New stannyl enamides

Article abstract of DOI:10.1055/s-2003-40213

New stannyl enamines derived from N-ethynyl oxazolidin-2-ones have been obtained. We describe for the first time the preparation of N-ethynyl oxazolidin-2-ones using trimethylsilylethynyl iodonium triflate. The first results of transmetallation and quenching experiments with prochiral carbonyl derivatives to give β-amino alcohols are also described.

Full text of DOI:10.1055/s-2003-40213

PAPER
1391
New Stannyl Enamides
New
Stannyl
E
é
namides bastien Naud, Jean-Christophe Cintrat
CEA/Saclay, Service de Marquage Moléculaire et Chimie Bio-organique, Bât. 547, Département de Biologie Joliot-Curie, 91191 Gif sur
Yvette cedex, FRANCE
Fax +33(1)69087991; E-mail: jean-christophe.cintrat@cea.fr
Received 17 March 2003; revised 4 April 2003
palladium tetrakis(triphenylphosphine) as shown in
Abstract: New stannyl enamines derived from N-ethynyl oxazoli-
Scheme 2. The results are summarized in Table 1.
din-2-ones have been obtained. We describe for the first time the
preparation of N-ethynyl oxazolidin-2-ones using trimethylsilyl-
ethynyl iodonium triflate. The first results of transmetallation and
quenching experiments with prochiral carbonyl derivatives to give
-amino alcohols are also described.
COPh
COPh
R3SnX
R3Sn
X
N
X
N
COPh
Bn
Bn
Bn
+
H
N
Pd(PPh3)4
R3Sn
Key words: enamide, hydrostannations, oxazolidinone, tin, yna-
mide
1
2
3
Scheme 2 Addition of organotin derivatives to ynamide 1.
Recently, ynamides and enamides have attracted much at-
tention in the literature due to their increased stability and
easier preparation procedure compared to enamines and
ynamines.1 We are mainly interested in -metallated ena-
mides as ‘umpolung’ synthons for the synthesis of non-
proteinogenic amino-acids, -amino-alcohols and we
have recently described the preparation2 and palladium
cross-coupling reactions of N-tosyl stannylated enam-
ines.3 With these compounds in hand, we next envisioned
the use of the well-known transmetallation procedure with
BuLi to obtain -lithiated enamides, as shown in
Scheme 1.
Table 1 Stannylation Reactions of Ynamide 1
Entry
R
X
Product (ratio)
2a/3a (85:15)
2b/3b (55:45)
2c
Yield (%)
80a
1
2
3
Bu
Bu
Me
H
Me3Si
Me3Sn
49a
86
a Yield refers to purified -stannyl isomers 2 only.
The addition of Bu3SnH to 1 gives a mixture of - and -
isomers however the -stannylated compound was
favoured and the desired product is obtained in very good
yield (entry 1). The introduction of Bu3SnSiMe3 was also
achieved in good yield although the regiochemical out-
come of this reaction was quite disappointing (almost no
regioselectivity was observed as seen in entry 2).6 Finally,
addition of hexamethylditin cleanly affords the distanny-
lated compound in a stereospecific fashion since the Z-
isomer was obtained as a single isomer (entry 3).
Tos
N
Tos
N
1) n-BuLi
Bu3Sn
X
E
X
Bn
Bn
2) E+
E+ = CO2, RCHO, RCOR', RX, ......
X = H, SnR3, SiMe3, alkyl, aryl....
Scheme 1 Transmetallation of -stannyl enamides.
Unfortunately, all attempts failed presumably due to -
elimination of TosLi. Therefore, we assumed that a Although these results were quite stimulating, we must
chelating group (such as a CO group for instance) could mention that the analysis of the products was complicated
be beneficial since the chelation could provide stabiliz- by the occurrence of rotamers in all the stannylated prod-
ation of the lithiated species as described with -amino ucts 2 and 3. Even when the NMR analyses were per-
alkyltins.4 Herein we describe the preparation of a range formed in THF at 323 K, broadening of the signals gave
of newly protected stannylated enamines as well as our complicated spectra. To avoid this limitation we turned
first results in the field of transmetallation of -monostan- our attention to cyclic species and since many oxazolidin-
nyl enamides derived from oxazolidin-2-ones.
2-ones are commercially available these cyclic carbam-
ates appeared to be attractive starting materials. First at-
tempts to obtain the protected ynamines 4 (Scheme 3)
using BuLi in toluene, Cs2CO3 in DMF were unsatisfacto-
ry giving low yields (less than 20%) of the expected prod-
uct. Changing the base to KHMDS greatly improved the
yield and the ynamines were obtained in 50–60% yield.
Our scheme for the synthesis of newly protected stannyl
enamines was inspired from the approach we described
previously, starting from N-benzoyl N-ethynyl benzy-
lamine (1) prepared by Witulski.5 Thus, addition of orga-
notin derivatives to 1 was conducted in the presence of
Synthesis 2003, No. 9, Print: 03 07 2003.
Art Id.1437-210X,E;2003,0,09,1391,1397,ftx,en;Z03903SS.pdf.
© Georg Thieme Verlag Stuttgart · New York
Interestingly, this approach can be extended to chiral 4-
substituted oxazolidinones and the results are summarized
in Table 2.

1392
S. Naud, J.-C. Cintrat
PAPER
O
O
R3
4, R3= SiMe3
5, R3= H
1) KHMDS
H
N
N
O
O
TBAF/H2O
toluene, 0 °C
R1
R1
R2
R2
2) R3
I+ Ph, TfO-
Scheme 3 Access to newly protected ethynyl amines.
Table 2 Synthesis of 3-Alkynyl Oxazolidinones
R3Sn
O
X
O
O
H
R3SnX
Pd(PPh3)4
R1
R2
R3
Product Yield (%)
N
O
Entry
1
N
O
N
O
+
X
R3Sn
R1
R1
R1
R2
R2
R2
H
H
H
H
SiMe3
H
4a
5a
48
90
α-isomer
β-isomer
5a-d
2
3
4
Ph
Ph
H
H
SiMe3
H
4b
5b
63
88
Scheme 4 Access to stannylated enamides derived from oxazolidi-
nones.
