Synthesis of three-, five-, and six-membered heterocycles derived from new β-amino-α-(trifluoromethyl) alcohols

Article abstract of DOI:10.1002/hlca.201000232

Nucleophilic trifluoromethylation of α-imino ketones 2, derived from arylglyoxal, with Ruppert - Prakash reagent (CF₃SiMe₃) offers a convenient access to the corresponding O-silylated β-imino- α-(trifluoromethyl) alcohols. In a 'one-pot' procedure, by treatment with NaBH₄ , these products smoothly undergo reduction and desilylation yielding the expected β-amino-α-(trifluoromethyl) alcohols 4. The latter were used as starting materials for the synthesis of diverse trifluoromethylated heterocycles, including aziridines 5, 1,3-oxazolidines 8, 1,3-oxazolidin-2-ones 9, 1,3,2-oxazaphospholidine 2-oxides 10, 1,2,3-oxathiazolidine 2-oxides 11, and morpholine-2,3-diones 12. An optically active 5-(trifluoromethyl)-substituted 1,3-oxazolidin-2-one 9g was also obtained.

Full text of DOI:10.1002/hlca.201000232

Helvetica Chimica Acta – Vol. 93 (2010)
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Synthesis of Three-, Five-, and Six-Membered Heterocycles Derived
from New b-Amino-a-(trifluoromethyl) Alcohols
by Emilia Obijalska1) and Grzegorz Mloston´*
´
´
´
´
University of Łodz, Department of Organic and Applied Chemistry, Tamka 12, PL-91-403 Łodz
(phone: þ 48426355761; fax: þ 48426655162; e-mail: gmloston@uni.lodz.pl)
and Anthony Linden and Heinz Heimgartner*
Organisch-chemisches Institut der Universitꢀt Zꢁrich, Winterthurerstrasse 190, CH-8057 Zꢁrich
(phone: þ 41446354282; fax: þ 41446356812; e-mail: heimgart@oci.uzh.ch)
Dedicated to Professor Rolf Huisgen on the occasion of his 90th birthday
Nucleophilic trifluoromethylation of a-imino ketones 2, derived from arylglyoxal, with Ruppert –
Prakash reagent (CF3SiMe3) offers a convenient access to the corresponding O-silylated b-imino-a-
(trifluoromethyl) alcohols. In a ꢂone-potꢃ procedure, by treatment with NaBH4, these products smoothly
undergo reduction and desilylation yielding the expected b-amino-a-(trifluoromethyl) alcohols 4. The
latter were used as starting materials for the synthesis of diverse trifluoromethylated heterocycles,
including aziridines 5, 1,3-oxazolidines 8, 1,3-oxazolidin-2-ones 9, 1,3,2-oxazaphospholidine 2-oxides 10,
1,2,3-oxathiazolidine 2-oxides 11, and morpholine-2,3-diones 12. An optically active 5-(trifluoromethyl)-
substituted 1,3-oxazolidin-2-one 9g was also obtained.
1. Introduction. – A series of publications in the last two decades evidences the
growing interest in the elaboration of new methods for the preparation of b-amino-a-
(trifluoromethyl) alcohols in both chiral and achiral form (for a review, see [1]). In
general, there are three main strategies applied. The first one is the Henry reaction of
fluoral or hexafluoroacetone with nitro alkanes, followed by the reduction of the NO2
group. The second method is based on the ring opening of (trifluoromethyl)oxiranes
with primary or secondary amines. Finally, nucleophilic trifluoromethylation of a-
amino aldehydes or a-amino ketones with trimethyl(trifluoromethyl)silane (Ruppert –
Prakash reagent [2]) is probably the most frequently applied method [1]. In recent
reports from our group, another approach was applied, and the chemoselective
trifluoromethylation of the C¼O group of a-imino ketones 1 and 2 derived from
camphorquinone and arylglyoxals, respectively, was followed by treatment with NaBH4
[3]. In the latter case, a one-pot procedure leads simultaneously to desilylation and
selective reduction of the C¼N bond yielding the corresponding b-amino-a-(trifluoro-
methyl) alcohols 4 (Scheme 1). On the other hand, a-imino ketones of type 1, by
treatment with NaBH4, undergo only desilylation, and the reduction of the C¼N bond,
leading to amino alcohols 3, was achieved only by using diisobutylaluminum hydride
(DIBAL-H) for the final step of the procedure.
1
´
´
)
Part of the planned Ph.D. thesis of E. O., University of Łodz.
ꢄ 2010 Verlag Helvetica Chimica Acta AG, Zꢁrich

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Helvetica Chimica Acta – Vol. 93 (2010)
Scheme 1
In the case of amino alcohol 3 (R ¼ Me), the reaction of the major diastereoisomer
with phosgene yielded the desired 1,3-oxazolidin-2-one [3a]. This preliminary result
prompted us to explore a series of other easily available b-amino-a-(trifluoromethyl)
alcohols 4 for the synthesis of trifluoromethylated heterocycles with various ring sizes.
