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Homologation of Cyclic Ketones by Isocyanomethyllithium.

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The phases of 240 reflections with E > 1.6 were determined
by Karle and Karle's symbol addition method[31.Fourier
synthesis calculated with these E values and phases led to
a complete structural model which has so far been refined
to an R factor of 0.12 by Fourier syntheses and LSQ calculation~[~!
The unit cell contains two pairs of symmetry-independent
centrosymmetric molecules at two-fold special positions.
The mean values of the bond lengths and bond angles of
the two molecules are given ia Fig. 1. Standard deviations
for the bond lengths are 0.015 A and for the bond angles 1'.
dialkyl esters of phosphoramidic acid (2) with chlorine in
aqueous, acetate-buffered solution.
We found that the diethyl ester of ( I ) is obtained in the
form of a stable compound after distilling the reaction
mixture and that its preparation does not present any
problems, even on a kg scale.
Preparation of compound ( I ) , R=CH,, on a 0.5-mole
scale also proceeded in accordance with expectations. When
working with 1.5 mole of starting material, on the other
hand, a violent detonation took place after the reaction
had gone to completion and after the mixture had been
stirred for one hour.
The essential difference between the two preparations lay
in the longer reaction time required when 1.5 mole of the
starting material was reacted (6 hours as compared with
2 hours). It may be assumed that under these conditions
either the amide (2),R=CH,, or the N,N-dichloroamide
( I ) , R = CH,, undergoes partial hydrolytic cleavage of the
P-N-bond, possibly leading to the formation of explosive
nitrogen-chlorine compounds.
[139511
I
Fig. 1. Bond lengths and bond angles of (1)
The four-membered ring of ( I ) contains, within experimental error, sides of equal length (1.46A)and angles of
93 and 87 '.The C-N bond lengths indicate a high doublebond character. The C-C
bonds between the fourmembered ring and the ester groups are shortened.
The four-membered ring is planar within experimental
error. Unlike the amino groups, the ester groups are displaced by about 20" from the plane of the four-membered
ring.
Received: March 15, 1971 [Z 395 IE]
German version: Angew. Chem. 83,489 (1971)
[I]R . Gompper and G . Seyboid, Angew. Chern. 80,804 (1968); Angew.
Chem. internat. Edit. 7,824 (1968); M . Neuenschwander and A . Nieder-
hauser, Helv. Chim. Acta 1970, 529.
[2] We thank Dr. G. SeyboId and Prof. R. Gompper for provision of
the crystals sealed in capillaries.
[3] J . Karle and I.L. Karle, Acta Crystallogr. 21, 849 (1966).
[ 4 ] W R . Busing, K.O. Martin, and H . A . Lecy, ORFLS, a Fortran
Crystallographic Least Squares Program, ORNL-TM-305, 1962.
Dimethyl N,N-DichlorophosphoramidateA Warning
By Hans Dieter Block and Reinhard SchliebsI']
Zwierzak et al."] synthesizeddialkyl esters of N,N-dichlorophosphoramidic acid ( I ) by treating the corresponding
Zwierzak[21himself never observed any explosive decomposition of ( I ) , R=CH,; but on the other hand he never
carried out any preparations using more than 0.15 mole.
It therefore seems advisable not to use amounts greater
than about 0.2 mole when synthesizing ( l ) ,R=CH,, to
keep the reaction time short and to observe the usual
precautions for working with explosive substances.
Received: April 2,1971 [Z 410 IE]
German version: Angew. Chem. 83,537 (1971)
[I] A . Zwierzak er a]., Angew. Chem. 80, 285 (1968); Angew. Chem.
internat. Edit. 7, 292 (1968)
[2] A . Zwierzak, personal communication
Homologation of Cyclic Ketones by
IsocyanomethylIithium[
By Ulrich Schollkopfand Peter Bohine[*l
Isocyanomethyllithium (2),which is obtained from methyl
isocyanide and butyllithium in tetrahydrofuran"], provides
a method of introducing aminomethyl groups into carbony1 compounds conveniently and in good yield^[^.^!