H
H
Bn
Bn
SiMe3
H
4c
5c
53
87
From the results described in the above table, easy access
to mono stannylated enamides derived from oxazolidino-
nes is possible although a mixture of - and -isomers is
always obtained (entries 1, 4, 7 and 10). Indeed, we ex-
pected a better selectivity at least with the 4-substituted
oxazolidinones based on steric7 or on electronic effects
(CO…Sn intramolecular bond). Nevertheless the stereo-
selectivity of this reaction was very good since for the -
stannylated isomers only the compounds resulting from a
cis-addition were detected in the NMR spectra of the
crude reaction mixture. Addition of Bu3SnSiMe3 ap-
peared to be more problematic since the yields were very
low for all oxazolidin-2-ones and the regioselectivity was
poor (entries 2, 5, 8 and 11).6 Finally, reaction with distan-
nylated compounds gave the desired products but, surpris-
ingly, the stereochemical outcome was lower than
expected since in some instances (entries 3 and 12) we ob-
H
H
i-Pr
i-Pr
SiMe3
H
4d
5d
60
89
As described in Table 2, N-trimethylsilylethynylation of
oxazolidin-2-ones is possible using KHMDS and trimeth-
ylsilylethynyl iodonium triflate and the presence of a sub-
stituent at C4 does not affect the yields (entries 2, 3, 4
compared to entry 1). Then the desilylation procedure
gave excellent yields of the ethynyl parent compounds. It
is noteworthy that the desilylation step can be performed
on the purified compounds 4 or on the crude mixture with-
out affecting the overall yield of compounds 5.
The 3-ethynyl oxazolidin-2-ones 5 were used in stannyla-
tion procedures with palladium catalysis according to
Scheme 4. The results are summarized in Table 3.
Table 3 Synthesis of Stannyl Enamides Derived from N-Ethynyl Oxazolidinones
Entry
1
Ynamine
5a
R
R1
H
R2
H
X
Product (ratio)
6 /6 (70:30)
(Z)-7 /7 (86:14)
8 (Z/E, 84:16)
9 /9 (64:36)
(Z)-10 /10 (78:22)
11
Yield (%)
55a
11a
63
Bu
Bu
Me
Bu
Bu
Bu
Bu
Bu
Bu
Bu
Bu
Me
H
2
5a
H
H
Me3Si
Me3Sn
H
3
5a
H
H
4
5b
Ph
Ph
Ph
H
H
46a
10a
35
5
5b
H
Me3Si
Bu3Sn
H
6
5b
H
7
5c
Bn
Bn
Bn
i-Pr
i-Pr
i-Pr
12 /12 (63:37)
(Z)-13 /13 (89:11)
14
38a
8a
8
5c
H
Me3Si
Bu3Sn
H
9
5c
H
43
10
11
12
5d
H
15 /15 (64:36)
(Z)-16 /16 (87:13)
17 (Z/E, 76:24)
57a
18a
71
5d
H
Me3Si
Me3Sn
5d
H
a Yield refers to purified -stannyl isomer.
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York

PAPER
New Stannyl Enamides
1393
served a small amount of the E-isomer resulting from egy complements Hegedus approach in which only the -
isomerization of the Z-isomer. The reaction appeared to isomer could be obtained.8 Indeed, our synthetic scheme
1
be clean (based on TLC and H NMR spectrum of the allows access to a wide range of mono-stannylated as well
crude reaction mixture) although the yields are a bit low as bis-metallated enamides (Sn/Sn or Sn/Si) that appear to
due to a very high sensitivity of the bis-stannylated enam- be promising tools for organic synthesis. Indeed, trans-
ides towards mild acidic conditions (even purification on metallations of the -(tin/carbon) bond and trapping with
silica gel using 2–5% of Et3N resulted in extensive proto- prochiral aldehydes or ketones affords -amino alcohols
destannylation at the -position).
but no assymetric induction could be obtained when start-
ing from enantiopure oxazolidinones. We are currently
working on the transmetallation or palladium catalyzed
reactions of the bis metallated congener in order to intro-
duce functionnal diversity at both C and C positions.
With these stannyl enamides in hand, we then studied the
transmetallation of the carbon–tin bond. Indeed, Hegedus8
has reported the transmetallation of a similar compound
but we wanted to check whether an asymmetric induction
could be possible when using the enantiomerically pure
compound and a prochiral electrophile. First, the experi-
mental conditions were optimized with the achiral starting
material. Thus, compound 6 was subjected to BuLi and
the -lithiated product was then trapped with some elec-
trophiles according to Scheme 5.
All reactions were performed in flame-dried Schlenk tubes or flasks
under an atmosphere of nitrogen. All commercially available com-
pounds were purchased from Aldrich or Acros and used without
further purification. THF was distilled under nitrogen from sodium
benzophenone ketyl. All new compounds were fully characterized
by spectroscopic methods (1H NMR and 13C NMR recorded on a
Bruker AC 300 spectrometerin CDCl3, MS, IR), HRMS and in the
case of crystalline compounds melting point was recorded. Chroma-
tography was preformed with pentane–Et2O.
O
O
O
O
1) n-BuLi
Bu3Sn
N
E
N
2) E+
N-Benzyl-N-ethynyl-benzamide (1)
E+ = H2O (18), D2O, hexanal (19), methyl isopropyl ketone (20)
FTIR (KBr): 3296, 2139, 1676 cm–1.
6α
1H NMR: = 2.84 (s, 1 H), 4.92 (s, 2 H, CH2), 7.29–7.63 (m, 8 H,
Ar), 7.87 (m, 2 H, Ar).
Scheme 5 Transmetallation/trapping of 6
13C NMR: = 52.6, 61.7, 78.5, 127.7, 128.0, 128.5, 131.4, 133.2,
135.8, 170.5.
Complete conversion of 6 into the lithiated congener is
only achieved using 2.4 equivalents9 of n-BuLi and al-
though trapping experiments with NH2O (N = 1, 2) or an
aldehyde gave good yields, 72% and 47%, of 18 and 19,
respectively, the yield dropped to 28% with a more steri-
cally crowded ketone such as methyl isopropyl ketone.
MS (ESI/TOF): m/z (%) = 258 (M + 23).
Stannylation of Ynamide 1; General Procedure
In a flame dried 100 mL flask, a catalytic amount of Pd(PPh3)4
(0.1%, 0.6 mg) is added to a solution of ynamide 1 (0.5 mmol) and
R3SnX (1.1 equiv, 0.55 mmol) in anhyd and degassed THF (25 mL).
The resulting mixture is degassed, placed under nitrogen and
warmed to 60 °C. The reaction was monitored by TLC. The mixture
was then concentrated and the residue was purified by flash chro-
matography over silica gel.
Then, the same experiments were conducted starting from
enantiomerically pure stannylated compound 12 using
identical prochiral carbonyl derivatives (Scheme 6).