2. Results and Discussion. – In general, b-amino alcohols of type 4 are crystalline
and stable compounds, which can be stored for a long time without special precautions.
In one of the studied cases, i.e., 4a (Ar¼ 4-NO2C6H4, R ¼ t-Bu), the crystal structure
was established by X-ray crystallography (Fig. 1).
Fig. 1. ORTEP Plot [4] of the molecular structure of 4a (with 50% probability ellipsoids; arbitrary
numbering of the atoms)
The OH group of 4a forms an intramolecular H-bond with the amine N-atom, and
thereby creates a five-membered loop which can be described by a graph set motif [5]
of S(5). The NH group does not appear to form any significant H-bonds, although there
might be a very weak intramolecular interaction with one of the F-atoms.
The three-membered aziridines are heterocyclic compounds with fundamental
importance in organic synthesis [6]. Special interest is focused on aziridines, which
contain F-atoms or perfluorinated alkyl groups. However, the limited availability of
proper starting materials is reflected in a relatively low number of publications on
syntheses of F-containing aziridines [7].

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It is well-known that b-amino alcohols are convenient starting materials for the
synthesis of aziridines via direct or multistep cyclization [6a]. For this reason,
trifluoromethyl-substituted b-amino alcohols were studied as convenient substrates for
the preparation of aziridines with a new substitution pattern. First attempts were made
following Gabrielꢃs method, which is based on the initial conversion of a b-amino
alcohol to the corresponding b-halogeno amine and subsequent treatment with a base
[8]. In the case of 4b (Ar¼ Ph, R ¼ t-Bu), the attempted synthesis of the aziridine was
unsuccessful2).
A successful preparation of the desired aziridines 5b – 5e was achieved by the
cyclization reaction, using commercially available dichloro(triphenyl)phosphorane
(Ph3PCl2) according to the procedure described in [7a] (Scheme 2). A likely
intermediate for the ring closure is the zwitterion 6.
Scheme 2
In the case of 5b, 5c, and 5e, the products were formed exclusively and were isolated
as colorless oils in high yields (84 – 89%). Their structures were established on the basis
1
of the spectroscopic data. In the low-resolution H-NMR spectra (80 MHz) of the N-
isopropyl derivatives 5c and 5e, the signal of the aziridine CH2 group appears as a broad
singlet at ca. 2.45 ppm and a quadruplet with J(C,F) ¼ 3 – 4 Hz at higher field (ca.
2.05 ppm). The observed splitting of one of the signals results from a through-space
coupling of the CF3 group with the cis-oriented H-atom. Surprisingly, no geminal
1
coupling could be detected for the nonequivalent H-atoms at C(3). The H-NMR
spectra of the N-(tert-butyl) derivatives 5b and 5d displayed a similar signal pattern for
the CH2 group, but, surprisingly, the difference of the chemical shifts in the case of 5b
was much smaller (Dd < 0.1 ppm) than in the other cases (Dd ¼ 0.38 ꢀ 0.46 ppm).
Moreover, the signal of the through-space coupled H-atom of 5b appears at lower field,
in contrast to the other examples.
The reaction of 4c under the same conditions (refluxing MeCN) led to a mixture of
5d and a second product, in a ratio of ca. 1:1, which, in the 1H-NMR spectrum, showed,
in addition to a singlet for a t-Bu group (1.10 ppm), an AB system at 3.30 and 3.60 ppm
with JAB ¼ 9.7 Hz. In a small-scale experiment, carried out in refluxing toluene, the
aziridine 5d was formed only in traces, and the second product was the major com-
ponent of the reaction mixture. Several experiments, aimed at the optimization of the
2
)
Thionyl chloride (SOCl2) was used as the chlorinating agent and Et3N as the base. The starting
material was consumed, but only a complex mixture of products was obtained [8].

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Helvetica Chimica Acta – Vol. 93 (2010)
reaction conditions and the formation of 5d in higher yield, were unsuccessful. Chro-
matographic workup of the 1:1 mixture and distillation of the less-polar fraction yield-
ed pure 5d (42%). All attempts to isolate the other new product in pure form were in
vain, and the sample was always contaminated with 5d3). In an additional experiment,
the isolated aziridine 5d was heated in boiling toluene for 12 h, but, after cooling, no 7d
was found in the mixture (1H-NMR analysis). Thus, the by-product 7d was probably
formed competitively from an intermediate appearing on the pathway to aziridine 5d.
