NEW P-CHIRAL POLYFLUOROALKYL PHOSPHORODIAMIDITE LIGAND
Scheme 3.
1847
Palladium-catalyzed allylic amination of 1,3-di-
phenylprop-2-en-1-yl acetate (I) with dipropyl-
amine. A solution of 3.7 mg (0.01 mmol) of
[Pd(π-All)Cl]2 and 7.04−14.08 mg (0.01−0.02 mmol)
of ligand L in 5 ml of THF or methylene chloride was
stirred for 10 min. Compound I, 0.1 ml (0.5 mmol),
was then added, the mixture was stirred for 15 min,
0.2 ml (1.5 mmol) of freshly distilled dipropylamine
was added, and the mixture was stirred for 48 h and
passed through a layer of silica gel. The solvent was
removed under reduced pressure (40 mm), and the
residue was kept for 1 h at a residual pressure of 1 mm.
The ee value was determined by HPLC (Daicel
Chiralcel OD-H; C6H14–i-PrOH–HNEt2, 1000:1:1,
0.5 ml/min; λ 254 nm) as described in [9].
O
O
Et2Zn, CuTC, L
Me
III
IV
tion of 1,3-diphenylprop-2-en-1-yl acetate [5, 6]. On
the other hand, ligand L was much more effective than
its analogs having a 3-phenyl-1,3-diaza-2-phosphabi-
cyclo[3.3.0]octane skeleton in Cu-catalyzed conjugate
addition of Et2Zn to cyclohex-2-en-1-one. The cor-
responding π*,N-bidentate phosphorodiamidites en-
sured enantiomeric excess of no higher than 55% [7],
while π*-monodentate, only ee 10–20% [8].
Copper-catalyzed conjugate addition of diethyl-
zinc to 2-cyclohexen-1-one (III). Ligand L,
0.04 mmol, was added at 20°C under argon to a solu-
tion of 0.02 mmol of copper thiophenecarboxylate in
2.5 ml of diethyl ether. The mixture was stirred for
30 min, cooled to –30°C, and kept for 30 min at that
temperature. A 1 M solution of diethylzinc in hexane,
2.4 mmol, was added, the mixture was stirred for
20 min, and a solution of 2 mmol of compound III in
0.5 ml of diethyl ether was added. The mixture was
stirred for 3 h, allowed to warm up to room tempera-
ture, diluted with 20 ml of diethyl ether, and extracted
with 2 N hydrochloric acid. The organic phase was
then washed with a concentrated solution of sodium
chloride, dried over sodium sulfate, and evaporated
under reduced pressure (40 mm). The residue was
purified by flash chromatography on silica gel using
cyclohexane–ethyl acetate (1:1) as eluent. The ee
value was determined by HPLC as described in [4].
(2S,5R)-2-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-
Nonadecafluorodecyloxy)-3-phenyl-1,3-diaza-2-
phosphabicyclo[3.3.0]octane (L). 2,2,3,3,4,4,5,5,6,6,-
7,7,8,8,9,9,10,10,10-Nonadecafluorodecan-1-ol, 0.785 g
(1.57 mmol), was added under vigorous stirring at
20°C to a solution of 0.378 g (1.57 mmol) of (2S,5R)-
2-chloro-3-phenyl-1,3-diaza-2-phosphabicyclo[3.3.0]-
octane and 0.22 ml (1.57 mmol) of triethylamine in
12 ml of THF. The resulting solution was stirred for
30 min at 20°C, heated to the boiling point, and kept
boiling for 2 h. It was then cooled to 20°C, the pre-
cipitate of triethylamine hydrochloride was filtered off,
the filtrate was evaporated under reduced pressure
(40 mm), and the residue was extracted with hexane
(3×15 ml). The extracts were combined, filtered, and
evaporated under reduced pressure (40 mm), and the
residue was evacuated for 2 h at a residual pressure of
1 mm. Yield 0.896 g (81%), light yellow oily sub-
stance which solidified on storage, mp 62–63°C.
All reactions were carried out under dry argon in
thoroughly dehydrated solvents. The 31P, 13C, and
19F NMR spectra were recorded on a Bruker Avance-
400 spectrometer at 161.98, 100.61, and 282.4 MHz,
respectively, using 85% H3PO4 in D2O, CDCl3
(δC 76.91 ppm), and CCl3F as references. Signals in
the 13C NMR spectrum of ligand L were assigned
using DEPT pulse sequence. The mass spectrum was
obtained on a Varian MAT-311 spectrometer. Elemen-
tal analysis was performed at the Organic Microanal-
ysis Laboratory, Nesmeyanov Institute of Organome-
tallic Compounds, Russian Academy of Sciences.
13C NMR spectrum (CDCl3), δC, ppm: 145.1 d (Carom
,
2J = 16.8 Hz), 129.2 s (CHarom), 119.7 s (CHarom),
3
115.0 d (CHarom, J = 11.7 Hz), 109.4 br.m (C2′–C10′),
63.2 d (C5, J = 8.8 Hz), 58.6 m (OCH2, 2J = 5.3 Hz),
2
2
2
54.9 d (C4, J = 6.6 Hz), 48.3 d (C8, J = 37.2 Hz),
31.8 s (C6), 26.4 d (C7, J = 3.7 Hz). 31P NMR spec-
3
trum (CDCl3): δP 124.1 ppm. 19F NMR spectrum
(CDCl3), δF, ppm: –79.1 to –79.35 m (3F), –117.92 s
(2F), –120.25 s (8F), –121.15 s (2F), –121.4 s (2F),
–124.55 s (2F). Mass spectrum (electron impact,
70 eV), m/z (Irel, %): 704 [M]+ (3), 484 [C10H2F19 + H]+
(8), 222 [M – C10H2F19 + H]+ (100), 205 [M –
C10H2F19O]+ (82). Found, %: C 36.04; H 2.37; N 3.79.
C21H16F19N2OP. Calculated, %: C 35.81; H 2.29;
N 3.98.
This study was performed under financial support
by the INTAS Foundation (project no. 05-1000008-
8064) and by the Russian Foundation for Basic Re-
search (project no. 04-03-39017-GFEN).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 12 2008
Benetskii