Although moving to a 4-substituted oxazolidinone result-
ed in almost no change of the chemical yield (compared to
6 in Scheme 5) either with an aldehyde or a ketone, no
N-Benzyl-N-[(Z)-1-(tributylstannyl)vinyl]benzamide (2a)
FTIR (NaCl): 1632 cm–1.
1
diastereoselectivity could be seen in the H NMR spec-
1H NMR: = 0.87–1.90 (m, 27 H, 3 × Bu), 4.67 (s, 2 H, CH2), 4.90
[s, 1 H, 3JSn–H(cis) = 47.0 Hz], 5.20 [s, 1 H, 3JSn–H(trans) = 105.0, 109.9
Hz], 6.89–7.17 (m, 8 H, Ar), 7.28–7.30 (m, 2 H, Ar).
13C NMR: = 13.7 (1JC–Sn = 356.4, 371.1 Hz), 13.9, 27.7
(3JC–Sn = 58.6 Hz), 29.7 (2JC–Sn = 19.5 Hz), 52.0, 110.4
(2JC–Sn = 41.5 Hz), 126.4, 127.0, 127.2, 128.4, 128.8, 129.8, 136.9,
137.8, 150.7 (1JC–Sn = 410.2–427.3 Hz), 171.9.
trum analysis of the crude reaction mixture. This lack of
asymmetric induction has also been observed with -alkyl
aminostannanes derived from oxazolidinones, which only
display low diasteroselectivity.10
In conclusion, we have developed a new route to N-ethy-
nyl oxazolidin-2-ones11 starting from a readily available
alkynyl iodonium triflate salt12 and stannyl enamides de-
rived either from amides or oxazolidin-2-ones. This strat-
MS (CI): m/z (%) = 528 (M + 1, 100), 470 (M–57, 6).
O
O
O
O
O
1)
O
OH
O
R1 R2
n-BuLi
Li
N
R1
N
Bu3Sn
N
2) H2O
R2
- 100 °C
Bn
Bn
Bn
21 R1 = C5H11, R2 = H, yield = 57%
22 R1 = iPr, R2 = Me, yield = 26%
12α
Scheme 6 Trapping of enantiopure 12 with prochiral carbonyl derivatives.
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York

1394
S. Naud, J.-C. Cintrat
PAPER
HRMS (FAB): m/z calcd for C24H32NOSn [M – Bu]+·, 470.15059;
13C NMR : = 0.0 (1JC–Si = 58.6 Hz), 62.2, 70.7, 75.9, 90.6, 127.1,
found, 470.1508.
129.3, 129.6, 136.0, 155.1.
MS (CI): m/z (%) = 260 (M + 1, 15), 277 (M + 18, 100).
HRMS (EI): m/z calcd for C14H17NO2Si [M]+·, 259.10286; found,
259.10283.
N-Benzyl-N-[(Z)-1-(tributylstannyl)2-(trimethylsilyl)vinyl]-
benzamide (2b)
FTIR (NaCl): 1629 cm–1.
1H NMR: = 0.12 (s, 9 H, Me3Si), 0.67–1.74 (m, 27 H, 3 × Bu),
4.77 (s, 2 H, CH2), 6.15 (s, 1 H, 3JSn–H = 123.9, 130.0 Hz), 6.90–7.80
(m, 10 H, Ar).
(S)-4-Benzyl-3-[(trimethylsilyl)ethynyl]-1,3-oxazolidin-2-one
(4c)
White solid; mp: 109.4–109.8 °C; [ ]D25 96.2.
13C NMR:
= 0.3, 13.7 (1JC–Sn = 332.0, 344.2 Hz), 28.2
FTIR (KBr): 2148, 1764 cm–1.
(3JC–Sn = 63.5 Hz), 29.5 (2JC–Sn = 17.1 Hz), 52.7, 127.4, 128.1,
4
1H NMR: = 0.22 (s, 9 H, Me3Si), 2.93 (ddd, 1 H, Bn, J = 2.4,
128.5, 128.7, 129.6, 137.8, 138.3, 163.7.
2
3
2
3J = 7.9, J = 14.0 Hz), 3.22 (dd, 1 H, Bn, J = 3.6, J = 14.0 Hz),
4.09 (m, 1 H, CHO), 4.22–4.33 (m, 2 H, CHO, CHN), 7.17–7.41 (m,
5 H, Ar).
MS (ESI/TOF): m/z (%) = 600 (M + 1).
HRMS (FAB): m/z calcd for C27H40NOSiSn [M – Bu]+·, 542.19012;
found, 542.1903.
13C NMR: = –0.1 (1JC–Si = 56.2 Hz), 37.5, 58.0, 67.1, 75.9, 90.2,
127.3, 128.8, 129.2, 134.0, 155.1
N-Benzyl-N-[(Z)-bis(trimethylstannyl)vinyl]benzamide (2c)
FTIR (NaCl): 1626 cm–1.
MS (CI): m/z (%) = 274 (M + 1, 91), 291 (M + 18, 100)
HRMS (EI): m/z calcd for C15H19NO2Si [M]+·, 273.11851; found,
273.11551.
1H NMR: = 0.16 (s, 18 H, Me), 4.92 (s, 2 H, CH2), 6.35 (s, 1 H,
3JSn–H = 46.4, 2JSn–H = 152.0 Hz), 7.02–7.46 (m, 5 H, Ar).
13C NMR: = –7.4 (1JC–Sn = 336.9, 356.4 Hz), –4.6 (1JC–Sn = 346.7,
356.4 Hz), 52.8, 77.7, 127.4, 128.6, 129.7, 137.5, 138.3, 163.8,
170.5.
HRMS (FAB): m/z calcd for C21H28NOSn2 [M – Me]+·, 550.02149;
found, 550.0222.
(S)-4-Isopropyl-3-[(trimethylsilyl)ethynyl]-1,3-oxazolidin-2-
one (4d)
White solid; mp 105.4–105.8 °C; [ ]D25 39.8.
FTIR (KBr): 2187, 1769 cm–1.
1H NMR: = 0.13 (s, 9 H, Me3Si), 0.92 (d, 3 H, CH3, 3J = 4.3 Hz),
0.94 (d, 3 H, CH3, 3J = 4.3 Hz), 2.13 (m, 1 H, CH), 3.92 (ddd, 1 H,
CHN, 3J = 8.5, 5.5, 4.3 Hz), 4.07 (dd, 1 H, CHO, 3J = 5.5, 2J = 9.2
Hz), 4.32 (dd, 1 H, CHO, 3J = 8.5, 2J = 9.2 Hz).
