close

Вход

Забыли?

вход по аккаунту

?

On the Aggregation of Lithiated Bicyclobutane Derivatives in Solution.

код для вставкиСкачать
-80°C: 6 S n = -258.0 (quin, t, J=776, 102 Hz).-+3O0C: -258.9 (sept,
/ = 5 5 1 Hz).
171 H. H. Karsch, A. Appelt, unpublished.
181 Yellow, air-sensitive crystals (pentane), m.p. =93-94"C.-NMR
(C,D,CD,, 3OOC): 6"P= -22.7 (s); G""Sn= - 175.4 (quin, J = 7 3 7
Hz).-( -30°C): no significant change.
[Y] C,,H,,P,Sn, M=508.98, P2,; a=6.540(2), h = 16.338(6), c = 1 l.720(4) A,
p=98.15(3)".
V = 1239.64A1, p,,,,,,,=1.363
g/cm' for Z = 2 at
T = - 3 5 ° C . 4327 independent reflections of which 162 are unobserved
(1<2.0u((I)), t h , + k , ?I. and Friedel reflections, ( ~ i n $ / A ) ~=, ~ ~
0.593 k ' ,
F(000)=520, Mo,,-radiation, A =0.71069 A, w-scans, Syntex
P2,). Empirical absorption correction @(Mo,,,)= 14.1 I cm-'), based on
ly-scans of six reflections; Patterson methods; R =0.038, R, =0.043,
w = ! i / 0 2 ( F , , ) , k = 1.72 in the last cycle (non-H-atoms anisotropic, Hatoms constant, 189 parameters, I block, SHELX 76); & , F , n , =
1.691
- 2.09 el,&'. Further details of the crystal structure investigation are
available on request from the Fachinformationszentrum Energie Physik
Mathematik, D-7514 Eggenstein-Leopoldshafen 2, on quoting the depository number CSD 51 179, the names of the authors, and the journal citation.
a)
a0
81
+
A
On the Aggregation of Litbiated
Bicyclobutane Derivatives in Solution**
79
-6
B
+
$
i'
By Arnulf-Dieter Schliiter,* Helmut Huber, and
Giinter Szeimies
The degree of aggregation of organolithium compounds
in solution can easily be established by determination of
the '3C-6Li-NMRcoupling pattern."' Fruenkel et aLLZa1
and
Seebuch et a1.,'2h1in particular, obtained a wealth of infor-
R2
R'
R2
R'
1
R2
R2
R'
6
5
4
R2 Li
R'
8
7
1 - 7 a
b
c
d
e
R'
H
6Li
Li
0
SiMe,
R2
H
H
Li
D
SiMe,
mation about the structure of monolithiated compounds
from low-temperature I3C-NMR spectra. We report here
on the aggregation behavior of the mono- and dilithiated
bicyclobutane derivatives lb-4b and 5c, respectively, in
tetrahydrofuran (THF).[315c, like the still controversial 1,2d i l i t h i ~ e t h a n e , 'is~ ~a saturated, vicinally dilithiated hydrocarbon.
The bicyclobutanes la-4a were lithiated at C-1 with
one molar equivalent of nBu6Lif2b1
in ether at 20°C. After
removal of the solvent,'51a ca. 3 M solution of the "anion"
in THF/[D,]benzene was prepared with the oily or pow[*] Dr. A,-D. Schliiter, H . Huber, Prof. Dr. G. Szeirnies
lnstitut fur Organische Chemie der Universitat
Karlstr. 23, D-8000 Munchen 2 (FRG)
I**]
404
Fig. I . a) The C-l signal o f [hLi]l-Iithi~benzvalene4b in the "C-NMR spectrum at -76°C after 300 pulses; ca. 3~ in THF. b) Some of the aggregations
consistent with the coupling pattern. Structure B is favored.
R2
R'
3
2
R2
R'
R'
&Li
This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0 VCH Verlaysyesellachafr mbH, 0 - 6 9 4 0 Weinheim. 1985
dery residue. The appearance of a coupling fine structure
was observed in the low-temperature I3C-NMR spectrum
beginning at - 45 "C: baseline-separated multiplets were
observed throughout the spectrum at -60°C. In all cases a
quintet with the intensity distribution 1 : 2 : 3 : 2 : 1 and a
"C-'Li coupling constant of ca. 10 Hz was obtained for
the signal of the 'Li-bearing C-atom ( l b : 10.1: 2b: 10.3;[61
3b: 9.4, 4b: 9.6; error: t 0 . 6 Hz). As shown in Figure l a by
the C-1 signal of 4b obtained by accumulation of only 300
pulses a good signal-to-noise ratio can be achieved with
natural carbon isotope distribution.
7b is present as dimer, both in the solid state"] and in solution.f2h1On the basis of the NMR data it is also reasonable to assume dimeric structures like A or B in Figure l b
for lb-4b. But trimers of type C (Fig. lb) or oligomers
with large rings cannot be ruled out. I t is remarkable that
all bridgehead lithiated bicyclobutane models examined so
