Addition reactions of tertiary silylphosphanes with acetylenic ketones and aldehydes

Article abstract of DOI:10.1055/s-2002-33533

(Trimethylsilyl)phosphanes Me₃Si-PR₂ (PR₂ = PPH₂, PEt₂, 1-phospholanyl) add smoothly across the C≡C bond of acetylenic ketones RCOC≡CPh to form (Z)-3-phosphanyl-2-(trimethylsilyl)prop-2-en-1-ones 3 (3, 4-addition). Thermal isomerization of the latter yields the corresponding 3-(trimethylsilyl)oxy-allenylphosphane 6, formally the product of a 1, 4-addition. Mainly 1, 2-addition occurs with propiolic aldehydes leading to (1-[(trimethylsilyl)oxy]propargyl)phosphanes 4. Desilylation reactions of 3b yield either (3-oxopropyl)phosphanoxide 7 or (3-oxopropenyl)phosphanoxide 8.

Full text of DOI:10.1055/s-2002-33533

LETTER
1459
Addition Reactions of Tertiary Silylphosphanes with Acetylenic Ketones and
Aldehydes
Addition Reactions of
a
T
ertiary Sil
r
ylphosph
t
anes in Reisser, Alexandra Maier, Gerhard Maas*
Abteilung Organische Chemie I, Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
Fax +49(731)5022803; E-mail: gerhard.maas@chemie.uni-ulm.de
Received 18 June 2002
PR1
2
Abstract: (Trimethylsilyl)phosphanes Me3Si–PR2 (PR2 = PPh2,
PEt2, 1-phospholanyl) add smoothly across the C C bond of acetyl-
enic ketones RCOC CPh to form (Z)-3-phosphanyl-2-(trimethyl-
silyl)prop-2-en-1-ones 3 (3,4-addition). Thermal isomerization of
the latter yields the corresponding 3-(trimethylsilyl)oxy-alle-
nylphosphane 6, formally the product of a 1,4-addition. Mainly 1,2-
addition occurs with propiolic aldehydes leading to (1-[(trimethyl-
silyl)oxy]propargyl)phosphanes 4. Desilylation reactions of 3b
yield either (3-oxopropyl)phosphanoxide 7 or (3-oxopropen-
yl)phosphanoxide 8.
Me3Si
Me3Si
1c
P
1a: R1 = Ph
1b: R1 = Et
O
O
Ph
PR1
1a−c
R2
Ph
R2
Me3Si
2
69-75%
2
3
Key words: organophosphorus(III) compounds, organosilicon
compounds, nucleophilic addition at alkynones, enones, siloxy-
allenes
3
a
b
c
d
e
PR1
PPh2
PEt2
Ph
PPh2
PEt2
Me
P
2
R2
Ph
Ph
Tertiary silylphosphanes react with , -unsaturated ole-
finic ketones and aldehydes in general by addition across
the C=C double bond (3,4-addition).1 Surprisingly, analo-
gous reactions with acetylenic carbonyl compounds are
barely known: Märkl et al. have reported the synthesis of
a 4-phosphacyclohexadien-1-one from 1,5-diphenyl-1,4-
pentadiyn-3-one and PhP(SiMe3)2 in the presence of
AIBN,2 and Regitz et al. have described the insertion of
acetylenic esters and ketones into the P–Si bond of P-
silylated cyclopropenylidenephosphanes3 and 1,2-dihy-
dro-1,2-phosphasiletes.4 We report now that more com-
mon and readily accessible dialkyl- and diaryl(tri-
methylsilyl)phosphanes also react smoothly with acety-
lenic carbonyl compounds and that the formation of 3,4-,
1,2-, and 1,4-addition products is feasible. Reactions of
diphenyl(trimethylsilyl)phosphane with terminal and in-
ternal alkoxyalkynes have been investigated recently by
Russian researchers.5
Silylphosphanes 1a–c6 reacted readily with acetylenic ke-
tones 2a–c in a 3,4-addition mode to furnish 3-phospha-
nyl-2-(trimethylsilyl)propenones 3a–e in good yield
(Scheme 1).7 Acetonitrile or THF was used as the solvent
since related phosphane additions to olefinic substrates
were found to be faster in polar solvents.1 Acetonitrile had
the additional advantage that some of the products crystal-
lized directly from the reaction solution.
S
Scheme 1 Conditions: CH3CN or THF, 0 20 °C
the C=C-C=O unit was recognized by the 13C chemical
shifts together with characteristic P,C coupling constants.