13C NMR: = 0.1 (1JC–Si = 56.2 Hz), 15.4, 17.2, 29.4, 61.9, 65.0,
74.9, 91.2, 156.0.
Preparation of ‘Ynamides’; Typical Procedure
In a flame dried 250 mL flask, oxazolidin-2-ones (11.5 mmol) are
placed under vacuum for 15 min. The flask is then flushed with dry
nitrogen and anhyd toluene (125 mL) is added. The resulting sus-
pension is cooled to 0 °C and the resulting mixture degassed twice
by the freeze-thaw process. KHMDS (1.2 equiv, 27.6 mL, 0.5 M/
toluene) is added dropwise under nitrogen. The resulting mixture is
warmed to r.t. over 3 h and phenyl(trimethylsilylethynyl)iodonium
triflate (1.3 equiv, 6.71 g) is added portionwise. The resulting mix-
ture was stirred at r.t. overnight and the reaction was monitored by
TLC. The mixture was then filtered over a plug of silica gel (1 cm),
rinsed with Et2O (5 × 100 mL) and the solution was concentrated to
give a residue that was purified by flash chromatography over silica
gel.
MS (CI): m/z (%) = 226 (M + 1, 78), 243 (M + 18, 100).
HRMS (EI): m/z calcd for C11H19NO2Si [M]+·, 225.11851; found,
225.11902.
3-Ethynyl-1,3-oxazolidin-2-one (5a)
Yellow solid; mp 55.8–56.0 °C.
FTIR (NaCl): 3289, 2154, 1769 cm–1.
1H NMR: = 2.83 (s, 1 H), 3.92 (dd, 2 H, CH2N, 3J = 9.2, 6.7 Hz),
The deprotection step using TBAF is performed according to liter-
ature procedure.2,3,5
4.43 (dd, 2 H, CH2O, 3J = 9.2, 6.7 Hz).
13C NMR: = 46.6, 59.9, 63.4, 72.8, 156.4.
3-[(Trimethylsilyl)ethynyl]-1,3-oxazolidin-2-one (4a)
White solid; mp 79.2–79.7 °C.
FTIR (KBr) : 2188, 1758 cm–1.
MS (CI): m/z (%): 112 (M + 1).
HRMS (EI): m/z calcd for C5H5NO2 [M]+·, 111.03203; found,
111.03212.
1H NMR: = 0.14 (s, 9 H, Me3Si), 3.88 (dd, 2 H, CH2N, 3J = 6.7,
9.2 Hz), 4.38 (dd, 2 H, CH2O, 3J = 6.7, 9.2 Hz).
(R)-3-Ethynyl-4-phenyl-1,3-oxazolidin-2-one (5b)
Yellow solid; mp 63.4–64.0 °C; [ ]D25 –199.9.
13C NMR: = 0.1 (1JC–Si = 58.6 Hz), 47.0, 63.2, 73.7, 91.5, 156.0.
MS (CI): m/z (%) = 184 (M + 1, 8), 201 (M + 18, 100).
HRMS (EI): m/z calcd for C8H13NO2Si [M]+., 183.107156; found,
FTIR (NaCl): 3295, 2153, 1778 cm–1.
3
1H NMR: = 2.70 (s, 1 H), 4.23 (dd, 1 H, CHO, J = 7.3, 2J = 9.2
Hz), 4.73 (dd, 1 H, CHO, 3J = 8.5, 2J = 9.2 Hz), 5.07 (dd, 1 H, CHN,
3J = 7.3, 8.5 Hz), 7.30–7.53 (m, 5 H, Ar)
183.07182.
13C NMR: = 61.4, 61.8, 71.1, 71.8, 127.0, 129.5, 129.7, 135.9,
156.0
(R)-4-Phenyl-3-[(trimethylsilyl)ethynyl]-1,3-oxazolidin-2-one
(4b)
25
White solid; mp 100.3–100.9 °C; [ ]D –191.7
MS (CI): m/z (%) = 205 (M + 18).
FTIR (KBr): 2186, 1777, 1754 cm–1.
HR-MS (EI): m/z calcd for C11H9NO2 [M]+·, 187.06333; found,
3
1H NMR: = 0.04 (s, 9 H, Me3Si), 4.28 (dd, 1 H, CHO, J = 7.3,
187.06303.
2J = 9.2 Hz), 4.73 (dd, 1 H, CHO, 3J = 8.5, 2J = 9.2 Hz), 5.06 (dd, 1
H, CHN, 3J = 7.3, 8.5 Hz), 7.30–7.47 (m, 5 H, Ar).
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York

PAPER
New Stannyl Enamides
1395
3
2
(S)-4-Benzyl-3-ethynyl-1,3-oxazolidin-2-one (5c)
Hz), 4.39 (t, 2 H, CH2O, J = 7.3, J = 8.5 Hz), 5.65 (s, 1 H,
3JSn–H = 40.3, 2JSn–H = 134.3, 140.4 Hz)
Yellow solid; mp 61.5–62.3 °C; [ ]D25 104.9.
FTIR (KBr): 2184, 1753 cm–1.
13C NMR: = –6.6 (1JC–Sn = 341.8, 361.3 Hz), –4.3 (1JC–Sn = 344.2,
2
358.9 Hz), 43.6, 62.4, 121.1 (1JC–Sn = 478.5, 500.5, JC–Sn = 78.1
1H NMR: = 2.90 (dd, 1 H, CH2, 3J = 7.0, 2J = 14.0 Hz), 2.98 (s, 1
H), 3.12 (dd, 1 H, CH2, 3J = 3.0, 2J = 14.0 Hz), 4.06 (dd, 1 H, CHO,
3J = 9.2, 2J = 12.8 Hz), 4.24 (m, 2 H, CHO, CHN), 7.13–7.34 (m, 5
H, Ar).
Hz), 155.9, 156.5
HRMS (FAB): m/z calcd for C10H20NO2118Sn120Sn [M – Me]+·,
423.95321; found, 423.954.
13C NMR: = 37.4, 57.9, 61.9, 67.5, 71.9, 127.5, 129.0, 129.5,
134.0, 155.8.
(R)-4-Phenyl-3-[1-(tributylstannyl)vinyl]-1,3-oxazolidin-2-one
(9 )
25
MS (CI): m/z (%) = 202 (M + 1, 95), 219 (M + 18, 100)
HRMS (EI): m/z calcd for C12H11NO2 [M]+·, 201.07898; found,
201.07949.
[ ]D –18.8 (c = 1.2).
FTIR (NaCl): 1751 cm–1.