far prefer the same degree of aggregation.
We next attempted to lithiate bicyclobutanes at both
bridgehead positions''' and to obtain information about
the state of aggregation of the products. The elimination of
lithium hydride from 1,w-dilithioalkanes (a=1 -n),['I an
unsolved problem in the synthesis of 1,2-dilithi0ethane,'~"]
should not occur in the case of the doubly metalated bicyclobutane since highly strained olefins of type 8 would be
formed by loss of LiH. Indeed, the hydrocarbons la-6a
could be metalated at both bridgeheads to give the "dianions" lc-6c, in each case with 2.0 molar equivalents of
nBuLi in ether at 20°C.["1 The work-up of the suspensions
thus formed with deuterium oxide and chloro(trimethy1)silane, respectively, led to ld-6d or to le-6e. The data
listed in Table 1 show that high degrees of lithiation were
obtained in a short time with those bicyclobutanes which
carry sp2-hybridized carbon atoms in the endo-,endo-annelated bridges and/or have small angles between the threemembered ring faces of the bicyclobutane moiety.
The 'H- and particularly the I3C-NMR spectra of the
"dianions"l 131 show unusually broad, unstructured bands.
05 70-O833/85/O505-O404 $ 02.50/0
Anyew,. Chein. Int. Ed. Engl. 24 (198s) N o .
S
Table I . Degree of double deuteration [I21 and silylation of the bicyclobutanrs la-6a as a measure of the lithiability of the two bridgeheads with 2.0
mole equivalents of nBuLi in ether at 20°C.
Chain-Lengthening Difunctionalization of
Grignard Compounds by Reaction with
Ketenylidenetriphenylphosphorane
Educt
la
2a
3a
4a
5a
6a
Degree of
dideuteration [Oh] [a]
I5
95
I00
-
Icl
100
95
Degree of
silylation [Oh] [b]
I
By Hans Jurgen Bestmann,* Martin Schmidt, and
Rainer Schobert
15
30
55
21 [dl
70
53
3d
3d
I d
2h
Ih
3d
The readily accessible ketenylidenetriphenylphosphorane l " l reacts with Grignard reagents 2 to give addition
compounds of still unknown structure. Such adducts,
which are best formulated as in 3, are hydrolyzed by water
to acyl ylides 4. This reaction sequence thus enables a
chain-lengthening of 2 by two C atoms with concomitant
introduction of a carbonyl function and an ylide function
with C C coupling. Together with the secondary reactions
(carbonyl olefination and saponification) a possibility is
thus opened up for the acylation of Grignard compounds,
i.e. for the conversion of Grignard compounds into various
kinds of ketones."] Table 1 shows that this new methodology can be exploited for the synthesis of a wide spectrum
of ylides 4.13'
[a] ' H - N M R spectroscopically. [b] Determined on the isolated product. [c]
The proportion of 4d could not be determined because of signal overlapping.
[d) In competition with the second metalation, 4b rearranges to phenyllithium.
Only in the case of 5c was it possible to assign all the signals."'' The cause of the drastic line-broadening is, in our
opinion, the intermolecular cross-linking. Greater contributions to the widths at half height (W,,J by dynamic effects or by spin-spin coupling are unlikely. Thus, the W1,*
values"41 change neither with variation of temperature
(-50°C to +70°C) or concentration (0.4 to 2 . 2 M ) nor
with the use of the 6Li isotope. A deaggregation of the
cross-linked structures by addition of u p to ten molar
equivalents of various donors to solutions of 5c in T H F or
ether was not accomplished.[1515c can be stored for several
days at room temperature in solution without change.
1
Received: December 10, 1984:
revised: February 19, 1985 [Z 1106 IE]
German version: Angew. Chem. 97 (1985) 406
[ I ] L. I). McKeever, R. Waack, M. A. Doran, E. B. Baker, J . Am. Chem.
SUC.YO (1968) 3244: S. Bywater, P. Lachance, D. J. Worsfold, J . Phys.
Chem. 79 (1975) 2148: F. Wehrli, J . Magn. Reson. 30 (1978) 193.
[2] a ) G. Fraenkel, P. Pramanik, J . Chem. Soc. Chem. Cummun. 1983. 1527,
and references cited therein: b) D. Seebach, R. Hassig, J . Gabriel, H e l ~ ~ .
