V. P. Morgalyuk et al.
Bull. Chem. Soc. Jpn. Vol. 85, No. 1 (2012)
97
solutions is dependent on the present of nucleophilic reagents
(for example P-nucleophiles). In the absence of nucleophilic
reagents 1a reacts with itself to form only 6).
diphenylphosphinite anion (8) upon dissolution, and it can be
easily prepared in high yield from available initial compounds.9
Experimental
The Reactions of Chloro(dimethylamino)(diphenylphos-
phinoyl)methane (1a) with Electrophilic Substrates. Un-
fortunately, the diphenylphosphinite anion16c (8) is not detected
in the 31P NMR spectra of reaction mixtures. Therefore, to
confirm the possibility of existence of nucleophilic anion 8 in
reaction medium, compound 1a was also reacted with acetone,
acetaldehyde, phenyl isocyanate, dimethylformamide dimethyl-
acetal, triethyl orthoformate, bis(diethylamino)methane, and
acetonitrile complex palladium(II) chloride which behave as
electrophilic substrates.
1H and 31P NMR spectra were recorded on a Bruker Avance
300 spectrometer operating at 300.11 and 121.50 MHz with
tetramethylsilane (TMS) as an internal standard, respectively.
1
The 31P and H NMR spectra of individual compounds were
obtained in CDCl3, 31P NMR spectra of reaction mixtures were
recorded also in CHCl3 using 85% H3PO4 as an external
standard. 13C NMR spectrum of compound 3 was recorded on a
Bruker Avance 300 spectrometer operating at 75.47 MHz with
tetramethylsilane (TMS) as an internal standard.
In all cases, compound 1a reacted as it was expected from
the assumption of the existence of diphenylphosphinite anion
(8). The reactions resulted in 2-(diphenylphosphinoyl)propan-
2-ol18 (15), 1-(diphenylphosphinoyl)ethan-1-ol19 (16), N-phen-
yl(diphenylphosphinoyl)formamide20 (17), (dimethylamino)-
(diphenylphosphinoyl)methoxymethane (18), diethoxy(diphen-
ylphosphinoyl)methane3i (19), (diethylamino)(diphenylphos-
phinoyl)methane21 (20), and cis-dicholoridobis(hydroxydiphen-
ylphosphane)palladium(II)22 (21), respectively (Scheme 7).
The isolated compounds 15-20 are the products of addition
of diphenylphosphinite anion (8) to the electrophilic carbon
atoms of the reactants (compounds 15, 16, and 17) or
corresponding substitution products (compounds 18, 19, 20,
and 21); this fact provides evidence for the existence of
diphenylphosphinite anion (8) in the reaction mixture. This, in
turn, confirms the dissociation of 1a with C-P bond cleavage
(Scheme 5).
Syntheses of earlier published compounds 4,3k 6,3k 9,16 12,17
15,18 16,19 17,20 19,3i 20,21 and 2122 by reactions of compound
1a with diethyl trimethylsilyl phosphite, diethyl phosphite,
diphenylphosphine oxide, N,N-dimethylaniline, amines, water,
alcohols, acetone, acetaldehyde, phenyl isocyanate, dimethyl-
formamide dimethylacetal, triethyl orthoformate, bis(diethyl-
amino)methane, and acetonitrile complex palladium(II) chlo-
ride (see Supporting Information).
Chloro(dimethylamino)(diphenylphosphinoyl)methane
(1a).10
Dimethylformamide (0.53 mL, 0.5 g, 7 mmol) was
dissolved in 3 mL of toluene at ambient temperature. Phenyl-
phosphonic dichloride PhP(O)Cl2 (0.03 g, 0.15 mmol) was
added in inert gas atmosphere with stirring; after 20 min,
0.4 mL (0.5 g, 2.3 mmol) of chlorodiphenylphosphine (Ph2PCl)
was added. After 3 h, the reaction mixture became red-brown
and precipitation of analytically pure compound 1a began,
which completed after 18 h. The resulting precipitate was
separated by filtration, washed with toluene (3 © 5 mL) and
dried in vacuum24 to give 0.61 g (91%) of compound 1a as
colorless needle-like crystals, mp 92-94 °C dec.9 The com-
pound is highly hygroscopic. 31P NMR (121.50 MHz, CDCl3,
25 °C, 85% H3PO4): ¤ 22.80 (d, 2JP,H = 11 Hz). 1H NMR
(300.11 MHz, CDCl3, 25 °C, TMS): ¤ 8.00-7.93 (m, 4H, o-H,
Conclusion
The reactions of 1a with P-nucleophiles (and N,N-dimethyl-
aniline), amines, 0.5 equivalents of water, with itself, and
electrophilic substrates confirm a complete dissociation of
compound 1a in solutions (Scheme 5). Therefore, we can
explain the ambident reactivity of compound 1a (and chloro-
(dialkylamino)(diphenylphosphinoyl)methanes 1 correspond-
ingly) as follows.