1H NMR: = 0.80–1.66 (m, 27 H, Bu), 4.09 (dd, 1 H, CHO,
3J = 4.3, 2J = 8.5 Hz), 4.46 [s, 1 H, 3JSn–H(cis) = 42.7 Hz], 4.67 (t, 1 H,
CHO, 3J = 8.5 Hz), 4.71 [s, 1 H, 3JSn–H(trans) = 95.8, 98.9], 5.16 (dd,
1 H, CHN, 3J = 4.3, 8.5 Hz), 7.16–7.42 (m, 5 H, Ar).
13C NMR: = 12.3 (1JC–Sn = 354.0, 368.7 Hz), 13.9, 27.5
(3JC–Sn = 61.3 Hz), 29.2 (2JC–Sn = 19.5 Hz), 59.2, 70.5,
107.4 (2JC–Sn = 29.3 Hz), 125.9, 128.6, 129.4, 139.1, 145.5
(1JC–Sn = 341.8, 356.5 Hz), 157.4.
(S)-4-Isopropyl-3-ethynyl-1,3-oxazolidin-2-one (5d)
[ ]D25 50.6 (c = 0.9).
FTIR (KBr): 3290, 2150, 1774 cm–1.
3
1H NMR: = 0.72 (d, 3 H, CH3, J = 4.3 Hz), 0.74 (d, 3 H, CH3,
3J = 4.3 Hz), 1.89–2.06 (m, 1 H, CH), 2.75 (s, 1 H), 3.81 (ddd, 1 H,
CHN, 3J = 8.5, 5.5, 4.3 Hz), 3.93 (dd, 1 H, CHO, 3J = 5.5, 2J = 9.2
Hz), 4.21 (dd, 1 H, CHO, 3J = 8.5, 2J = 9.2 Hz).
MS (CI): m/z (%) = 480 (M + 1, 100), 497 (M +1 85), 422 (M – 57,
14).
13C NMR: = 15.0, 16.9, 28.9, 60.7, 61.3, 64.9, 72.2, 156.3.
HRMS (EI): m/z calcd for C19H28NO2Sn [M – Bu]+·, 422.1142;
found, 422.11269.
MS (ESI/TOF): m/z (%) = 176 (M + 23).
HRMS (EI): m/z calcd for C8H11NO2 [M ]+·, 153.07898; found,
153.07853.
(R)-4-Phenyl-3-[(Z)-1-(tributylstannyl)-2-(trimethylsilyl)vinyl]-
1,3-oxazolidin-2-one (10 )
Metallated Enamines Derived from Oxazolidin-2-ones
Same procedure as above for compounds 2a–c.
[ ]D25 69.3 (c = 1.18).
FTIR (NaCl): 1744 cm–1.
3-[1-(Tributylstannyl)vinyl]-1,3-oxazolidin-2-one (6 )
1H NMR: = –0.04 (s, 9 H, Me3Si), 0.66–1.63 (m, 27 H, Bu), 4.11
FTIR (NaCl): 1748 cm–1.
3
2
3
(dd, 1 H, CHO, J = 7.9, J = 8.5 Hz), 4.65 (t, 1 H, CHO, J = 8.5
3
2
H NMR: = 0.80–1.64 (m, 27 H, Bu), 3.73 (dd, 2 H, CH2N,
Hz), 5.28 (dd, 1 H, CHN, J = 7.9, J = 8.5 Hz), 5.46 (s, 1 H,
3
3J = 7.9, 2J = 8.5 Hz), 4.40 (dd, 2 H, CH2O, J = 7.9, 2J = 8.5 Hz),
3JSn–H = 118.4, 123.3 Hz), 7.16–7.40 (m, 5 H, Ar).
3
3
4.51 [s, 1 H, JSn–H(cis) = 40.9 Hz], 4.83 [s, 1 H, JSn–H(trans) = 92.8,
13C NMR: = 0.4 (1JC–Si = 53.7 Hz), 13.5 (1JC–Sn = 341.8, 356.4
Hz), 13.7, 27.5 (3JC–Sn = 68.4 Hz), 29.1 (2JC–Sn = 17.1 Hz), 59.7,
70.2, 126.7, 128.3, 128.5 (2JC–Sn = 63.5 Hz), 128.9, 137.2, 154.2
(1JC–Sn = 385.7, 405.3 Hz), 156.8.
96.4 Hz].
13C NMR: = 12.1 (1JC–Sn = 354.0, 368.7 Hz), 13.8, 25.7,
27.4 (3JC–Sn = 61.0 Hz), 29.1 (2JC–Sn = 19.5), 43.3, 62.1,
68.0, 104.4 (2JC–Sn = 34.2 Hz), 147.1 (1JC–Sn = 339.4, 356.5
Hz), 157.0.
MS (CI): m/z (%) = 552 (M + 1, 100), 569 (M + 18, 8), 494 (M – 57,
60).
HRMS (FAB): m/z calcd for C22H36NO2SiSn [M – Bu]+·,
494.15373; found, 494.154.
MS (CI): m/z (%) = 404 (M + 1, 96), 421 (M + 18, 100), 346 (M –
57, 24).
HRMS (EI): m/z calcd for C16H30NO2Sn [M – Me]+·, 388.12985;
found, 388.13114.
(R)-4-Phenyl-3-[(Z)-bis(tributylstannyl)vinyl]-1,3-oxazolidin-2-
one (11)
[ ]D25 9.6 (c = 0.93).
3-[(Z)-1-(Tributylstannyl)-2-(trimethylsilyl)vinyl]-1,3-oxazoli-
din-2-one [(Z)-7 ]
FTIR (NaCl): 1747 cm–1.
FTIR (NaCl): 1745 cm–1.
1H NMR: = 0.62–1.66 (m, 54 H, Bu), 4.08 (dd, 1 H, CHO,
1H NMR: = 0.14 (s, 9 H, Me3Si), 0.75–1.61 (m, 27 H, Bu), 3.75 (t,
2 H, CH2N, 3J = 7.9 Hz), 4.36 (t, 2 H, CH2O, 3J = 7.9 Hz), 5.49 (s,
1 H, 3JSn–H = 114.1, 119.0 Hz).
3J = 6.7, J = 8.5 Hz), 4.64 (dd, 1 H, CHO, J = 8.5, J = 9.1 Hz),
2
3
2
3
3
5.27 (dd, 1 H, CHN, J = 6.7, 9.1 Hz), 5.54 (s, 1 H, JSn–H = 30.5,
3JSn–H = 125.7, 131.8 Hz), 7.14–7.42 (m, 5 H, Ar).