It is well-known that b-amino alcohols can be used for the synthesis of five-
membered heterocycles via substitution or condensation reactions. Thus, the reaction
of 4b with paraformaldehyde in boiling toluene yielded the trifluoromethyl-substituted
1,3-oxazolidine 8b in 62% yield (Scheme 3). On the other hand, the reaction of 4a, 4b,
4d, and 4f with phosgene in toluene at room temperature in the presence of Et3N led to
the corresponding 1,3-oxazolidin-2-ones 9 in excellent yields.
Scheme 3
Based on the 1H-NMR data, the structure of the second product was tentatively assigned as 2,2,5,5-
tetrasubstituted piperazine derivative 7d. It is worth mentioning that only one isomer of 7d was
formed in the described reaction. However, the configuration (cis or trans) of the substituents at
C(2) and C(5) remains unknown.
3
)

Helvetica Chimica Acta – Vol. 93 (2010)
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Nucleophilic trifluoromethylation of the a-imino ketone 2, with Ar¼ 4-MeOC6H4
and R ¼ (S)-Ph(Me)CH, led to the formation of the b-amino alcohol 4g as a 6 :4
mixture of diastereoisomers [3b]. Chromatographic separation on silica gel yielded the
pure diastereoisomers (according to 19F-NMR), and the minor one (more polar
fraction) was used for the reaction with phosgene. The corresponding 1,3-oxazolidin-2-
one 9g was obtained as a single product, and the absolute configuration of the two
stereogenic centers was unambiguously established by a single-crystal X-ray diffraction
analysis (Fig. 2).
Fig. 2. ORTEP Plot [4] of the molecular structure of 9g (with 50% probability ellipsoids; arbitrary
numbering of the atoms)
The space group permits the compound in the crystal to be enantiomerically pure,
but the absolute configuration of the molecule has not been determined. The
enantiomer used in the refinement was based on the known (S)-configuration of the 1-
phenylethyl substituent of the molecule. The compound thus has the (5R,1’S)-
configuration.
To obtain a derivative of a 1,3,2-oxazaphospholidine, a solution of the b-amino
alcohol 4b in toluene was treated with dichloro(phenyl)phosphane in the presence of
Et3N at 608. The product obtained thereby decomposed during typical workup, and,
therefore, the crude mixture was oxidized by addition of H2O2 at the same temperature.
The oxidized product, 1,3,2-oxazaphospholidine 2-oxide 10b, was isolated and purified
by layer chromatography in 68% yield as a 1:1 mixture of diastereoisomers
(Scheme 3). The attempted synthesis of the corresponding 2-sulfide by sulfurization

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of the initially formed 1,3,2-oxazaphospholidine with elemental sulfur was achieved
smoothly, but the obtained product spontaneously extruded sulfur during the workup
and decomposed to give an intractable mixture.
Finally, b-amino alcohols 4b and 4e were reacted with SOCl2 in CH2Cl2 in the
presence of Et3N at ꢀ 458 to yield the desired 1,2,3-oxathiazolidine 2-oxides 11b and
11e, respectively, as mixtures of diastereoisomers in good yields (ca. 4 :1 and 1:1 ratio,
resp.). In analogy to 10b, the stereoisomers could not be separated by standard
procedures.
As an example for the formation of a six-membered heterocycle, b-amino alcohols
4a and 4e were treated with oxalyl chloride in refluxing toluene. After crystallization
from CH2Cl2/hexane and toluene, respectively, the morpholine-2,3-diones 12a and 12e
were obtained as colorless crystals in 66 and 85% yield, respectively (Scheme 4).
Scheme 4
3. Conclusions. – The present study shows that the trifluoromethylated b-amino
alcohols 4, which can be prepared from monoimines of aryl glyoxals 2, are attractive
building blocks for the synthesis of trifluoromethyl-substituted three-, five-, and six-
membered heterocycles. The presence of the CF3 group, which is important for specific
changes of physicochemical and biological properties of organic substances [9],
enhances the attractiveness of the described approach. The examples of heterocycles
selected in this report can be further explored for the preparation of more complex
structures.
The authors thank the Polish Ministry for Science and Higher Education for a grant (Grant # N N204
130335; G. M. and E. O.), and financial support by F. Hoffmann-La Roche AG, Basel (H. H.) is
gratefully acknowledged.
Experimental Part
1. General. M.p.: Melt-Temp. II (Aldrich), in capillary; uncorrected. IR Spectra: NEXUS FT-IR
.
spectrophotometer; in KBr; absorptions in cmꢀ1 1H- and 13C-NMR spectra: Bruker Avance III 600
instrument (600 and 150 MHz, resp.); in CDCl3; d in ppm (d(TMS) 0 ppm), coupling constants J in Hz.