The 29Si NMR signal of 3b was observed as a doublet at
= –8.5 ppm [3J(Si,P) = 11.4 Hz]. These data exclude the
alternative structures of 1,2- and 1,4-addition products
featuring Me3SiO functionalities (vide infra). It is reason-
able to assume that the formation of 3 begins with an ad-
dition of the nucleophilic phosphorus atom of
silylphosphanes 1 at the electron-deficient triple bond of
acetylenic ketones 2. The NMR spectra showed the pres-
ence of only one isomer in all cases. The magnitudes of
3
4
the J(P,C=O) (19.5–24.2 Hz), J(P,SiC) (9.5–10.2 Hz),
and 5J(P,SiCH3) (1.2–1.6 Hz, except for 3d) coupling con-
stants indicate the same double bond configuration in all
cases. However, a definite assignment cannot be made be-
cause a rigorous stereochemical proof for related systems4
is not available and it has been noted that no obvious ste-
reochemical dependence of the 3J(P,C) coupling constant
in vinylphosphanes exists.8 An X-ray crystal structure
analysis of 3b provided the definite proof of the Z config-
uration (Figure).9 The H and 13C NMR spectra of 3b
1
show temperature-dependent signals and coalescence
phenomena for the PEt2 group and the adjacent phenyl
ring. This is probably due to steric hindrance between
the SiMe3 and the PEt2 groups which slows down the
exchange between the position of the PEt2 group (see
Figure) and a conformation obtained by a 180° rotation
around the C(sp2)–P bond.
The identity of enones 3a–e was established by their spec-
troscopic data (Table). A strong IR absorption at 1629–
1687 cm–1 indicated the presence of a carbonyl group, and
Synlett 2002, No. 9, Print: 02 09 2002.
Art Id.1437-2096,E;2002,0,09,1459,1462,ftx,en;G16702ST.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0936-5214

1460
M. Reisser et al.
LETTER
Table Selected IR, 13C{1H} NMR, and 31P NMR Data of Compounds 3, 4, and 6
Com-
pound
IR [cm–1]
(C=O)
13C NMR (125.77 MHz, CDCl3, TMS), [ppm] (JC,P [Hz])
31P NMR,
[ppm]
C-1
C-2
C-3
Other Signals
3a
1663
1655
200.6 (23.9)
200.5 (20.4)
151.5 (25.2)
154.3 (26.7)
164.8 (52.8)
164.0 (49.1)
0.9 (d, 4JC,P = 10.0, SiMe3), 126.0–139.0 (CPh)
2.2
3ba
1.8 (d, 4JC,P = 10.1, SiMe3), 10.4 (d, 2JC,P
=
–17.8
16.2, CH3), 11.1 (d, 2JC,P = 16.0, CH3), 18.4
(d, 1JC,P = 10.0, PCH2), 18.5 (d, 1JC,P = 9.4,
PCH2), 125.9–137.2 (CPh)
3c
3d
3e
1650
1629
1687
200.8 (19.5)
192.5 (24.2)
208.6 (20.2)
156.6 (34.0)
152.3 (25.6)
151.1 (26.7)
159.5 (47.4)
164.1 (55.2)
166.4 (48.0)
1.4 (d, 4JC,P = 10.0, SiMe3), 25.8 (m, br,
PCH2), 28.2 (s, 2 C, CH2), 126.0–139.3 (CPh)
–18.2
2.6
1.4 (d, 4JC,P = 9.5, SiMe3), 126.1–144.3 (CPh,
CThie
)
1.7 (d, 4JC,P = 10.2, SiMe3), 10.4 (d, 2JC,P
=
–17.2
17.1, CH3), 18.8 (d, 1JC,P = 11.2, PCH2), 31.4
(d, 4JC,P = 2.3, CH3CO), 126.5, 127.6, 127.7,
137.6
4a
4b
6
–
–
–
64.4 (–)
88.2, 88.5
87.2, 87.8
4.2
61.9 (11.4)
118.3 (23.9)
–16.0
201.0
0.2 (s, SiMe3), 9.65 (d, 2JC,P = 10.1, CH3), 9.87 –10.6
(d, 2JC,P = 16.3, CH3), 17.4 (d, 1JC,P = 10.1,
PCH2), 17.8 (d, 1JC,P = 13.8, PCH2), 124.4–
137.3
a The 13C NMR spectrum was recorded at 233 K.
