr. Apart from elemental analysis and
mass spectrometry, the structure of ( 4 ) is established by the
[*I
[*I
Prof. Dr. I:.
Schiillkopf and Dr. 1. Hoppe
Organisch-Chcmisches lnstitut der Universitiit
34 Giittingen. Tammannstrasse 2 (Germany)
Dr. M. Christl and M. Lechner
lnstitut fur Organische Chemie der Universitiit
87 Wiirzburg, Am Hubland (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
765
I
CH~LI
T
strained bicyclo[2.2.2]octa-2,5-diene derivative ( 9 ) then
suffers Diels-Alder cycloreversion to give (10).
In order to test this proposal we used 1,7-dideuterated
(5)"l as starting material to produce (13) containing a D
atom only in the para position of the phenyl ring. Apparently
the acetylenic deuterium in (10) had been replaced by hydrogen. Moreover, we synthesized ( 5 ) containing practically no
13C in position 1[']. This compound gave ( 1 3 ) having the
label uniformly distributed between the para position of the
phenyl ring and the isoxazole 4-position, as shown by the
halved intensity of the respective signals in the I3C-NMR spectrum
H&-CH=CH,
'H-NMR spectrum, displaying a signal for only one olefinic
proton (m, S=5.52ppm), and the "C-NMR spectrum, in
particular by the characteristic high field absorption of the
bicyclobutane bridgehead carbons C-3 and C-4 at 6=4.2 and
4.8 ppm.
The reaction of tricycl0[4.1.0.0~*~]hept-3-ene(5)lZ* 4l with
bromoform and potassium tert-butoxide affords 68 % of the
tetracycle (6) as a colorless liquid, b. p. 50-60°C (bath)/0.001
torr. Treatment of its ethereal solution with methyllithium
at 0°C should generate (7). The expected insertion of the
On reduction of (6) with sodium in liquid ammonia the
hydrocarbon (14) is formed, which was synthesized recently
via another routeI8]. At variance with the results of the gas
phase pyrolysis"] in [D,]-toluene/tetramethylethylenediamine solution at 210°C 114) is converted mainly into trans-tricycl0[4.2.0.0~~~]oct-7-ene
( I 5 ) , identified by its characteristic
NMR spectrum[9J.
Received: September 8, 1975 [Z 314 IE]
German version: Angew. Chem. 87. 815 (1975)
CAS Registry numbers:
11). 50399-12-7; (31. 57015-34-6: 14). 57015-35-7: is), 35618-58-7;
16). 57015-36-8: ( 7 ) . 57015-37-9; ( R ) . 35434-67-4; (10). 57015-38-0;
i l l ) , 57015-39-1: 1/21, 57015-40-4; ( 1 3 ) . 2904-75-8
M . Chrisfi, Angew. Chem. 85, 666 (1973); Angew. Chem. internat. Edit.
17J
."v3
H,C
CHa
12, 660 (1973).
M . Christ/ and G. Bruntrup. Angew. Chem. 86. 197 (1974); Angew. Chem.
internat. Edit. 13. 208 (1974).
M! R . Moore and W R . Moser, J. Org. Chem. 35, 908 ( I 970).
G. W Klumpp and J . J . Wielink, Tetrahedron Lett. 1972, 539.
Compound ( 1 0 ) is also formed from the reaction of rruns-4,4,8,8-tetrabromotricyclo[5.1.0.0"]octane,
the 2: 1 adduct of dibromocarbene to 1,4cyclohexadiene, with methyllithium; G. Szeimies and K. Munnhardt, personal communication.
M . Christ/. I / . Heinemann, and W Kristof; J . Am. Chem. Soc. Y7, 2299
( 1975).
Prepared according to ref. [2] from "C-labeled benzvalene obtained
by the method of K a t z et a / . with "CH,CI,; 7: J . Karz, E . J . M'any,
and N . Acron. J. Am. Chem. Soc. Y3, 3782 (1971); see also R. D. Suenrum
and M . D. Hurmoni,, ihid. 95, 4506 (1973).
R. 7: X i h r and 1.. A . Puyuetre, Angew. Chem. 87, 488 (1975); Angew.
Chem. internat. Edit. 14, 496 (1975).
W R. R o t h and B. Peltzer, Liebigs Ann. Chem. 6x5, 56 (1965).
2H-lJ-Thiazete: A New Heterocyclic System[**]
By Klaus Burger, Josef Albanbauer, and Manfred Eggersdorfer"]
d
i 131
carbene into the syn-C-H bond of position 6 to give (8)
fails to take place. Instead, another C8H8 isomer, namely
5-ethynyl-1,3-cyclohexadiene
is formed in about 40 Y,
yield as the product of a far-reaching reorganization. Its structure was verified on the basis of the adduct ( 2 1 ) formed
with 4-phenyl-1,2,4-triazolinedione(NPTD), m. p. 181 to
183 "C, and the duronitrile oxide adduct (12) which was dehydrogenated without purification with dichlorodicyano-pbenzoquinone to give (13), the duronitrile oxide adduct of
phenylacetylene, m p. 18Ck181 "C.
Presumably, the carbene center in (7) attacks the atom
C-4 to form a double bond with concomitant rupture of
the bonds linking C-2 and C-3 to C-4 and introduction of
a double bond between C-2 and C-3. The resulting highly
766
While the stabilizing effect of tert-butyl groups (steric stabilization) on small ring systems has been known for a long
time, little use has been made ofthestabilizingeffect oftrifluoromethyl groups (electronic stabili~ation)"~in the synthesis
of strained ring systems. We have exploited this generally
valid stabilization principle for the first recorded synthesis
of 2H-1,3-thiazete (2).
Thiocarboxamides take up two equivalents of hexafluoroacetone at - 20 to 0°C Subsequent elimination of water with
POC13/pyridine proceeds oia cyclization to give 2,2,6,6-tetra[*] Priv.-Doz. Dr. K. Burger, Dipl.-Chem. J. Albanbauer. and M. Eggersdorfer
Organisch-Chemisches Institut der Technischen IJniversitat
8 Miinchen 2, Arcisstrasse 21 (Germany)
This work was supported by the Deutsche I;orschungsgemeinschaft
and the Fonds der Chemischen Industrie.
[**I
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bicycle, intramolecular, interactiv, system, butant, cyclopropylidene
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