The 13C signals were assigned on the basis of HMQC experiments. 19F- and 31P-NMR spectra: Varian
Gemini BB 200 or Bruker Avance III 600 spectrometers; in CDCl3; with CCl3F or H3PO4, resp., as
references. Some spectra were also recorded with a Tesla BS spectrometer (80 MHz). HR-ESI-MS:
Finnigan MAT-95.
2. Starting Materials. The commercially available dichloro(triphenyl)phosphorane (Ph3PCl2),
dichloro(phenyl)phosphane (PhPCl2), oxalyl chloride ((COCl)2), paraformaldehyde ((CH2O)n), and
thionyl chloride (SOCl2) were purchased from Sigma-Aldrich, and soln. of phosgene in toluene (20%)

Helvetica Chimica Acta – Vol. 93 (2010)
1731
from Fluka. b-Amino-a-(trifluoromethyl) alcohols (4) were prepared according to the protocol
described in [3b]. Toluene was dried over Na, MeCN and CH2Cl2 over CaH2, and they were freshly
distilled prior to use.
3. Syntheses of Trifluoromethylated Aziridines; Reactions with Ph3PCl2. General Procedure. To the
soln. of the appropriate b-amino alcohol 4 (1 mmol) and Ph3PCl2 (646 mg, 2 mmol) in dry MeCN, Et3N
(505 mg, 5 mmol) was added while cooling the mixture in an ice-bath. Then, the mixture was heated to
reflux for 10 h. The solvents were evaporated in vacuo (i.v.; for 5c and 5e, a water-bath at r.t. was used).
The residue was washed with hexane, the precipitate was filtered off, and the solvent was evaporated. In
the case of 5d, the mixture of products was separated by prep. layer chromatography (PLC) on silica gel
with hexane/CH2Cl2 1:1 as the mobile phase.
1-(tert-Butyl)-2-phenyl-2-(trifluoromethyl)aziridine (5b). Yield: 205 mg (84%). Colorless oil,
purified by distillation at 908/0.1 Pa (bulb-to-bulb). IR (film): 3062m, 3042m, 2976vs, 2934s, 2969vs,
2875m, 1604w, 1500m, 1474m, 1449m, 1364s, 1354s, 1334vs, 1217vs, 1173vs, 1147vs, 1114s, 1093m, 1052s,
1029m, 1010m, 826w. 1H-NMR (600 MHz): 7.58 – 7.57 (m, 2 arom. H); 7.39 – 7.35 (m, 3 arom. H); 3.82 (s,
MeO); 2.36 (br. q, 4J(H,F) ¼ 1.2, 1 H of CH2); 2.30 (br. s, 1 H of CH2); 0.88 (s, t-Bu). 13C-NMR
(150 MHz): 131.8 (1 arom. CH); 131.2 (1 arom. C); 129.1, 128.4 (4 arom. CH); 124.8 (q, 1J(C,F) ¼ 276.2,
CF3); 54.5 (Me3C); 47.0 (q, 2J(C,F) ¼ 34.7, Cq); 27.9 (Me3C); 27.3 (q, 3J(C,F) ¼ 0.6, CH2). 19F-NMR
(565 MHz): ꢀ 76.4 (s, CF3). HR-ESI-MS (MeOH þ NaI): 266.11259 ([M þ Na]þ, C13H16F3NNaþ; calc.
266.11271); 244.13067 ([M þ 1]þ, C13H17F3Nþ; calc. 244.13076).
1-Isopropyl-2-phenyl-2-(trifluoromethyl)aziridine (5c). Yield: 188 mg (82%). Colorless oil, purified
by distillation at ca. 308/0.1 Pa (bulb-to-bulb). IR (film): 3062m, 3033m, 2973vs, 2934s, 2873s, 1604w,
1581w, 1501s, 1463s, 1449s, 1369vs, 1356vs, 1444m, 1324s, 1281w, 1203vs, 1174vs, 1139vs, 1051s, 1027s,
1011s, 896w, 855w. 1H-NMR (600 MHz): 7.54 – 7.53 (m, 2 arom. H); 7.41 – 7.39 (m, 3 arom. H); 2.48 (br. s,
1 H of CH2); 2.05 (br. s, 1 H of CH2); 1.62 (br., Me2CH); 1.13 (d, 3J(H,H) ¼ 6.0, 1 Me of Me2CH); 1.08 (d,
3J(H,H) ¼ 4.2, 1 Me of Me2CH). 1H-NMR (80 MHz): 7.63 – 7.28 (m, 5 arom. H); 2.45 (br. s, 1 H of CH2);
2.05 (q, J(H,F) ¼ 3.6, 1 H of CH2); 1.86 – 1.45 (br. m, Me2CH); 1.14 (d, 3J(H,H) ¼ 6.0, 1 Me of Me2CH);
1.05 (d, 3J(H,H) ¼ 4.2, 1 Me of Me2CH). 13C-NMR (150 MHz): 131.8 (1 arom. CH); 129.6 (1 arom. C);
1
2
128.6 (4 arom. CH); 124.8 (q, J(C,F) ¼ 276.2, CF3); 52.2 (Me2CH); 49.0 (q, J(C,F) ¼ 34.7, Cq); 33.1
(CH2); 22.6, 22.4 (Me2CH). 19F-NMR (565 MHz): ꢀ 71.6 (s, CF3). HR-ESI-MS (MeCN þ NaI):
230.11510 ([M þ 1]þ, C12H15F3Nþ; calc. 230.11511).