From cycloalkanones one thus obtains I-(aminomethyl)I-cycloalkanols which, inter alia, are important as starting
materials for Tiffeneau-Demjanov ring expansion[51.For
example, cyclohexanone ( I ) and (2) afford I-(isocyanomethyl)-I-cyclohexanol (77% yield), which is converted
by methanolic hydrogen chloride into the amine hydrochloride ( 4 ) (>63%). Diazotization with sodium nitrite
in aqueous acetic acid then yields the intermediates ( 5 )
and (6) and finally cycloheptanone (7). I-(Isocyanomethyl)
derivatives are obtained from cycloheptanone and cyclododecanone in 95% and 90% yield, respectively, and thence
the amine hydrochlorides in about 80% and 67% yields
respectively.
[*] Dr. H. D. Block and Dr. R. Schliebs
Anorganisch-wissenschaftliche Abteilung
Farbenfabriken Bayer A G
509 Leverkusen (Germany)
Angew. Chem. internal. Edit. 1 Vol. 10 (1971) / N o . 7
[*] Prof. Dr. U. Scholikopf and P. Bohme
Organisch-Chemisches Institut der Universitat
34 Gottingen, Windausweg 2 (Germany)
49 1
water ( 5 mi)"'. The mixture is left for 24 h and then allowed
to come to room temperature, neutralized with NaHCO,,
and extracted with ether (3 x 70 ml). The extracts are
This homologation could be more profitable than the
route uia the cyanohydrinrs*61
or the nitromethyl adductI5.'t
because the reaction of the ketone with (2) is irreversible
U+
Li-CHZ-N=C
-c>""
r addition
AH@
CH,OH/HCI
~
ocH2
(2)
(3)
and the catalytic hydrogenation is replaced by a simple
methanolytic process''].
Cycloheptanone (7) from cyclohexanone (1) :
Butyllithium (0.1 mol; 40.9 ml of a 2.45 N solution in
pentane, cooled to -70°C) is added dropwise to a stirred
solution of methyl isocyanide (4.1 g, 0.1 mol) in anhydrous
tetrahydrofuran (150 ml) kept under nitrogen at -60°C.
Cyclohexanone ( I ) (0.1 mol, 9.8 g) is added dropwise to
this solution at such a rate that the temperature does not
rise above - 55°C. After ca. 10 min glacial acetic acid
(0.1 mol, 6 g) in tetrahydrofuran (I0 ml) is dropped in,
and the mixture is poured into ice-water (300ml) and
extracted with ether (3 x 100 ml). The ethereal extracts are
dried over MgSO, and freed from solvent at waterpump vacuum (rotary evaporator). There remains the
compound (3) (10.7 g, 77%) as a yellow oil, b.p. 80°C/
0.1 torr. IR spectrum (film): 2145 cm-' (vNC); 3440cm-'
(v 0 H).
Crude (3) (2 g, 14.4 mmol) is added portionwise (violent
reaction !) to a solution of gaseous hydrogen chloride
(2 g)inmethanol(lO ml), then after 24hat room temperature
precipitation is effected by addition of ether (first ca. 50 mi,
to provide crystals, and then a further ca. 100ml). This
provides in all 63% (1.5 g) of ( 4 ) as white platelets, m.p.
211°C. On concentration of the mother liquor a further
amount of ( 4 ) is obtained but this contains traces of ( I )
and is discarded.
The salt ( 4 ) (1.65 g, 10 mmol) is dissolved in water (15 ml)
and glacial acetic acid (3 ml) and treated, under cooling
by ice-salt, with a solution of NaNO, (1.04g, 15 mmol) in
[l] Syntheses with a-Metalated Isocyanides, Part 11.-Part 10:
U . Schiillkopfand R. Schroder, Angew. Chem. 83, 358 (1971); Angew.
Chem. internat. Edit. 10,333 (1971).