When silylphosphanes 1a,b were combined with phenyl-
propargyl aldehyde, the nucleophilic 1,2-addition at the
aldehyde function dominated by far over the 3,4-addition,
and propargylphosphanes 4, accompanied by traces of
acrylic aldehyde derivatives 5, were obtained10
(Scheme 2).
O
1a,b
Ph
H
O
OSiMe3
PR2
Ph
PR1
H
+
The direct 1,4-addition of silylphosphanes 1 at the conju-
gated system of alkynones 2, leading to 1-phosphanyl-3-
siloxyallenes, was not observed in any of the reactions de-
Me3Si
Ph
2
4
5
Scheme 2 Conditions: CH3CN or THF, 0 20 °C
scribed above. However, when enone 3b was heated in
toluene at 150 °C in toluene in a closed thick-walled
Schlenk tube, thermal rearrangement into allene 6 took
place through a 1,3(C O) SiMe3 shift (Scheme 3). The
isomerization was almost complete after 40 h; at this
stage, the 31P NMR spectrum showed the signals of 6 and
3b in a ratio of 99.4:0.6, accompanied by ca 2% of a signal
at = 47.7 ppm (POEt2).11 The formation of 6 is in accord
with the NMR data (Table) which show the disappearance
of the olefinic carbon signals of the enone while the sin-
glet signal of the central allenic carbon ( = 201.0 ppm)
replaces the doublet signal of the carbonyl carbon of 3b
( = 200.5 ppm). Also indicative of the formation of the
trimethylsilyloxy function is the small high-field shift of
the 1H and 13C signals of the SiMe3 group both of which
no longer show a long-range coupling with the P nucleus.
Figure Molecular structure of 3b in the solid state (ORTEP plot);
the ellipsoids of thermal vibration represent a 50% probability
Synlett 2002, No. 9, 1459–1462 ISSN 0936-5214 © Thieme Stuttgart · New York

LETTER
Addition Reactions of Tertiary Silylphosphanes
1461
References
O
toluene,
150 °C, 40 h
Me3SiO
Ph
Ph
PEt2
Ph
PEt2
(1) Couret, C.; Escudié, J.; Satgé, J.; Anh, N. T.; Soussan, G. J.
Organomet. Chem. 1975, 91, 11.
Ph
Me3Si
(2) Märkl, G.; Olbrich, H. Tetrahedron Lett. 1968, 35, 3813.
(3) (a) Fuchs, E. P. O.; Heydt, H.; Regitz, M.; Schoeller, W. W.;
Busch, T. Tetrahedron Lett. 1989, 30, 5111. (b) Fuchs, E. P.
O.; Breit, B.; Bergsträsser, U.; Hoffmann, J.; Heydt, H.;
Regitz, M. Synthesis 1991, 1099.
6
3b
Scheme 3
Due to the presence of different functional groups, com-
pounds 3 should be amenable to various further transfor-
mations. In an effort to remove the SiMe3 group, we found
that treatment of 3b with acids gave the (3-oxoprop-
yl)phosphanoxide 712 formally resulting from desilylation
and addition of water (Scheme 4). This trans-formation
represents a novel method to prepare compounds of type
7.13 Protodesilylation with conservation of the olefinic
bond was achieved when 3b was kept in wet acetone; not
unexpectedly, concomitant oxidation of the phosphanyl
function also took place. The resulting (3-oxoprope-
nyl)phosphanoxide 8 was obtained as a E,Z mixture which
could be separated by column chromato-graphy.14 The
stereochemical assignment can be based reliably on 3JP,H
and 3JP,C coupling constants (trans > cis).8
(4) (a) Haber, S.; Boese, R.; Regitz, M. Angew. Chem., Int. Ed.
Engl. 1990, 29, 1436; Angew. Chem. 1990, 102, 1523.
(b) Haber, S.; Schmitz, M.; Bergsträsser, U.; Hoffmann, J.;
Regitz, M. Chem.–Eur. J. 1999, 5, 1581.
(5) Kochetkov, A. N.; Efimova, I. V.; Trostyanskaya, I. G.;
Kazankova, M. A.; Beletskaya, I. P. Russ. Chem. Bull. 1998,
47, 1744.
(6) (a) 1a: Appel, R.; Geisler, K. J. Organomet. Chem. 1976,
112, 61. (b) 1b: Fritz, G.; Poppenburg, G. Angew. Chem.
1960, 72, 208. (c) Fritz, G.; Poppenburg, G.; Rocholl, M. G.