1-(tert-Butyl)-2-(4-methoxyphenyl)-2-(trifluoromethyl)aziridine (5d; less-polar fraction). Yield:
110 mg (40%). Colorless semi-solid; distilled at 1408/0.1 Pa (bulb-to-bulb). IR (film): 3046m, 2973vs,
2937vs, 2909s, 2841m, 1604vs, 1579m, 1518vs, 1466s, 1444m, 1391m, 1364s, 1336vs, 1295vs, 1254vs, 1217vs,
1171vs, 1146vs, 1111s, 1052vs, 1035s, 1009m, 861m. 1H-NMR (600 MHz): 7.39 – 7.35 (m, 3 arom. H); 7.48 –
4
7.47, 6.89 – 6.87 (2m, 2 arom. H); 3.82 (s, MeO); 2.69 (br. s, 1 H of CH2); 2.31 (q, J(H,F) ¼ 0.6, 1 H of
1
CH2); 0.88 (s, t-Bu). 13C-NMR (150 MHz): 124.9 (q, J(C,F) ¼ 276.2, CF3); 160.1, 123.0 (2 arom. C);
139.2, 113.8 (4 arom. CH); 55.2 (MeO); 54.4 (Me3C); 46.3 (q, 2J(C,F) ¼ 34.7, Cq); 27.9 (Me3C); 27.4 (q,
3J(C,F) ¼ 0.6, CH2). 19F-NMR (565 MHz): ꢀ 71.6 (s, CF3). CI-MS (isobutane): 274 (100, [M þ 1]þ). HR-
ESI-MS (MeCN þ NaI): 274.14131 ([M þ 1]þ, C14H19F3NOþ; calc. 274.14133).
1,4-Di(tert-Butyl)-2,5-bis(4-methoxyphenyl)-2,5-bis(trifluoromethyl)piperazine (7d; more-polar
fraction, partially contaminated with 5d). Decomposes at r.t. Yield: 100 mg (36%). Pale yellow oil.
1H-NMR (80 MHz): 7.65 – 7.49, 7.00 – 6.81 (2m, 8 arom. H); 3.81 (s, 2 MeO); 3.60, 3.30 (AB, JAB ¼ 9.7,
2 CH2); 1.09 (s, 2 t-Bu).
1-Isopropyl-2-(4-methoxyphenyl)-2-(trifluoromethyl)aziridine (5e). Yield: 198 mg (84%). Colorless
oil, distilled at 708/0.1 Pa (bulb-to-bulb). IR (film): 3046m, 2973vs, 2937vs, 2909s, 2841m, 1604vs, 1579m,
1518vs, 1466s, 1444m, 1391m, 1364s, 1336vs, 1295vs, 1254vs, 1217vs, 1171vs, 1146vs, 1111s, 1052vs, 1035s,
109m, 861m. 1H-NMR (600 MHz): 7.46 – 7.45 (m, 2 arom. H); 6.93 – 6.91 (m, 2 arom. H); 3.83 (s, MeO);
2.46 (br. s, 1 H of CH2); 2.00 (br. s, 1 H of CH2); 1.62 (br., Me2CH); 1.11, 1.08 (2d, 3J(H,H) ¼ 6.0,
Me2CH). 1H-NMR (80 MHz): 7.53 – 7.36 (m, 2 arom. H); 6.99 – 6.80 (m, 2 arom. H); 3.81 (s, MeO); 2.42
(br. s, 1 H of CH2); 1.99 (q, J(H,F) ¼ 3.3, 1 H of CH2); 1.85 – 1.42 (br. m, 1 H, Me2CH); 1.12, 1.05 (2d,
3J(H,H) ¼ 6.0, Me2CH). 13C-NMR (150 MHz): 160.4, 127.6 (2 arom. C); 133.0, 113.9 (4 arom. CH); 124.8
(q, 1J(C,F) ¼ 273.0, CF3); 55.3 (MeO); 52.2 (Me2CH); 48.3 (q, 2J(C,F) ¼ 35.0, Cq); 33.2 (CH2); 22.5, 22.4

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(Me2CH). 19F-NMR (565 MHz): ꢀ 71.9 (s, CF3). HR-ESI-MS (MeOH þ NaI): 260.12581 ([M þ 1]þ,
C13H17F3NOþ; calc. 260.12568).