13C NMR:
= 0.9, 14.1 (1JC–Sn = 344.2, 359.9 Hz), 27.4
13C NMR: =11.2 (1JC–Sn = 332.0, 346.7 Hz), 13.2 (1JC–Sn = 344.2,
358.9 Hz), 13.2, 13.8, 27.3 (3JC–Sn = 53.7, 58.6 Hz), 27.7 (3JC–
Sn = 63.5, 68.4), 29.1 (2JC–Sn = 19.5 Hz), 29.4 (2JC–Sn = 19.5 Hz),
(3JC–Sn = 68.4 Hz), 29.1 (2JC–Sn = 19.5 Hz), 44.1, 62.3,
122.7 (2JC–Sn = 61.0 Hz), 156.5, 156.7.
HRMS (FAB): m/z calcd for C16H32NO2SiSn [M – Bu]+·,
418.12243; found, 418.1234.
59.7, 70.4, 125.2 (1JC–Sn = 405.3, 422.4, JC–Sn = 70.8 Hz), 126.5,
2
128.3, 129.1, 138.6, 153.6 (1JC–Sn = 417.5, 437.0, 2JC–Sn = 80.6 Hz),
156.9.
(Z)-3-[1,2-Bis(trimethylstannyl)vinyl]-1,3-oxazolidin-2-one (8)
MS (CI): m/z (%) = 769 (M+·).
HRMS (FAB): m/z calcd for C31H54NO2118Sn120Sn [M – Bu]+·,
FTIR (NaCl): 1738 cm–1.
1H NMR: = 0.21 (s, 9 H, Me, 2JSn–H = 52.5, 54.9 Hz), 0.23 (s, 9 H,
710.21926; found, 710.2244.
Me, 2JSn-H = 53.7, 56.2 Hz), 3.78 (dd, 2 H, CH2N, 3J = 7.3, 2J = 8.5
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York

1396
S. Naud, J.-C. Cintrat
PAPER
MS (ESI/TOF): m/z (%) = 446 (M + 1, 100), 388 (M – 57, 11).
(S)-4-Benzyl-3-[1-(tributylstannyl)vinyl]-1,3-oxazolidin-2-one
(12 )
HRMS (FAB): m/z calcd for C16H30NO2Sn [M – Bu]+·, 388.12985;
found, 388.1306.
[ ]D25 19.8 (c = 0.98).
FTIR (NaCl): 1746 cm–1.
(S)-4-Isopropyl-3-[(Z)-1-(tributylstannyl)-2-(trimethylsilyl)vi-
1H NMR: = 0.81–1.70 (m, 27 H, Bu), 2.74 (dd, 1 H, CH2, 3J = 8.5,
nyl]-1,3-oxazolidin-2-one
[(Z)-16 ]
2J = 13.4 Hz), 3.26 (dd, 1 H, CH2, 3J = 2.4, 2J = 13.4), 4.18 (m, 2 H,
3
CH2O), 4.38–4.48 (m, 1 H, CHN), 4.73 [s, 1 H, JSn–H(cis) = 42.1],
[ ]D25 –124.6 (c = 1.21).
5.18 [s, 1H, 3JSn–H(trans) = 95.2, 98.9 Hz], 7.14–7.37 (m, 5 H, Ar).
FTIR (NaCl): 1741 cm–1.
13C NMR: = 12.3 (1JC–Sn = 351.7, 368.7 Hz), 13.9, 27.5
(3JC–Sn = 61.0 Hz), 29.2 (2JC–Sn = 17.1 Hz), 35.8, 55.3, 66.4,
105.3 (2JC–Sn = 34.2 Hz), 127.3, 129.0, 129.4, 135.9, 145.9
(1JC–Sn = 339.4, 354.0 Hz), 156.7.
HRMS (FAB): m/z calcd for C20H30NO2Sn [M – Bu]+·, 436.12985;
found, 436.131.
1H NMR: = 0.14 (s, 9 H, Me3Si), 0.72–1.62 (m, 33 H, Bu, CH3),
4
3
2.20–2.36 (m, 1 H, CH), 4.09 (ddd, 1 H, CHO, J = 0.6, J = 7.3,
2J = 8.5 Hz), 4.24 (td, 1 H, CHO, 4J = 0.6, 3J = 8.5 Hz), 4.32–4.42
(m, 1 H, CHN), 5.69 (s, 1 H, 3JSn–H = 117.8, 123.3 Hz).
13C NMR: = 0.9 (1JC–Si = 53.7 Hz), 13.7 (1JC–Sn = 341.8, 356.5
Hz), 14.6, 18.2, 25.9, 27.7 (3JC–Sn = 65.9 Hz), 29.2, 58.1, 63.1, 126.7
(2JC–Sn = 107.4 Hz), 155.7 (1JC–Sn = 385.7, 405.3 Hz), 157.0.
(S)-4-Benzyl-3-[(Z)-1-(tributylstannyl)-2-(trimethylsilyl)vinyl]-
1,3-oxazolidin-2-one [(Z)-13 ]
MS (ESI/TOF): m/z (%) = 540 (M + 23, 79), 460 (M – 57, 100).
HRMS (FAB): m/z calcd for C19H38NO2SiSn [M – Bu]+·,
460.16938; found, 460.17.
[ ]D25 –97.4 (c = 2.1).
FTIR (NaCl): 1629cm–1.
1H NMR: = 0.20 (s, 9 H, Me3Si), 0.80–1.65 (m, 27 H, Bu), 2.61
(dd, 1 H, CH2, 3J = 9.1, 2J = 14.0 Hz), 3.29 (dd, 1 H, CH2, 3J = 3.1,
2J = 14.0 Hz), 4.10 (dd, 1 H, CHO, 3J = 6.1, 2J = 8.5) Hz, 4.24 (t, 1
H, CHO, 3J = 8.5, 2J = 8.5 Hz), 4.51–4.65 (m, 1 H, CHN), 5.87 (s,
1 H, 3JSn–H = 116.0, 120.9 Hz), 7.06–7.37 (m, 5 H, Ar).
13C NMR: = 1.0 (1JC–Si = 51.3 Hz), 13.8 (1JC–Sn = 341.8, 358.9
Hz), 13.9, 27.7 (3JC-Sn = 65.9 Hz), 29.3, 37.3, 55.3, 67.2,
127.2 (2JC–Sn = 65.9 Hz), 127.3, 129.1, 129.3, 136.1, 156.0
(1JC-Sn = 378.4, 395.5 Hz), 156.6.
(S)-4-Isopropyl-3-[(Z)-bis(trimethylstannyl)vinyl]-1,3-oxazoli-
din-2-one (17)
[ ]D25 –63.0 (c = 1.24).