Naturwissenschaften 1962, 74, 255. (d) 1c Was obtained
analogously form 1-phenyl- or 1H-phospholane.
(7) (Z)-3-(Diphenylphosphanyl)-1,3-diphenyl-2-(trimethyl-
silyl)prop-2-en-1-one(3a); general procedure: A solution of
1,3-diphenylprop-2-yn-1-one (2a, 3.1 g, 15.0 mmol) in THF
(100 mL) was cooled at 0 °C and diphenyl(trimethyl-
silyl)phosphane (1a, 3.87 g, 15.0 mmol) was added. The
reaction mixture was kept with stirring at 0 °C for 2 h, then
at 20 °C for 12 h. The solvent was evaporated at 15 mbar and
the solid residue was recrystallized from CH3CN to furnish
3a as colorless crystals (5.22 g, 75%), mp 127–128 °C. IR
(KBr): 1663 s, 1243 s, 1233 s, 858 s, 842 s cm–1. 1H NMR
(CDCl3, 500.14 MHz): = 0.51 (d, 5JH,P = 1.2 Hz, 9 H,
SiMe3), 6.3–7.8 (20 HPh). MS (EI, 70 eV): m/z (%) = 466 (9),
465 (33), 464 (100) [all M+].
O
O
Ph
Ph
PEt2
a
Ph
Ph
PEt2
O
Me3Si
3b
7
b
3b: From 1b and 2a; large pale-yellow crystals, 69% yield,
mp 100 °C. IR (KBr): 1655 s, 1237 s, 844 s, 703 m cm–1.
Ph
POEt2
1H NMR (CDCl3, 500.14 MHz, 233 K): = 0.35 (d, 5JH,P
=
PhCO
H
Ph
POEt2
+
1.6 Hz, 9 H, SiMe3), 1.0–1.4 (m, 10 Hethyl), 6.6–7.6 (10 HPh).
29Si NMR (CDCl3, 99.37 MHz): = –8.5 (d, 3JSi,P = 11.4 Hz).
MS (EI, 70 eV): m/z (%) = 370 (5), 369 (10), 368 (39) [all
M+], 279 (100). C22H29OSiP (368.53): calcd C 71.70, H 7.93;
found C 71.38, H 8.12.
3c: From 1c and 2a; pale-yellow crystals, 69% yield, mp 99
°C. IR (KBr): 1667/1650 vs, 1230 vs, 1174 vs, 702 vs
cm–1. 1H NMR (CDCl3, 500.14 MHz): = 0.35 (d, 5JH,P = 1.5
Hz, 9 H, SiMe3), 1.08–1.25 (m, coalescing, 2 H), 1.35–1.45
(m, 2 H), 1.65–1.90 (m, 4 H), 6.7–7.7 (10 HPh). MS (EI, 70
eV): m/z (%) = 368 (2), 367 (7), 366 (25) [all M+], 279 (100).
C22H27OPSi (366.51): calcd C 72.10, H 7.42; found C 71.80,
H 7.55.
3d: From 1a and 2b; 70% yield, amorphous solid, mp 149
°C. IR (KBr): 1629 vs, 1413 s, 1261 s, 1246 s, 846 vs, 743
vs, 725 s, 702 vs cm–1. 1H NMR (CDCl3, 500.14 MHz):
= 0.44 (s, 9 H, SiMe3), 6.4–7.5 (18 Harom). MS (EI, 70 eV):
m/z (%) = 472 (13), 471 (36), 470 (100) [all M+], 469 (39).
C28H27OPSSi (470.64): calcd C 71.46, H 5.78; found C
71.52, H 5.62.
3e: From 1b and 2c, malodorous colorless oil, isolated by
bulb-to-bulb distillation at 80–100 °C/0.0001 mbar; 76%
yield. IR (KBr): 1687 s, 1245 s, 1187 s, 841 s cm–1. 1H NMR
(CDCl3, 500.14 MHz): = 0.49 (d, 5JH,P = 1.5 Hz, 9 H,
SiMe3), 1.19 (dt, 6 H, CH2CH3), 1.35 (m, 4 H, PCH2), 1.86
(d, 5JH,P = 1.4 Hz, COCH3), 6.90–7.00 (m, 2 HPh), 7.32–7.43
(m, 3 HPh). MS (EI, 70 eV): m/z (%) = 308 (2), 307 (9), 306
(43) [all M+], 217 (100). C17H27OPSi (306.46): calcd C
66.63, H 8.88; found C 67.31, H 8.25.