With nucleophiles and nucleophile substrates, the reactant
is the initial molecular form of 1a, and/or (dimethylamino)-
(diphenylphosphinoyl)methyl cation (11); it behaves as an
electrophilic substrate to give corresponding products of
nucleophilic displacement (compounds 4-6 and 9) in the
chloro(dimethylamino)methyl group of 1a.
2
Ph), 7.89 (d, JP,H = 11 Hz, 1H, P-C-H), 7.56-7.49 (m, 6H,
m- and p-H, Ph), 3.08 (s, 6H, N(CH3)2). Found: C, 61.44; H,
5.79; N, 4.68; P, 10.40%. Calcd for C15H17ClNOP (293.74): C,
61.34; H, 5.83; N, 4.77; P, 10.55%.
(Dimethoxyphosphinoyl)(dimethylamino)(diphenylphos-
phinoyl)methane (5). Dimethyl phosphite (1.5 mL, 2.25 g,
20 mmol) was added to a solution of 0.3 g (1 mmol) of
compound 1a in 1.5 mL of CH2Cl2 with stirring. The mixture
was allowed to stand for 18 h at 20 °C, diluted with 10 mL of
CH2Cl2, and washed with water (4 © 5 mL). The organic layer
was separated and dried with K2CO3. The drying agent was
separated by filtration, washed with CH2Cl2 (2 © 5 mL), and
the filtrate was concentrated to about 1 mL. The concentrate
was diluted with 8 mL of hexane and the resultant precipitate
was reprecipitated twice from CHCl3-hexane to give 0.31 g
(84%) of compound 5 as colorless needles, mp 134-135 °C;
31P{1H} NMR (121.50 MHz, CDCl3, 25 °C, 85% H3PO4): ¤
26.36 (d, 2JP,P = 36 Hz, 1P, Ph2P(O)-), 23.75 (d, 2JP,P = 36 Hz,
1P, (CH3O)2P(O)-); 1H NMR (300.11 MHz, CDCl3, 25 °C,
TMS): ¤ 7.98-7.84 (m, 4H, o-H, Ph), 7.50-7.43 (m, 6H, m- and
With electrophilic substrates, the reacting species is diphen-
¹
ylphosphinite anion Ph2PO (8) that behaves as a nucleophile
to afford corresponding addition/substitution products (com-
pounds 15-21).
¹
The ease of Ph2PO (8) to undergo addition to electrophilic
substrates indicates that 1a in fact is a hidden form of
diphenylphosphinite anion (8). This allows us to recommend
application of 1a in organic synthesis as a synthetic equivalent
(synthon) of diphenylphosphinite anion (8). (Examples of
compounds capable of generating diphenylphosphinite anion
(8) in reaction medium are known from the literature. However,
this process requires either lithiation of the initial compound at
low temperature7b,7e or addition of NaI on heating.23 Compound
1a is devoid of these drawbacks. 1a spontaneously produces
2
2
p-H, Ph), 3.91 (dd, JP,H = 22.5 Hz, JP,H = 16.9 Hz, 1H, P-C-
3
3
H), 3.79 (d, JP,H = 9 Hz, 3H, CH3-O), 3.56 (d, JP,H = 9 Hz,
3H, CH3-O), 2.50 (d, JP,H = 2.4 Hz, 6H, N(CH3)2). 13C NMR
4