4. Synthesis of Five-Membered Heterocycles. 4.1. Reaction with (CH2O)n. In a round-bottom flask
with a Dean – Stark trap, a mixture of 4a (261 mg, 1 mmol) and paraformaldehyde (45 mg, 1.5 mmol) in
toluene (ca. 10 ml) was heated to reflux for 12 h. Then, the solvent was evaporated, and the crude product
was purified by filtration through a pad of neutral Al2O3 (eluent: hexane/CH2Cl2 9 :1).
3-(tert-Butyl)-5-phenyl-5-(trifluoromethyl)-1,3-oxazolidine (8b). Yield: 169 mg (62%). Colorless,
viscous oil. IR (film): 3063w, 2972m, 2939m, 2876w, 1643w, 1496w, 1450w, 1389w, 1367m, 1307m, 1258m,
1
1176vs, 1164vs, 1086s, 1062m, 1030m, 1019m, 992w, 920w, 859w. H-NMR (600 MHz): 7.43 – 7.42 (m, 2
arom. H); 7.30 – 7.25 (m, 3 arom. H); 4.63, 4.59 (2d, 2J(H,H) ¼ 10.2, CH2); 3.52, 3.31 (2d, 2J(H,H) ¼ 10.2,
CH2); 0.95 (s, t-Bu). 13C-NMR (150 MHz): 137.7 (1 arom. C); 128.7, 128.5, 126.8 (5 arom. CH); 125.5 (q,
2
1J(C,F) ¼ 285.3, CF3); 84.2 (q, J(C,F) ¼ 28.7, Cq); 83.1, 53.3 (2 CH2); 52.6 (Me3C); 25.7 (Me3C). 19F-
NMR (188 MHz): ꢀ 77.03 (s, CF3). HR-ESI-MS (MeOH þ NaI): 296.12297 ([M þ Na]þ,
C14H18F3NNaOþ; calc. 296.12327), 274.14134 ([M þ 1]þ, C14H19F3NOþ; calc. 274.14133).
4.2. Cyclization with COCl2. General Procedure. To the soln. of an appropriate amino alcohol 4
(1 mmol) in dry toluene (2 ml), Et3N (253 mg, 2.5 mmol) was added; an enantiomerically pure
diastereoisomer 4g [3b] was used for preparation of 9g. Then, a soln. of phosgene was added dropwise
while cooling the mixture in an ice bath, and the mixture was magnetically stirred overnight. Next day, the
solvent was evaporated, and crude products were purified by filtration through a plug of neutral Al2O3
using hexane/CH2Cl2 7:3 as an eluent.
3-(tert-Butyl)-5-(4-nitrophenyl)-5-(trifluoromethyl)-1,3-oxazolidin-2-one (9a). Yield: 316 mg
(95%). Colorless crystals. M.p. 154 – 1568 (petroleum ether/CH2Cl2). IR (KBr): 3116w, 3078w, 2983m,
2939w, 1767vs (C¼O), 1608m, 1522vs, 1478m, 1416m, 1352vs, 1459w, 1310s, 1295vs, 1272s, 1238s, 1212s,
1192vs, 1177vs, 1141m, 1073s, 1041m, 1001s, 861m, 849s. 1H-NMR (600 MHz): 8.32 – 8.30, 7.73 – 7.71 (2m,
4 arom. CH); 4.28, 3.86 (2d, 2J(H,H) ¼ 9.6, CH2); 1.42 (s, t-Bu). 13C-NMR (150 MHz): 153.3 (CO); 149.0,
141.4 (2 arom. C); 127.6, 124.5 (4 arom. CH); 123.5 (q, 1J(C,F) ¼ 285.3, CF3); 77.5 (q, 2J(C,F) ¼ 31.7, Cq);
54.9 (Me3C); 50.5 (CH2); 27.5 (Me3C). 19F-NMR (565 MHz): ꢀ 81.0 (s, CF3). ESI-MS (MeOH): 355
(100, [M þ Na]þ). HR-ESI-MS (MeOH þ NaI): 355.08775 ([M þ Na]þ, C14H15F3N2NaOþ4 ; calc.
355.08761), 333.10557 ([M þ 1]þ, C14H16F3N2O4þ ; calc. 333.10567).