H
PhCO
E-8
Z-8
Scheme 4 a) CF3COOH, CHCl3, 24 h, 59% yield; b) wet acetone,
r.t., 3–5 days, yield: 38% E-8, 21% Z-8 (ca. 10% of residual 3b).
In conclusion, we have shown that tertiary trimethylsilyl-
phosphanes add smoothly in a syn fashion to the triple
bond of acetylenic ketones, and we have furnished an un-
equivocal proof for the Z configuration of the products 3.
In contrast, the reaction of Me3Si–PPh2 with internal
alkoxyalkynes requires much more forcing conditions and
was reported to give anti-addition products.5 The presence
of several different functional groups in compounds 3,
which are , -unsaturated phosphanes, silanes, and carb-
onyl compounds simultaneously, provides opportunities
for various synthetic transformations. First examples
are given here by their thermal isomerization leading to
siloxyallenes 6 and desilylation reactions leading to phos-
phanoxides 7 or 8.
Acknowledgement
We are grateful to the Fonds der Chemischen Industrie for financial
support.
(8) Duncan, M.; Callagher, M. J. Org. Magn. Reson. 1981, 15,
37.
Synlett 2002, No. 9, 1459–1462 ISSN 0936-5214 © Thieme Stuttgart · New York

1462
M. Reisser et al.
LETTER
MHz): = 1.01 (dt, 3JP,H = 17.0 Hz, 3JH,H = 7.7 Hz, 3 H,
(9) Crystal data for 3b: Triclinic, space group P1, a = 9.432
(3), b = 9.611 (2), c = 12.548 (3) Å, = 98.82 (3),
=
CH2CH3), 1.23 (dt, 3JP,H = 17.2 Hz, 3JH,H = 7.7 Hz, 3 H,
CH2CH3), 1.49–1.74 (m, 2 H, PCH2), 1.84–2.05 (m, 2 H,
PCH2), 3.80 (mc, 2 H, COCH2), 3.95 (mc, 1 H, PCH), 7.26–
7.55 (m, 8 Harom), 7.96 (dd, 2 Harom). 13C{1H} NMR (CDCl3,
100.61 MHz): = 5.88/5.92 (2 d, JP,C = 44.3/44.3 Hz,
PCH2CH3), 18.51/19.25 (2 overlapping d, PCH2), 38.6 (s,
COCH2), 39.1 (d, JP,C = 61.4 Hz, CHPOEt2), 127.2–137.5
(CPh), 196.9 (d, JP,C = 10.2 Hz, CO). 31P (CDCl3): = 54.8.
C19H23O2P (314.36): calcd C 72.59, H 7.37; found C 72.82,
H 7.51.
102.21 (3), = 101.69 (3); Z = 2, Dcalc = 1.149 g·cm–3.
Crystallographic data have been deposited at the Cambridge
Crystallographic Data Centre as supplementary publication
no. CCDC-187712. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or
from the Cambridge Crystallographic Data Centre, 12,
Union Road, Cambridge CB2 1EZ, UK; fax:
+44(1223)336033).
(10) Yield of crude 4a,b: ~90%; since both compounds are
extremely malodorous oils, we refrained from further
purification. Data for 4a: 1H NMR (CDCl3, 500.14 MHz):
= 0.17 (s, SiMe3), 5.33 (d, 2JH,P = 1.2 Hz, HCC C), 7.23–
7.70 (m, 5 HPh). 13C{1H} NMR (CDCl3, 50.32 MHz): = 0.2
(s, SiMe3), 64.4 (s, HCC C), 88.21 (d, JC,P = 10.6 Hz) and
88.63 (d, JC,P = 5.0 Hz) (C C). This product was isolated as
(13) For other methods to prepare -ketophosphinates and
-phosphanoxides, see: (a) Bell, A.; Davidson, A. H.;
Earnshaw, C.; Norrish, H. K.; Torr, R. S.; Trowbridge, D. B.;
Warren, S. J. Chem. Soc., Perkin Trans. 1 1983, 2879.
(b) Pudovik, A. N.; Sovanov, A. A.; Bakhtiyarova, I. V.;
Zimin, M. G. Zh. Obshch. Khim. 1983, 53, 2456.