FTIR (NaCl): 1735cm–1.
2
1H NMR: = 0.20 (s, 9 H, JSn–H = 52.5, 54.9 Hz), 0.21(s, 9 H,
3
2JSn–H = 53.1, 55.5 Hz), 0.79 (d, 3 H, J = 6.1 Hz), 0.87 (d, 3 H,
3J = 6.7 Hz), 2.28–2.41 (m, 1 H), 4.08–4.30 (m, 2 H, CH2O), 4.35–
3
2
4.45 (m, 1 H, CHN), 5.86 (s, 1 H, JSn–H = 43.3, JSn–H = 137.3,
MS (ESI/TOF): m/z (%) = 588 (M + 23, 100), 508 (M –57, 64).
144.1 Hz).
HRMS (FAB): m/z calcd for C23H38NO2SiSn [M – Bu]+·,
508.16938; found, 508.1688.
13C NMR: = –6.7 (1JC–Sn = 341.8, 356.4), –4.3 (1JC–Sn = 361.3,
376.0 Hz), 14.1, 17.9, 25.4, 57.3, 62.9, 124.3 (1JC–Sn = 473.6, 495.6,
2JC–Sn = 80.6 Hz), 154.8, 156.7.
(S)-4-Benzyl-3-[(Z)-bis(tributylstannyl)vinyl]-1,3-oxazolidin-2-
HRMS (FAB): m/z calcd for C13H26NO2Sn2 [M – Me.]+, 468.00075;
found, 468.0007.
one (14)
[ ]D25 –75.0 (c = 1.31).
FTIR (NaCl): 1744 cm–1.
-Stannyl Enamides Transmetallation/Trapping Experiments
A flame dried Schlenk tube is charged with the stannyl compound
(0.3 mmol), placed under vacuum and then under nitrogen. Anhyd
THF is added and the solution is cooled to –100 °C, and n-BuLi (2.4
equiv, 1.6 M/hexane, 0.72 mmol, 450 L) is slowly added at –
100 °C. The solution is stirred for 5 min and the electrophile (2.5
equiv, 0.75 mmol) is added (as a THF solution for ketones). Com-
pletion of the reaction is checked by TLC, H2O (2 mL) is added and
the cooling bath is removed and stirring is continued for 30 min.
The resulting mixture is diluted with THF (50 mL), dried over
Na2SO4, filtered and reduced in vacuo to a residue that was purified
by flash chromatography over silica gel.
1H NMR: = 0.82–1.72 (m, 54 H, Bu), 2.58 (dd, 1 H, CH2, 3J = 9.7,
2J = 13.4 Hz), 3.32 (dd, 1 H, CH2, 3J = 3.1, 2J = 13.4 Hz), 4.14 (dd,
1 H, CHO, 3J = 4.9, 2J = 8.5 Hz), 4.21 (t, 1 H, CHO, J = 8.5 Hz),
3
4.52–4.66 (m, 1 H, CHN), 6.03 (s, 1 H, 2JSn–H = 33.0, 3JSn–H = 124.5,
130.0 Hz), 7.14–7.42 (m, 5 H, Ar).
13C NMR: = 12.0 (1JC–Sn = 334.7, 349.1 Hz), 13.3 (1JC–Sn = 341.8,
361.3 Hz), 13.8, 13.9, 27.5 (3JC–Sn = 58.6 Hz), 27.7 (3JC–Sn = 65.9
Hz), 29.3, 29.4, 36.8, 55.2, 66.9, 123.7 (1JC–Sn = 400.4, 417.5,
2JC–Sn = 73.2 Hz), 127.3, 129.1, 129.2, 136.3, 155.0 (1JC–Sn = 417.5,
437.0, 2JC–Sn = 80.6 Hz), 156.3
HRMS (FAB): m/z calcd for C32H56NO2Sn2 [M – Bu]+·, 726.2355;
found, 726.2351.
3-[1-(1-Hydroxyhexyl)vinyl]-1,3-oxazolidin-2-one (19)
FTIR (NaCl): 3434 (br), 1747, 1620 cm–1.
1H NMR: = 0.77–0.97 (m, 3 H), 1.18–1.88 (m, 8 H), 2.30 (br s, 1
H, OH), 3.50–3.65 (m, 2 H, CH2O), 3.77–3.87 (m, 2 H, CH2N), 4.04
(dd, 1 H, 2J = 3.1, 4J = 1.8 Hz), 4.23 (dd, 1 H, 2J = 3.1, 4J = 2.4 Hz),
4.95–5.05 (m, 1 H).
(S)-4-Isopropyl-3-[1-(tributylstannyl)vinyl]-1,3-oxazolidin-2-
one (15 )
[ ]D25 –2.9 (c = 1.09).
FTIR (NaCl): 1743 cm–1.
13C NMR: = 13.9, 22.4, 23.5, 31.3, 35.3, 43.9, 59.3, 78.8, 80.5,
145.6, 157.4.
1H NMR: = 0.74–1.62 (m, 33 H, Bu, CH3), 2.40–2.56 (m, 1 H,
CH), 4.20 (m, 3 H, CHN, CH2O), 4.58 [s, 1 H, 3JSn–H(cis) = 42.7 Hz],
4.95 [s, 1 H, 3JSn–H(trans) = 96.4, 100.7 Hz).
MS (ESI/TOF): m/z (%) = 214 (M + 1).
13C NMR: = 12.4 (1JC–Sn = 351.6, 368.7 Hz), 13.9, 13.9, 25.3, 27.5
(3JC–Sn = 61.0 Hz), 29.2 (2JC–Sn = 19.5 Hz), 58.7, 62.8, 105.4
(2JC–Sn = 34.2 Hz), 145.7 (1JC–Sn = 346.7, 366.2 Hz), 157.1.
HRMS (EI): m/z calcd for C11H19NO3 [M]+., 213.13649; found,
213.13714.
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York

PAPER
New Stannyl Enamides
1397
3-[1-(1-Hydroxy-1,2-dimethylpropyl)vinyl]-1,3-oxazolidin-2-
one (20)
References
FTIR (NaCl) : 3440 (br), 1766 cm–1.
(1) (a) Rappoport, Z. The Chemistry of Enamines in the
Chemistry of Functional Groups; John Wiley and Sons: New
York, 1994. (b) Fuchs, J. R.; Funk, R. L. Org. Lett. 2001, 3,
3349. (c) Montgomery, J.; Wieber, G. M.; Hegedus, L. S. J.