3-(tert-Butyl)-5-phenyl-5-(trifluoromethyl)-1,3-oxazolidin-2-one (9b). Yield: 275 mg (96%). Color-
less crystals. M.p. 53 – 558 (petroleum ether). IR (KBr): 2980w, 2913w, 1767vs (C¼O), 1635w, 1452w,
1
1412w, 1370w, 1291w, 1238m, 1171s, 1050w, 1035w, 1011w, 758w. H-NMR (600 MHz): 7.51 – 7.49 (m, 2
arom. H); 7.45 – 7.43 (m, 3 arom. H); 4.23, 3.88 (2d, 2J(H,H) ¼ 9.3, CH2); 1.41 (s, t-Bu). 13C-NMR
1
(150 MHz): 153.8 (CO); 134.6 (1 arom. C); 129.7, 128.7, 125.9 (5 arom. CH); 123.8 (q, J(C,F) ¼ 283.7,
CF3); 77.6 (q, 2J(C,F) ¼ 30.9, Cq); 54.3 (Me3C); 50.5 (CH2); 27.3 (Me3C). 19F-NMR (188 MHz): ꢀ 80.5 (s,
CF3). ESI-MS (MeOH): 310 (100, [M þ Na]þ). HR-ESI-MS (MeOH þ NaI): 310.10266 ([M þ Na]þ,
C14H16F3NNaOþ2 ; calc. 310.10253), 288.12028 ([M þ 1]þ, C14H17F3NOþ2 ; calc. 288.12059).
3-(tert-Butyl)-5-(4-methoxyphenyl)-5-(trifluoromethyl)-1,3-oxazolidin-2-one (9d). Yield: 310 mg
(97%). Colorless crystals. M.p. 107 – 1098 (petroleum ether/CH2Cl2). IR (KBr): 2982w, 2942w, 1763vs
(C¼O), 1611m, 1518s, 1459w, 1411m, 1294s, 1252vs, 1205s, 1171vs, 1073m, 1023s, 1011m, 844w. 1H-NMR
(600 MHz): 7.42 – 7.40, 6.96 – 6.93 (2m, 4 arom. H); 4.19 (d, 2J(H,H) ¼ 9.6, 1 H of CH2); 3.84 (dq,
4
2J(H,H) ¼ 9.6, J(H,F) ¼ 0.6, 1 H of CH2); 3.82 (s, MeO); 1.40 (s, t-Bu). 13C-NMR (150 MHz): 160.5
(CO); 153.9, 126.6 (2 arom. C); 127.3, 114.1 (4 arom. CH); 123.8 (q, 1J(C,F) ¼ 283.5, CF3); 77.5 (q,
2J(C,F) ¼ 30.2, Cq); 55.3 (MeO); 54.2 (Me3C); 50.5 (CH2); 27.3 (Me3C). 19F-NMR (188 MHz): ꢀ 80.8 (s,
CF3). ESI-MS (MeOH): 340 (100, [M þ Na]þ), 318 (45, [M þ 1]þ). HR-ESI-MS (MeOH þ NaI):
340.11330 ([M þ Na]þ, C15H18F3NNaO3þ ; calc. 340.1310), 318.113083 ([M þ 1]þ, C15H19F3NOþ3 ; calc.
318.13115).
3-(tert-Butyl)-5-(trifluoromethyl)-5-[4-(trifluoromethyl)phenyl]-1,3-oxazolidin-2-one (9f). Yield:
246 mg (92%). Colorless crystals. M.p. 117 – 1198 (hexane/CH2Cl2). IR (KBr): 2989w, 2920w, 1766vs
(C¼O), 1622w, 1417m, 1371w, 1332s, 1291w, 1181s, 1135m, 1107m, 1072m, 1018m, 852w. 1H-NMR
2
(600 MHz): 7.73 – 7.71, 7.66 – 7.64 (2m, 4 arom. H); 4.26, 3.85 (2d, J(H,H) ¼ 9.6, CH2); 1.41 (s, t-Bu).
13C-NMR (150 MHz): 153.6 (CO); 138.7 (1 arom. C); 132.3 (q, 2J(C,F) ¼ 33.2, 1 arom. C); 126.8 (2 arom.
CH), 126.1 (q, 3J(C,F) ¼ 3.0, 2 arom. CH); 123.8 (q, 1J(C,F) ¼ 271.7, CF3); 123.7 (q, 1J(C,F) ¼ 285.3,

Helvetica Chimica Acta – Vol. 93 (2010)
1733
CF3); 77.6 (q, 2J(C,F) ¼ 31.7, Cq); 54.7 (Me3C); 50.6 (CH2); 27.5 (Me3C). 19F-NMR (565 MHz): ꢀ 60.0 (s,
CF3); ꢀ 81.3 (s, CF3). ESI-MS: 378 (100, [M þ Na]þ). HR-ESI-MS (MeOH þ NaI): 378.08994 ([M þ
Na]þ, C15H15F6NNaO2þ ; calc. 378.08992); 356.10780 ([M þ 1]þ, C15H16F6NOþ2 ; calc. 356.10797).
