Reactions of N-PIII-Phosphorylated trifluoroacetamides with (ethoxycarbonyl)triphenylmethylide

Article abstract of DOI:10.1007/s11176-005-0430-8

N-P^III-Phosphorylated trihaloacetamides act as phosphorylating agents with respect to (ethoxycarbonyl) triphenylmethylide. The reactions give rise to C-phosphorylated ylides and O-(diethoxyphosphino)-phosphaketene acetals. 2005 Pleiades Publish

Full text of DOI:10.1007/s11176-005-0430-8

Russian Journal of General Chemistry, Vol. 75, No. 9, 2005, pp. 1373 1375. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 9, 2005,
pp. 1445 1447.
Original Russian Text Copyright
2005 by Shalimov, Malenko, Repina, Sinitsa.
Reactions of N PIII-Phosphorylated Trifluoroacetamides
with (Ethoxycarbonyl)triphenylmethylide
A. A. Shalimov, D. M. Malenko, L. A. Repina, and A. D. Sinitsa
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received July 15, 2004
Abstract N PIII-Phosphorylated trihaloacetamides act as phosphorylating agents with respect to (ethoxy-
carbonyl)triphenylmethylide. The reactions give rise to C-phosphorylated ylides and O-(diethoxyphosphino)-
phosphaketene acetals.
Our synthesized N PIII-phosphorylated N-alkyltri-
fluoroacetamides I are ambident electrophilic re-
agents, and in reactions with nucleophiles they can
act both as phosphorylating and trifluoroacetylating
agents.
the electron-acceptor phosphino group at the nitro-
gen atom would exhibit enhanced reactivity not
only toward activated, but also toward stabilized
ylides.
In view of the aforesaid and with the aim to study
the properties of N PIII-phosphorylated trihaloacet-
amides, we have studied reactions of N-alkyl- and
N-phenyl-N-phosphinotrifluoroacetamides with
(ethoxycarbonyl)triphenylmethylide (II).
It is known that trifluoroacetamides and activated
ylides enter the Wittig reaction to form enamines [2]
and their subsequent cyclization products [3]. It might
be expected that N-alkyl(aryl)trifluoroacetamides with
X = Cl (a), Ph (b)
Ph3P=C COOEt
PX2
CF3CON(R)PX2 + Ph3P=CHCOOEt
IIIa, IIIb
CF3CONHR
Ia If
II
(EtO)2P
Ph3P=C=C
IV
O
X = OEt
OEt
I, R = Me, X = Cl (a), Ph (b), OEt (c); R = Bu, X = Cl (d), Ph (e), OEt (f). III, X = Cl (a), Ph (b).
It was found that amidophosphines Ia, Ib, Id, and
Ie react with ylide II to form C-phosphinylides IIIa
and IIIb, i.e. nucleophilic substitution at PIII takes
place. An interesting feature of this reaction is the
substitution of the amido group rather than chlorine in
dichlorophosphinamide Ia (X = Cl). The structure of
ylides IIIa and IIIb was proved by spectral data, as
well as the identity of one of them (compound IIIb)
to that obtained from chlorodiphenylphosphine with
excess ylide II as HCl acceptor [4]. Attempted substi-
tution of the chlorine atom in ylide IIIa under the
action of amines results in C PIII bond cleavage.
stantial effect on the direction and facility of the reac-
tions, unlike the nucleophilicty of the ylides. Thus,
amidophosphines I fail to react with benzoyl(triphenyl-
phosphino)methylide that is less nucleophilic than its
alkoxycarbonyl analog II. The reactions of ylide II
with diethyl trifluoroacetylphoshoramidites Ic and If
take an unusual pathway to form heterocumulene IV.
The IR spectrum of the latter display a band at
1
2225 cm , characteristic of the P=C=C triad [5]. The
31P NMR spectrum of heterocumulene IV shows sig-
nals at 18.2 and 180.4 ppm (4JPP 9.2 Hz). Evidence
for the presence in compound IV of sp- and sp2-
carbon atoms is provided by the 13C NMR spectra
(see Experimental) that are consistent with the spectra
Substituents R in amidophosphines I have no sub-
1070-3632/05/7509-1373 2005 Pleiades Publishing, Inc.