Am. Chem. Soc. 1990, 112, 6255. (d) Gaulon, C.; Gizecki,
P.; Dahl, R.; Dujardin, G. Synlett 2002, 952. (e) Hsung, R.
P.; Zificsak, C. A.; Mulder, J. A.; Rameshkumar, C.; Wei,
L.-L. Tetrahedron 2001, 57, 7575. (f) Huang, J.; Xiong, H.;
Hsung, R. P.; Rameshkumar, C.; Mulder, J. A.; Grebe, T. P.
Org. Lett. 2002, 4, 2417. (g) Witulski, B.; Buschmann, N.;
Bergstrasser, U. Tetrahedron 2000, 56, 8473. (h) Tanaka,
T.; Hirano, S.; Urabe, H.; Sato, F. Org. Lett. 2003, 5, 67.
(i) Rainier, J. D.; Imbriglio, J. E. J. Org. Chem. 2000, 65,
7272. (j) Witulski, B.; Gossmann, M. Chem. Commun. 1999,
56, 1879.
1H NMR: = 0.90 (d, 3 H, 3J = 6.7 Hz), 1.00 (d, 3 H, 3J = 6.7 Hz),
3
1.48 (s, 3 H), 1.85 (hept, 1 H, J = 6.7 Hz), 2.28 (br s, 1 H, OH)
3
3.51–3.70 (m, 2 H, CH2N), 3.81 (dd, 2 H, CH2O, J = 5.5, 2J = 11
Hz), 3.98 (d, 1 H, 2J = 3.1 Hz), 4.20 (d, 1 H, 2J = 3.1 Hz).
13C NMR: = 16.0, 16.2, 24.8, 37.2, 43.8, 59.3, 80.1, 87.4, 128.3,
149.5.
MS (ESI/TOF) m/z (%): 200 (M + 1, 100), 222 (M + 23, 49).
HRMS (EI): m/z calcd for C10H17NO3 [M]+·, 199.12084; found,
199.12073.
(S)-4-Benzyl-3-[1-(1-hydroxyhexyl)vinyl]-1,3-oxazolidin-2-one
(21)
FTIR (NaCl): 3434 (br), 1760, 1621 cm–1.
(2) Minière, S.; Cintrat, J.-C. Synthesis 2001, 705.
(3) (a) Minière, S.; Cintrat, J.-C. J. Org. Chem. 2001, 66, 7385.
(b) Timbart, L.; Cintrat, J.-C. Chem.–Eur. J. 2002, 8, 1637.
(4) Pearson, W. H.; Lindbeck, A. C. J. Am. Chem. Soc. 1991,
113, 8546.
1H NMR: = 0.86 (t, 3 H, 3J = 6.7 Hz), 1.16–1.78 (m, 8 H), 3.10 (d,
3
3 H, CH2, OH, J = 7.3 Hz), 3.84–4.07 (m, 4 H, CH2O, CHN,
=CH), 4.12–4.20 (m, 1 H), 4.80–4.89 (m, 1 H), 7.16–7.34 (m, 5 H,
Ar).
(5) (a) Witulski, B.; Stengel, T. Angew. Chem. Int. Ed. 1998, 37,
489. (b) Witulski, B.; Gossmann, M. Synlett 2000, 1793.
(6) Hada, M.; Tanaka, Y.; Ito, M.; Murakami, M.; Amii, H.; Ito,
Y.; Nakatsuji, H. J. Am. Chem. Soc. 1994, 116, 8754.
(7) Alami, M.; Liron, F.; Gervais, M.; Peyrat, J.-F.; Brion, J.-D.
Angew. Chem. Int. Ed. 2002, 41, 1578.
(8) Lander, P. A.; Hegedus, L. S. J. Am. Chem. Soc. 1994, 116,
8126.
(9) Previous reports claimed that one equivalent is sufficient on
saturated analogs: Jeanjean, F.; Pérol, N.; Goré, J.; Fournet,
G. Tetrahedron Lett. 1997, 38, 7547.
(10) (a) Pearson, W. H.; Lindbeck, A. C.; Kampf, J. W. J. Am.
Chem. Soc. 1993, 115, 2622. (b) Tomoyasu, T.; Tomooka,
K.; Nakai, T. Synlett 1998, 1147.
(11) (a) Wei, L.-L.; Mulder, J. A.; Xiong, H.; Zificsak, C. A.;
Douglas, C. J.; Hsung, R. P. Tetrahedron 2001, 57, 459.
(b) Very recently an elegant approach to the same family of
compounds has been published : Frederick, M. O.; Mulder,
J. A.; Tracey, M. R.; Hsung, R. P.; Huang, J. J. Am. Chem.
Soc. 2003, 125, 2368.
13C NMR: = 13.9, 22.4, 23.4, 31.3, 33.5, 35.3, 57.5, 61.9, 78.7,
81.2, 126.7, 128.5, 129.1, 137.4, 145.5, 157.2.
MS (ESI/TOF): m/z (%) = 304 (M + 1, 100), 326 (M + 23, 11).
HRMS (EI): m/z calcd for C18H25NO3 [M]+·, 303.18344; found,
303.18337.
(S)-4-Benzyl-3-[1-(1-hydroxy-1,2-dimethylpropyl)vinyl]-1,3-
oxazolidin-2-one (22)
1H NMR: = 0.84 (d, 3 H, 3J = 6.7 Hz), 0.95 (d, 3 H, 3J = 6.7 Hz),
1.22 (s, 3 H), 1.74 (hept, 1 H, 3J = 6.7 Hz), 3.05–3.22 (m, 3 H, CH2,
OH), 3.79 (d, 1 H, 2J = 3.1 Hz), 3.76–3.94 (m, 2 H, CH2O), 3.97–
4.08 (m, 1 H, CHN), 4.04 (d, 1 H, 2J = 3.1 Hz).
13C NMR: =16.0, 16.2, 24.9, 33.6, 37.1, 57.3, 62.5, 80.2, 87.5,
126.7, 128.5, 129.3, 137.5, 149.9, 156.6.
MS (ESI/TOF): m/z (%) = 290 (M + 1, 70), 312 (M + 23, 100).
FTIR (NaCl): 3503 (br), 1735 cm–1.
HRMS (EI): m/z calcd for C17H23NO3 [M]+· 289.16779; found,
289.16829.
(12) (a) Murch, P.; Williamson, B. L.; Stang, P. J. Synthesis 1994,
1255. (b) Zhdankin, V. V.; Stang, P. J. Tetrahedron 1998,
54, 10927.
Synthesis 2003, No. 9, 1391–1397 ISSN 1234-567-89 © Thieme Stuttgart · New York