close

Вход

Забыли?

вход по аккаунту

?

First Detection of a -Coupled 1 5-Diradical via Cycloaddition.

код для вставкиСкачать
Table I. Cyanation of ferr-alkyl chlorides.
ferf-Alkylchloride
Nitrile
Yield [a]
“1
First Detection of a n-Coupled 1,s-Diradical
via CycloadditionI**]
By Gerd Kaupp and Inge Zimmermann[”
2-Chloro-2-methylpropane( l o )
2-Methyl-2-propacarboni- 75 (64)
trile (30)
2-Chloro-2-methylbutane (lb)
2-Methyl-2-butacarbonitrile80
(75)
(3b)
2-Methyl-2-heptacarboni- 78 (70)
trile (3c)
5-Chloro-5-methylundecane(Id)
5-Methyl-5-undecacarboni- 80 (70)
trile (3d)
1 -Chloro-1-methylcyclopentane ( l e ) I-Methylcyclopentacarbon-75 (67)
itrile (3e)
I-Chloro-l -ethylcyclopentane (11)
I-Ethylcyclopentacarboni- 87 (82)
trile (3fl
I -Chloro- I-methylcyclohexane ( l g j
I-Methylcyclohexacarboni-60 (38)
trile (39)
I-Chloro- 1methylcycloheptane (Ih) 1-MethyIcycloheptacarbon- 85 (76)
itrile (3h)
1 -Chloro-I -methylcyclododecane (1;) I-Methylcyclododecacar- 75 (60)
bonitrile (3;)
exo-2-Chloro-2-methylnorbornane (lj) exo-2-Methyl-2-norborna- 90 (84)
carbonitrile (3j)
2-Chloro-2-methylheptane (lc)
[a] The values reflect the ‘H-NMR spectroscopically estimated amounts; the
data in brackets are the yields of isolated products. The structures of all
products were confirmed analytically and spectroscopically.
not easily accessible neopentylamines. Since tertiary alkyl
halides are infer alia conventionally accessible from ketones, the cyanation also provides a novel method for geminal dialkylation of ket~nesI*.~’.
Diradicals such as ( I ) , (2). (3)11],
etc. establish a homologous series. This has to be differentiated from a homologous series of n-coupled diradicals (4)12’,(5)13],(6),etc. We
report on a cycloaddition of the first n-coupled 1,5-diradical. Thus, the formation and cycloaddition of (8) to a keto
group competes favorably with [2n 2x1-dimerizations of
electronically excited (7).
+
Irradiation of the crystalline dienone (7). which is readily accessible from cyclopentanone and benzaldehyde, and
which is used as a cosmetic light protection agent (UV-A
range)‘,], results in formation of the spiroheterocyclic compound (9) via cleavage of the five-membered ring and subsequent cycloaddition to the C=O-bond of a second molecule of (7). Furthermore (7) dimerizes via the exocyclic
double bonds to give the dispirocyclobutanes (10) and (11).
The product ratios (9) :(lo):(11)=26 :38 : 8 do not change,
whether or not (7) is crystallized slowly from methanol, or
rapidly from dichloromethane, and whether or not air is excluded during irradiation. However, neither (9) nor (10).
but almost exclusively the head to head dimer (11) is
formed in solution (dichloromethane; h> 380 nm)Isl upon
irradiation of (7).
Ph
Procedure
\
SnCI, (25 mol%) is added slowly to a constantly stirred
solution of the terf-alkyl chloride (I0 mmol) and trimethylsilyl cyanide (2) (13 mmol) in 30 mL of anhydrous CH2CI,
at room temperature under N2. After 24-38 h the solution
is poured onto ice-water and shaken vigorously. The organic phase is separated off, the aqueous phase washed
twice with CH2CI2, and the combined organic phases
washed with a 1OYo solution of NaHC03. The solution is
dried over Na2S04,concentrated, and either distilled or recrystallized.
+Yh
Ph P h
Received: January 12, 1981,
publication delayed at the authors’ request [Z 912 IE]
German version: Angew. Chem. 93. 1075 (1981)
[ I ] R. Gompper, Angew. Chem. 76, 412 (1964);Angew. Chem. Int. Ed. Engl.
3. 560 (1964).
121 N . Kornblum, R. A . Smiley. R. K. Bluckwood. D. C. Iffland. 1. Am. Chem.
SOC.77. 6269 (1955).
[31 B. Sauille. Angew. Chem. 79, 966 ( 1967);Angew. Chem. Int. Ed. Engl. 6.
928 (1967); T.4.Hor Hard and Soft Acids and Bases Principle in Organic Chemistry, Academic Press, New York 1977.
141 K . Friedrich. K . Wullenfe/s in Z . Rappoporr. S. Porai: The Chemistry of
the Cyano Group, Wiley-lnterscience, New York 1970,p. 67.