1374
SHALIMOV et al.
1
of ethoxyphosphaketene acetals [6]. Compound IV is
a representative of previously unknown O PIII-phos-
phorylated phosphaketene acetals [7].
Hg). IR spectrum (thin film), , cm : 1720 (C=O).
19F NMR spectrum (C6D6), F, ppm: 65.8 d (4JFP
77.8 Hz). 31P NMR spectrum (C6D6), P, ppm: 60.7 q
(4JFP 77.8 Hz). Found P, %: 8.81. C18H19F3NOP.
Calculated P, %: 8.77.
IV + HX
II + (EtO)2PX,
V
N-Butyl-N-(diethoxyphosphino)trifluoroacet-
amide (If). Yield 48%, bp 86 90 C (0.08 mm Hg),
X = OH, AlkO, Alk2N.
n1D5 1.5372. IR spectrum (thin film), , cm : 1740
1
Ketene acetal IV readily reacts with water, alcohols,
amines, and other compounds containing active
hydrogen. The reactions provide ylide II and cor-
responding phosphorus acid derivatives V.
(C=O). 19F NMR spectrum (C6D6), F, ppm: 66.7 d
(4JFP 93.7 Hz). 31P NMR spectrum (C6D6), P, ppm:
146.2 q (4JFP 93.7 Hz). Found P, %: 10.38. C10H19
F3NO3P. Calculated P, %: 10.71.
Ethyl (dichlorophosphino)(triphenylphosphor-
anylidene)acetate (IIIa). To a solution of 0.004 mol
of N-methyl- (Ia) or N-butyl-N-(dichlorophosphino)-
trifluoroacetamide (Id) in 10 ml of ether, a suspension
of 0.004 mol of (ethoxycarbonylmethylene)triphenyl-
phosphorane (II) in 10 ml of ether. The mixture was
left overnight. The precipitate was filtered off, and
the residue was kept for 8 h at 40 50 C (0.08 mm
Hg). Yield 75 79% (dark red oil). IR spectrum (thin
film), , cm : 1650 1710, 1900, 1960. H NMR
spectrum (C6D6), , ppm: 0.79 t (3H, CH3), 3.75 q
(2H, CH2), 7.07 7.19 m (9H, Harom); 7.52 7.62 m
(6H, Harom). 13C NMR spectrum (C6D6), C, ppm:
EXPERIMENTAL
The IR spectra were registered on a UR-20 spec-
1
trophotometer. The H, 13C, and 31P NMR spectra
were obtained on a Varian VXR-300 spectrometer at
299.15, 75.43, and 121.42 MHz, respectively, against
internal HMDS (1H, 13C) and external 85% H3PO4
(31P). All manipulations were carried out under dry
argon.
1
1
N-(Dichlorophosphino)-N-methyltrifluoroacetamide
(Ia) was prepared as described in [1].
N PIII-Phosphorylated N-alkyltrifluoroacet-
amides Ib, Id, Ie, and If (general procedure). To a
solution of 0.1 mol of N-alkyltrifluoroacetamide and
0.1 mol of triethylamine in 180 ml of ether, 0.1 mol
of P(III) chloride was added dropwise with vigorous
stirring over the course of 2 h so that the temperature
of the reaction mixture was maintained below 10 C.
The mixture was left overnight, and the triethylamine
hydrochloride was filtered off and washed with ether
(2 20 ml). The solvent was removed, and the reac-
tion products were isolated by vacuum distillation or
crystallization.
IV
III
14.24 s (CH3), 33.76 d.d (PCP, JCP 93.6 Hz, JCP
IV
25.2 Hz), 59.50 s (CH2), 125.32 d.d (Cipso, JCP
III
92.9 Hz, JCP 5.4 Hz), 129.00 s (Cp2), 129.33 d (Cm,
3JCP 12.3 Hz), 129.42 d (Co, JCP 13.4 Hz),
2
2
IV
III
167.33 d.d (C=O, JCP 13.0 Hz, JCP 9.1 Hz).
31P NMR spectrum (C6D6), P, ppm: 21.9 d (Ph3P,
2JPP 185.5 Hz), 166.3 d (PCl2, 2JPP 185.5 Hz). Found
P, %: 13.24. C22H20Cl2O2P2. Calculated P, %: 13.79.
Ethyl (diphenylphosphino)(triphenylphosphor-
anylidene)acetate (IIIb). To a solution of 0.004 mol
of N-methyl- (Ia) or N-butyl-N-(dichlorophosphino)-
trifluoroacetamide (Id) in 5 ml of benzene, a suspen-
sion of 0.004 mol of (ethoxycarbonylmethylene)tri-
phenylphosphorane (II) in 5 ml of benzene. The mix-
ture was kept at 30 35 C for 4 h and left overnight.
The solvent was removed, and the residue was washed
with 20 ml of ether. Yield 71 74%, mp 151 152 C.
N-(Diphenylphosphino)-N-methyltrifluoroacet-
amide (Ib). Yield 38%, mp 76 79 C (benzene
1
hexane, 1:2). IR spectrum (Nujol), , cm : 1700
(C=O). 19F NMR spectrum (C6D6), F, ppm: 65.2 d
(4JFP 75.8 Hz). 31P NMR spectrum (C6D6), P, ppm:
60.1 q (4JFP 75.8 Hz). Found P, %: 10.42. C15H13F3
NOP. Calculated P, %: 9.95.
31P NMR spectrum (C6D6), P, ppm: 28.7 d (Ph3P,
2JPP 183.5 Hz), 14.1 d (Ph2P, 2JPP 183.5 Hz), which
N-Butyl-N-(dichlorophosphino)trifluoroacet-
amide (Id). Yield 50%, bp 43 45 C (0.08 mm Hg),
n1D5 1.3842. IR spectrum (CCl4), , cm : 1750 (C=O).
corresponds to published data [4].
1
Diethyl 1-ethoxy-2-(triphenylphosphoranyl-
idene)vinyl phosphite (IV). To a solution of
0.0074 mol of N-methyl- (Ic) or N-butyl-N-(diethoxy-
phosphino)trifluoroacetamide (If) in 10 ml of benzene,
a suspension of 0.0074 mol of (ethoxycarbonylme-
thylene)triphenylphosphorane (II) in 20 ml of benzene
was added with stirring. The mixture was kept for 1 h
19F NMR spectrum (C6D6), F, ppm: 68.5 d (4JFP
100.9 Hz). 31P NMR spectrum (C6D6), P, ppm:
169.8 q (4JFP 100.9 Hz). Found P, %: 11.39. C6H9
Cl2F3NOP. Calculated P, %: 11.47.
N-Butyl-N-(diphenylphosphino)trifluoroacet-
amide (Ie). Yield 35% (oil), bp 142 146 C (0.07 mm
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 9 2005

REACTIONS OF N PIII-PHOSPHORYLATED TRIFLUOROACETAMIDES
at 50 60 C. The solvent was removed in a vacuum,
1375
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1
1
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2
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 9 2005