R.H. Neilson, W.R. Kucera / Journal of Organometallic Chemistry 646 (2002) 223–229
227
Because of the presence of two asymmetric phospho-
rus centers, 15 and 16 were formed as mixtures of
diastereomers in ca. 1:1 ratios. This is confirmed by the
appearance of two signals of similar intensity in their
31P-NMR spectra. Moreover, two sets of doubled-dou-
blets are clearly seen for the acetylenic carbons of 15
and two distinct, 8-line, ABX patterns are observed for
the diastereotopic PꢁCH2ꢁSi protons of 16.
(ca. 150 ml) was added to extract the product from the
salts. Filtration and solvent removal under reduced
pressure left a viscous brown liquid. Subsequent distil-
lation through a 3-cm column afforded the product 1 as
a colorless liquid (Tables 1 and 2). Compounds 2 and 3
were prepared in a similar manner from the respective
alkynes, HCꢀCR (R=n-Bu, CH2OCH3).
3.3. Preparation of acetylenic (silylamino)phosphine,
(Me3Si )2NP(Ph)CꢀCSiMe3 (4)
3. Experimental
By using PhPCl2 instead of PCl3 in the above proce-
dure, the intermediate chloro(phenyl)phosphine,
(Me3Si)2NP(Ph)Cl, was prepared on a 50-mmol scale.
Subsequent addition of one equivalent of LiCꢀCSiMe3,
prepared as described above, followed by a similar
work-up procedure, afforded 4 as a colorless liquid
(Tables 1 and 2).
3.1. Materials and general procedures
The following reagents were obtained from commer-
cial sources and used without further purification:
Me3SiCl, n-BuLi, PCl3, PhPCl2, (Me3Si)2NH,
Me3SiCꢀCH, HCꢀCMgCl, CH3OCH2CꢀCH, and 1-
hexyne. Hexane, THF, ether, and benzene were distilled
from CaH2 and stored over molecular sieves. The fol-
lowing reagents were prepared according to published
3.4. Preparation of acetylenic (silylamino)phosphines,
(Me3Si )2NP(R)CꢀCCH2OCH3 (5–7)
procedures:
(Me3Si)2NP(CH2SiMe3)Cl
[10]
and
(Me3Si)2NP(R)Cl (R=n-Pr, i-Pr, n-Bu) [11]. Proton,
13C-, and 31P-NMR spectra were recorded on a Varian
XL-300 spectrometer in CDCl3 solution. Elemental
analysis were performed by E&R Microanalytical Ser-
vices, Corona, NY. All reactions were carried out under
an inert atmosphere of dry nitrogen or under vacuum.
In a typical preparation, a 500 ml, 3-necked flask was
equipped with a magnetic stirrer bar, an N2 inlet, and
an addition funnel and then charged with methyl
propargyl ether, HCꢀCꢁCH2OCH3 (12.6 ml, 150 mmol)
and THF (150 ml). This solution was cooled to −
78 °C and n-BuLi (60 ml, 150 mmol, 2.5 M hexane
solution) was added dropwise. The solution was al-
lowed to warm to r.t. while stirring and was then
cooled to 0 °C. The chlorophosphine, (Me3Si)2NP(i-
Pr)Cl (40.4 g, 150 mmol) was then added slowly via the
addition funnel. The mixture was then allowed to warm
to r.t. The solvent was removed under reduced pressure
and dry hexane (ca. 250 ml) was added to extract the
product from the salts. Filtration and solvent removal
under reduced pressure left a viscous brown liquid.
Subsequent distillation through a 3-cm column af-
forded the product 5 as a colorless liquid (Tables 1 and
2). Compounds 6 and 7 were prepared in a similar
manner from the respective P-chloro(silylamino)-
phosphines, (Me3Si)2NP(R)Cl (R=CH2SiMe3, n-Bu).
3.2. Preparation of diacetylenic (silylamino)phosphines,
(Me3Si )2NP(CꢀCR)2 (1–3)
In a typical preparation, a 500 ml, 3-necked flask was
equipped with a magnetic stir bar, an addition funnel,
and a N2 inlet adapter and charged with (Me3Si)2NH
(10.6 ml, 50 mmol) and Et2O (100 ml. This solution was
cooled to 0 °C and n-BuLi (20 ml, 50 mmol, 2.5 M
hexane solution) was added slowly. After warming to
room temperature (r.t.), the solution was cooled to
−78 °C. Next, PCl3 (4.4 ml, 50 mmol) was added
slowly via the addition funnel that had first been
washed with hexane (ca. 5 ml). This solution was
allowed to warm slowly to r.t. (during which time the
reaction between PCl3 and LiN(SiMe3)2 occurs) while
stirring for about 1 h. A separate 250 ml, 3-necked flask
was equipped with a magnetic stirrer bar, an addition
funnel, and a N2 inlet adapter and charged with
HCꢀCSiMe3 (9.8 ml, 100 mmol) and THF (100 ml).
This solution was cooled to −78 °C and n-BuLi (40
ml, 100 mmol, 2.5 M hexane solution) was added
dropwise. This solution of the lithiated trimethylsily-
lacetylene was allowed to warm to r.t., transferred via
cannula to the other addition funnel, and then added
slowly to the dichlorophosphine solution at 0 °C. The
mixture was then allowed to warm to r.t. The solvent
was removed under reduced pressure and dry hexane
3.5. Preparation of the P-bromophosphoranimine,
Me3SiNꢂP(n-Bu)(CꢀCCH2OCH3)-Br (8)
A 100 ml, 3-necked flask was equipped with a mag-
netic stirrer bar, an addition funnel, and a N2 inlet and
then charged with the phosphine 7 (13.5 g, 43 mmol)
and benzene (50 ml). The solution was cooled to 0 °C
and a solution of bromine (2.2 ml, 20% excess) in
benzene (6 ml) was added slowly from the addition
funnel. Addition of the bromine solution was stopped
when the endpoint (a slight, persistent yellow color)
was reached. The solvent and Me3SiBr were removed
under reduced pressure. Distillation through a 3-cm