Chm. A m 66 (1983) 308, and references cited therein.
131 For the association behavior of organolithium compounds see, e.g.: T.
L. Brown. Pure Appl. Cliern. 23 (1970) 447; J . P. Oliver, Adu. Orgonumet.
Chem. I5 (1977) 235; J. L. Wardell in G. Wilkinson, F. G. A. Stone, E.
W. Abel: Cumprehensiue Organumetollic Chemisfry. Vul. I , Pergamon
Press, Oxford 1982, p. 43.
[4] 1,2-Dilithioethane is assumed as intermediate: V. Rautenstrauch, Angew.
Chem 87(1975) 254: Angew Chem. Int. Ed. Engl. 14 (1975) 259. It seems
to us that the synthesis of 1.2-dilithioethane from lithium and ethylene
(yield ?7-300/,) or from lithium and 1,2-dihdloethane (yield 6-9%) is
not confirmed: H. Kuus, Uch. Zap. Tarfu. Gus. Uniu. 193 (1966) 130
(Cheni. Abstr. 69 (1968) 67443q); Tartu Riikliku Ulik. Tuim. 219 (1968)
245 ((%em. Ahstr. 71 (1969) 49 155j).
[5] DANGER: Undissolved 4b has a tendency to decompose explosively!
[6] We ohtained no evidence of a diastereomeric mixture.
[7J R. P. Zerger, G. D. Stucky, J . Chem. SUC.Chem. Commun. 1973, 44.
[8J 3c ha5 already been detected: I. Murata, T. Nakazdwa, M. Kato, T. Tatsuoka, Y. Sugihara, Tetrahedron Lett. 1975. 1647.
[9J See, e.g.: J. W. Seetz, G. Schat, 0. S. Akkerman, F. Bickelhaupt, J . Am.
Chem. Suc. 104 (1982) 6848: P. von R. Schleyer, A. J. Kos, E. Kaufmann. ibid. I05 (1983) 7617.
[lo] H. Bogdanovic, B. Wermeckes, Angew. Chem. 93 (1981) 691: Angew.
Chem. lnt. Ed. Engl 20 (1981) 684.
[ I I ] According to Strerfwierer's "Ion-Triplet Model", directly adjacent dianionic charges are well stabilized by two monovalent cations: A. Streitwieser. Jr., Acc. Chem. Res. 17 (1984) 353.
(121 We found that deuterolysis does not always suffice for the quantitative
detection of bicyclobutane dianions. When Sa is treated with more than
two mole equivalents of nBuLi at - 30 "C in ether, according t o the 'HNMR spectrum, 5b is formed quantitatively with no 5c present. Nevertheless, after addition of this mixture to tenfold excess deuterium oxide, up to 60% 5d is obtained.
(131 Prepared with exactly (!) 2.0 mole equivalents of nBuLi.
(141 'H-NMR ([D,]THF; W,:>values ( & 15%) in Hz (in brackets); standard:
TMS int.): 6 ~ 0 . 5 (28:
9
2 H , 2-H, 5-H), 5.94 (22; 4 H , aromat. H): "CNMR iether/[D,]benzene): 6 (+ I ppm)=43 (130: C-2: C-5). 84 ( > 190:
C - I ; C-6). 116, 122 (30; aromat. C j ; 158 (50: C-3: C-4).
[ 151 Bis(dimethylaminojethane, [12]crown-4. hexamethylphosphoric acid
triamide (-6O"C), nBuLi/potassium tert-butoxide, and dimethoxyethane.
Anyen,. Chem lnt. Ed. Engl. 24 (19K5) N o . 5
6
il
Table 1. Yields and melting points of the acyl ylides 4 obtained by reaction
of 1 with 2 and subsequent hydrolysis.
Yield
R'
4
M.p. ["CJ
Yo1
C,H,
n-C,HP
CH(CH,)-(CH>)>-CH3
(CH,),rO-tetrdhydro- I-pyranyl
(CHz),-O-tetrahydro- 1-pyranyl
(CH2).- 1,3-dioxolan-2-yl
C(CH?j=CH*
CbH,
94
85
77
65
61
60
86
65
222 (221-222 [4])
oil
oil
oil
oil
oil
148
178 (178 151)
Compounds 4, which are usually recovered as oils and
can be readily purified by chromatography, show all the
typical, strongly shifted carbonyl bands for acyl ylides beTable 2. Yields and boiling points of the ketones 6 obtained by reaction of 4
with 5 . R ' , see Tdble 1.
6
R'
Yield
la4[a1
B.p. ["C/torr]
b
CH,
CsH,
C,H,
n-C,H,
n-C,H,.
(E)-CH=CH-(CHZ)z-CHI
54
52
42
38
36
48
68- 70/13 (65.5-66110
99- 101/0. I3
136- 140/0.01
122-126/0.05 [b]
69- 71/0.01
124-12610.3
c
d
e
g
h
[S])
[a] Referred t o 4 , not optimized. [b] Kugelrohr distillation, bath temperature.
[*I Prof. Dr. H. J. Restmann, DipLChem. M. Schmidt,
Dipl.-Chem. R. Schobert
Institut fur Organische Chemie der Universitat Erlangen-Nurnberg
Henkestr. 42, D-8520 Erlangen (FRG)
0 VCH Verlagsgesellschu/t mbH. 0-6940 Wrmheim, I985
0570-0833/85/0505-0405 $ 02.50/0
405
Документ
Категория
Без категории
Просмотров
1
Размер файла
222 Кб
Теги
solutions, lithiated, bicyclobutan, aggregation, derivatives
1/--страниц
Пожаловаться на содержимое документа