151 L. Friedmon. H . Shechfer. J. Org. Chem. 25. 877 (1970).
161 L. I . Krimen. D. J . Cora. Org. React. 17, 213 (1969).
171 S. Hiinig, G. Wehner. Synthesis 1979. 522;J. K. Rasmussen, S. M. Heilmun, ibid. 1979. 523.
181 B. U. Trosf,Acc. Chem. Res. 7, 85 (1074);M. T. Reerz. W. F. Uuier. I .
Chutziiosifids. A. Gionnis, H . Heimbach, U.Lowe. Chem. Ber. 113. 3741
(1980). Review of methods for the preparation of compounds with quaternary C atoms: S. F. Munin. Tetrahedron 36. 419 (1980).
191 Note added in proof I n the meantime, a procedure has been reported according to which certain tertiary alcohols can be converted into nitriles,
R. Dauis. K. G. Unrch, J. Org. Chem. 46, 2985 (1981).
1018
0 Verlug Chemie GmbH, 6940 Weinheim. 1981
p %,
Ph
( 71
+
Ph.
y
‘0
(10)
(9)
ph
--
Ph
‘b
Ph
The structures and compositions of the dimers (9), (10)
(with mirror symmetry), and (11) (with rotational symmetry) were established by elemental analyses as well as by
IR-, UV-, and ‘H-NMR spectra (see Table 1). (10) and ( Z l )
are characteristically different from their centrosymmetric
stereoisomer[61.
It is unusual that several products are stereoselectively
formed with comparable yields upon irradiation of crystalline (7) (cf. e.g.I6]; further products which appeared in
yields of <4% were not investigated). The formation of (9),
[‘I Prof. Dr. G. Kaupp,
[‘*I
I. Zimmermann
Chemisches Laboratorium der Universitat
Albertstrasse 21, D-7800Freiburg (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie and the Wissenschaftliche Gesellschaft
Freiburg i. Br. We thank Dr.D. Hunkler for recording the NMR spectra.
0570-0833/81/1212-1018 $02.50/0
Angew. Chem. h t . Ed Engl. 20 (1981) No I 2
Table I . Melting points, IR-, UV- and 250MHz-IH-NMR data of the compounds 19). (10). and (11).
Cpd.
(9)
(10)
Mp
["Cl
'H-NMR
(CDCI,, &value, J [Hzl)
284-285
256-257
7.42-7.26 (IOH, m); 7.17-6.91 (14H, m); 4.18 (2H, s); 2.39 (4H. s); 1.84(2H, s)
7.58 (2H, 1, J=2.5); 7.55-7.49 (4H, m); 7.44-7.34 (6H, m); 7.33-7.19 (6H, m);
7.09-7.03 (4H. m); 4.43 (2 H, s); 2.74-2.65 ( 4 H , dAA'BB', J=2.5); 2.43-2.35 (4H.
BBAA)
7.53 (2H, t, J=2.5); 7.45-7.14 (20H, m); 4.62 (2H, 5); 2.81-2.67 (2H, m); 2.582.47 (2H, m); 2.45-2.26 (2H. m); 1.65-1.36 (2H, m)
la1
(11)
156-157
la1
308 (4.51), 314 (sh)
314 (4.74), 320 (sh)
1720, 1700
1690
1625
1610
303 (4.66). 315 (sh),
322 (sh)
1695
1625
[a] Centrosymmetric stereoisomer o f ( l 0 ) and f l l ) :M.p.=250.5-25ISoC; 6 e 7 . 3 4 (22H, m); 4.50 (2H, s); 3.1-2.6 (6H. m); 2.0-1.5 (2H, m) [6].
which gives preparatively good yields, is the first example
of addition of a n-bond to a a-bond of a five-membered
ring. Usually such [2a+ 2n]-additions proceed only if cyclopropane derivatives are involved, oia intermediates of
type (I) or (4)12.71.
Therefore, it should be pointed out that
upon light absorption the short-lived diradical (8) is
formed in proximity to trapping molecules (7). which are
apparently favorably oriented. There is n o interfering solvation envelope which has to be penetrated prior to the
trapping by (7) to produce (9). This, and the fact that no
solid-state E/Z-isomerizations are observed suggest that
further (also homologous) intermolecular additions of diradicals to double bonds upon irradiation of suitable crystals shoufd be investigated. These should include intermolecular [20 2n]-additions of alkenes to non-additionally
strained cyclopropane derivatives"d.21,or to cyclopropane
itself, which failed in solution.
+
Procedure
(7) (1.04 g, 2.0 mmol) is evenly spread on the inner wall
of a mirrored Dewar vessel (diameter 14 cm, height 20 cm)
with some dichloromethane. After heating to 80°C for I h
the crystalline film is irradiated from within for 3.5 h at
30-35 "C using a mercury high-pressure lamp (Hanovia,
450 W) through a 5% solution of benzophenone in benzene
(5 mm; h>380 nm). From the 'H-NMR-analysis are
formed 400 mg (38%) (lo), 275 mg (26%) (9), and 85 mg