[21 Cf. (1. Schaiikopfand F. Gerharr, Angew. Chem. 80, 842 (1968);
Angew. Chem. internat. Edit. 7, 805 (1968).
[3] Cf. W Boll, F . Gerhart, A. Nurrenbach, and U. Schollkopf; Angew.
Chem. 82,482 (1970); Angew. Chem. internat. Edit. 9,459 (1970).
[4] P. Eohme, Diploma Thesis, Universitat Gottingen. For a synthesis
of 1-amino-2-alkanois by way of oxazolines see U . Schdllkopf; Angew.
Chem. 82, 795, 804 (1970); Angew. Chem. internat. Edit. 9, 763, 772
(1970).
[5] P. A . S. Smith and D.R. Baer, Org. Reactions 11, 157 (1960).
[6] For the dimculty of preparing cyanohydrins of, e.g., cycloalkanones
of medium ring size see L. Ruzicka, P. L. A. Plattner, and H . Wild,
Helv. Chim Acta 28, 613 (1945), and Y: Prefog and M . Kobelt, ibid. 32,
1187 (1949).
[7] Cf. Organic Syntheses, IV, 221 (1963).
[8] For an improved conversion of cycloheptanone to l-aminomethyl1-cycloheptanol uin the epoxide cf. E . J . Corey and M . Chajkousky,
J. Amer. Chem. SOC.87,1353 (1965).
492
(4)
dried over MgSO, and freed from solvent, affording the
product (7) (0.8 g, 71.5%). IR spectrum (film): 1699cm-'
(vCO), identical with that of an authentic specimen.
Received: March 24, 1971 [Z 402 IE]
German version: Angew. Chem. 83,490 (1971)
Synthesis of the Sex Attractant of Ectocarpus
siiiculosus[**l
By Lothar Jaenicke, 'TimothyAkintobi, and Dieter G .MiilIer[*l
The sperm attractant (sirenin) of the female gametes ofthe
brown alga Ectocarpus siliculosus is a hydrocarbon C , lH,,
having the structure of an all-cis-l-(cyclohepta-2',5'dieny1)but-I-ene ( I ) [ ' ] .
It has a center of asymmetry at the branching carbon atom.
On account of the very small amounts of substance formed
and given off by the sexually receptive female algae for a
short time during the state of maturity, the optical rotation
could not be determined. Considering its volatility, we
ascribe to the compound the spherical (S)-structure ( I ) [ * ] .
The compound is closely related to the dictyopterenes
recently isolated by Moore[31from the marine alga Dictyopteris. These substances are cyclopropane derivatives,
C , 1H16,
that can be converted into the corresponding
cycloheptadienes by the Cope rearrangement, given the
appropriate conformation of the cis-trans-isomers. In contrast, Ectocarpus gives off sirenin directly as the cycloheptadiene : Fractions of sirenin processed very carefully
below room temperature do not display UV absorption
above 200 nm and show the same NMR spectrum as the
gas-chromatographically purified substancecz1.In particular, there is no indication of a cyclopropane structure
between T = 8.8 and 9.7 in the NMR spectrum.
In the meantime we have synthesized the racemate of the
all-cis-l-(cycIohepta-2,5-dienyl)but-l-eneusing the following method ; Ethyl cis,trans-2-vinylcyclopropanecarboxylate is prepared from diazoacetic ester and butadiene
by the method of V ~ g e l ~
Reduction
~].
to the carbinol by
lithium alanate followed by oxidation with MnO, gives
the cis,trans-2-vinylcyclopropanecarbaldehyde(2) which
[*] Prof. Dr. L. Jaenicke and DipLChem. T. Akintobi
Institut fur Biochemie der Universitat
5 Koln, An der Bottmiihle 2 (Germany)
Dr. D. G. Miiller
Max-Planck-Institut fur Ziichtungsforschung
5 Koln-Vogelsang, Egelspfad (Germany)
[**I
The work was supported by the Fonds der Chemischen Industrie.
Angew. Chem. internal. Edit. / Vol. 10 (1971) J No. 7
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