(14) (Z)-8: Colorless oil. IR(film): 1669 (s, C=O), 1225 (s), 1174
(s, P=O) cm–1. 1H NMR (CDCl3, 400.13 MHz): = 1.14 (dt,
3JP,H = 17.4 Hz, 3JH,H = 7.7 Hz, 6 H, PCH2CH3), 1.80–1.97
(m, 4 H, POCH2), 7.24 (d, 3JP,H = 30.5 Hz, 1 H, COCH=),
7.35–7.60 (3 m, 8 Harom), 7.97–8.00 (dd, 2 Harom). 13C{1H}
NMR (CDCl3, 100.61 MHz): = 5.67 (d, JP,C = 5.3 Hz,
PCH2CH3), 21.9 (d, JP,C = 69.1 Hz, PCH2), 128.1–128.8
(several C), 133.8 (CH), 137.0, 138.8 (d, JP,C = 9.1 Hz),
a 6.2:1 mixture (31P NMR) with 5a [ (1H) = 0.43 (d, 5JH,P
=
1.5, SiMe3); (13C) = 1.8 (d, 4JC,P = 9.1, SiMe3), 198.0 (3JC,P
= 17.4, CHO); (31P) = 3.4].
Data for 4b: IR (film): 1679 m, 1599 m, 1251 vs, 1065 vs,
868 vs, 844 vs, 754 m cm–1. 1H NMR (CDCl3, 200.13 MHz):
= 0.16 (s, 9 H, SiMe3), 0.90–1.15 (dt, 6 H, CH2CH3), 1.30–
1.70 (m, 4 H, PCH2), 4.78 (d, JH,P = 5.0 Hz, HCC C), 7.15–
7.40 (m, 5 HPh). 13C{1H} NMR (CDCl3, 50.32 MHz):
=
0.09 (s, SiMe3), 9.85 and 9.95 (each d, JC,P = 15.1 Hz,
142.3 (JP,C = 5.4 Hz, COCH=), 145.8, 146.5, 192.9 (d, JP,C
4.9 Hz, C=O). 31P: = 46.4. C19H21O2P (312.35): calcd C
73.06, H 6.78; found C 72.68, H 6.94. (E)-8: Colorless
=
CH2CH3), 16.4 (d, JC,P = 15.1 Hz, PCH2), 16.7 (d, JC,P = 14.1
Hz, PCH2), 61.9 (d, JC,P = 11.6 Hz, HCC C), 87.2 (s) and
87.9 (d, JC,P = 4.0 Hz) (C C). This product was isolated as a
94:6 mixture (31P NMR) with 5b [ (1H) = 0.32 (d, 5JH,P = 1.6
Hz, SiMe3); (13C) = 2.3 (d, 4JC,P = 10.7 Hz, SiMe3)].
(11) Allene 6 was obtained as an oil (~97% purity by 31P NMR)
which could not be purified further by chromatography or
vacuum distillation without decomposition. 1H NMR
(CDCl3, 500.14 MHz): = 0.21 (s, 9 H, SiMe3), 1.04 and
1.42 (each dt, 3 H, PCH2CH3), 1.58–1.74 (m, 4 H, PCH2),
7.24–7.38 (m, 6 HPh), 7.61 (dd, 2 HPh), 7.64 (dd, 2HPh).
(12) 7: colorless crystals, mp 89 °C. IR (KBr): 1688 (s, C=O),
1266 m, 1158 (s, P=O) cm–1. 1H NMR (CDCl3, 400.13
crystals, mp 80 °C. IR (solid, ATR): 1659 (s, C=O), 1254 (s),
1188 (s, P=O) cm–1. 1H NMR (CDCl3, 400.13 MHz):
=
1.25 (dt, 3JP,H = 16.9 Hz, 3JH,H = 7.6 Hz, 6 H, PCH2CH3),
1.67–1.86 (m, 4 H, POCH2), 7.09–7.52 (4 m, 8 Harom), 7.82
(d, 3JP,H = 17.8 Hz, 1 H, COCH=), 7.87 (dd, 2 Harom).
13C{1H} NMR (CDCl3, 100.61 MHz): = 5.42 (d, JP,C = 5.7
Hz, PCH2CH3), 19.6 (d, JP,C = 69.8 Hz, PCH2), 127.6–128.9
(several C), 133.5 (CH), 134.9 (d, JP,C = 9.1 Hz), 136.6,
140.3 (JP,C = 5.7 Hz, COCH=), 145.8, 146.5, 191.9 (d, JP,C
=
14.8 Hz, C=O). 31P: = 44.2. C19H21O2P (312.35): calcd C
73.06, H 6.78; found C 73.11, H 6.83.
Synlett 2002, No. 9, 1459–1462 ISSN 0936-5214 © Thieme Stuttgart · New York