(8%) (11). By preparative TLC (200g SOz, dichloromethane) and by crystallization (1,2-dichloroethane, toluene,
and methanol, resp.) these products are isolated, purified,
and separated from 190 mg (ISYO) of unreacted (7) and byproducts.
Carbene-Analogous Germylenes (Germandiyls):
Singlets or Triplets?The First Stereospecific Cycloadditions of R2Ge
to Conjugated Dienest**]
By Michael Schriewer and Wilhelrn P. Neurnann"]
Singlet carbenes add stereospecifically, triplet carbenes
non-stereospecifically to olefins. Much less is known about
silylenes R2Si in this respect, discussions are still continuing[']. No experiments, however, have been reported concerning the singlet-triplet problem of germylenes R2Ge
until now.
The smooth thermal generation of 7-germanorbornadienes, e.g. (I). enables germylenes to be obtained at
70- 150"C[31. We now examined whether germylenes
obtained in this way e.g. dimethylgermylene (2) reacts
as a singlet or triplet in 1,4-additions to conjugated
dienesl4].
Reaction of (2) with (E,E)-l,4-diphenylbutadiene (3)
gave exclusively the cis-adduct ( 4 4 (Table I), whose dehydrogenation leads to (5). The trans-isomer (4b) is not
formed. The isomerization (4a)+ (4b) is observed only
upon UV irradiation of pure (4a).
Received: April 28, 1981 [ Z 914 IE]
German version: Angew. Chem. 93, 1107 (1981)
~
[I] a) S. L. Buchwalter. G. t.Closs. J. Am. Chem. SOC.97, 3857 (1975); b) G.
Kaupp. H.- W.Griiter. Angew. Chem. 92, 735 (1980); Angew. Chem. Int.
Ed. Engl. 19. 714 (1980); G. Kaupp. E. Teufel, H . Hopf, ibid. 91. 232
(1979) and 18. 215 (1979), and references cited therein; M . V. Encinas. J .
C . Scaiano, J. Chem. SOC.Perkin Trans. I1 1980. 56; c) K . W . Ho, P. d e
Mayo. J. Am. Chem. SOC. 101. 5725 (1979); d) P. G. Gassman. Acc.
Chem. Res. 4. 128 (1971); e) T. Martini. J. A . Kampmeier, Angew. Chem.
82. 216 (1970); Angew. Chem. Int. Ed. Engl. 9. 236 (1970).
[2] R . K . Siemionko, J. A . Berson, J. Am. Chem. SOC.102, 3870 (1980): P.
Dowd. G. Senqupra, K . Sachdeu, ibid. 92, 5726 (1970).
[3l W . R . Roth, M . Biermann. G. Erker. K . Jelich. W.Cerhartz, H. Corner.
Chem. Ber. 113. 586 (1980).
[41 D. Vorlander, K . Hobohm, Ber. Dtsch. Chem. Ges. 29, 1836 (1896): R .
Mayer, Chem. Ber. 88, 1853 (1955); G. Konrad, H . Moeller, DOS
2728241 (1979). K. Henkel G.a.A.; Chem. Abstr. 90, P142073h (1979).
151 78% yield at 8G% conversion. In tetrahydrofuran only (E.Z)-/7) seems to
be formed: H. George, H . J. Roth. Tetrahedron Lett. 1971. 4057.
[6] G . C . Forward. D. A . whiting. J. Chem. SOC.C 1969, 1868.
171 a) H. Prinzbach, D . Hunkler. Chem. Ber. 106, 1804 (1973); b) D. Kaufmann, A . d e Meyere. Tetrahedron Lett. 1974. 3831, and references cited
therein; four-membered ring addition: M. Sindler-Kulyk, W.H. Loarhouen. J. Am. Chem. SOC.98, 1052 (1976); additions of oxiranes (aziridines)
uia carbonyl ylides or azomethine ylides: K . Maruyama. A . Osuka. Chem.
Lett. 1979. 71; R . Huisgen, Angew. Chem. 89. 589 (1977); Angew. Chem.
Int. Ed. Engl. 16. 572 (1977).
Angew. Chem. Int. Ed. Engl. 20 (t98lJ No. 12
(4hl
( l a ) , R = CH3
Similarly, pure (E,E)-3,4-diphenyl-2,4-hexadiene(6) and
(2), generated from (la), give only the cis-product (7a) (Table 1) and n o detectable amounts of the trans-isomer
(76).
The stereospecific preparation of (46) or (7b), respectively, starting from the corresponding ( 2 , E ) isomers (3) or (6)
was unsuccessful. The use of (E.Z)-l-phenyl-l,3-pentadiene also gave no reaction.
['I
[*'I
Prof. Dr. W. P. Neumann, DipLChem. M. Schriewer
Lehrstuhl fur Organische Chemie I der UniversitBt Dortmund
Otto-Hahn-Str., D-4600 Dortmund 50 (Germany)
M. Schriewer, Dissertation, UniversitBt Dortmund, in preparation.
This work was supported by the Deutsche Forschungsgemeinschaft.
0 Yerlag Chemie GmbH. 6940 Weinheim. 1981
0570-0833/81/1212-l019 $02.50/0
1019
Документ
Категория
Без категории
Просмотров
0
Размер файла
230 Кб
Теги
diradical, cycloadditions, first, detection, coupled, via
1/--страниц
Пожаловаться на содержимое документа