(5R)-5-(4-Methoxyphenyl)-3-[(S)-1-phenylethyl]-5-(trifluoromethyl)-1,3-oxazolidin-2-one (9g).
Yield: 332 mg (91%). Colorless crystals. M.p. 120 – 1228 (hexane/CH2Cl2). [a]2D0 ¼ þ31 (c ¼ 1, CH2Cl2).
IR (KBr): 3066w, 3030w, 1755vs (C¼O), 1612w, 1517m, 1439w, 1281m, 1254s, 1213w, 1182vs, 1034s, 1024s,
832w. 1H-NMR (600 MHz): 7.43 – 7.39 (m, 4 arom. H); 7.36 – 7.34 (m, 3 arom. H); 6.96 – 6.95 (m, 2 arom.
H); 5.27 (q, 3J(H,H) ¼ 7.2, CH); 3.84 (s, MeO); 3.72, 3.70 (2d, 2J(H,H) ¼ 9.5, CH2); 1.55 (d, 2J(H,H) ¼
7.2, Me). 13C-NMR (150 MHz): 160.9 (C¼O); 155.2, 138.7, 126.4 (3 arom. C); 123.8 (q, 1J(C,F) ¼ 283.7,
CF3); 128.5, 127.6, 127.1, 126.6, 114.4 (9 arom. CH); 79.2 (q, 3J(C,F) ¼ 31.7, Cq); 52.0 (CH2); 48.0 (CH);
16.2 (Me). 19F-NMR (565 MHz): ꢀ 81.8 (s, CF3). HR-ESI-MS (MeOH þ NaI): 388.11329 ([M þ Na]þ,
C19H18F3NNaOþ3 ; calc. 388.11310).
Suitable crystals for a crystal-structure determination were obtained from hexane/CH2Cl2 by slow
evaporation of the solvent.
4.3. Cyclization with PhPCl2. To the soln. of 4a (261mg, 1 mmol) in dry toluene (Ar atmosphere), a
soln. of PhPCl2 (286 mg, 1.6 mmol) in toluene was added dropwise while cooling the round-bottom flask
in an ice-bath. Then, Et3N (354 mg, 3.5 mmol) was added, and the mixture was heated for 3.5 h. The
precipitate (Et3N · HCl) was filtered off, a 30% soln. of H2O2 (400 mg, 3.5 mmol) was added to the
filtrate, and the mixture was heated at 608 for 3 h. The org. phases were diluted with H2O and extracted
with CH2Cl2. Org. layers were combined, dried (Na2SO4), and solvents were evaporated. The product
was isolated, as a mixture of two diastereoisomers, by PLC on silica gel with CH2Cl2/hexane 1:1 as the
eluent.
3-(tert-Butyl)-5-phenyl-5-(trifluoromethyl)-1,3,2-oxazaphospholidine 2-Oxide (10b). Yield: 260 mg
(68%). Yellow oil. IR (film): 3062w, 2976m, 2940w, 2889w, 1683w, 1592w, 1485w, 1450m, 1440m, 1399w,
1369w, 1310s, 1270vs, 1244vs, 1226vs, 1174vs, 1140s, 1119s, 1071s, 1043s, 1014s, 923w, 861s. 1H-NMR
(600 MHz): major isomer: 7.97 – 7.93, 7.71 – 7.73, 7.58 – 7.54, 7.50 – 7.39, 7.33 – 7.32 (5m, 10 arom. H); 4.17
(dd, 2J(H,H) ¼ 9.6, 3J(H,P) ¼ 7.8, 1 H of CH2); 4.00 (dd, 2J(H,H) ¼ 9.6, 3J(H,P) ¼ 9.6, 1 H of CH2); 1.18
(s, t-Bu); minor isomer: 7.97 – 7.93, 7.71 – 7.73, 7.58 – 7.54, 7.50 – 7.39, 7.33 – 7.32 (5m, 10 arom. H); 4.32 (dd,
2J(H,H) ¼ 10.2, 3J(H,P) ¼ 7.8, 1 H of CH2); 3.90 (dd, 2J(H,H) ¼ 10.2, 3J(H,P) ¼ 10.2, 1 H of CH2); 1.28 (s,
t-Bu). 13C-NMR (150 MHz): major isomer: 123.9 (qd, 1J(C,F) ¼ 283.8, 3J(C,P) ¼ 9.1, CF3); 113.90 (2
arom. CH); 81.3 (q, 2J(C,F) ¼ 31.7, Cq); 53.2 (d, 2J(C,P) ¼ 4.5, Me3C); 51.5 (d, 2J(C,P) ¼ 9.1, CH2); 28.4 (d,
3J(C,P) ¼ 3.0, Me3C); minor isomer: 123.7 (q, 1J(C,F) ¼ 285.3, 3J(C,P) ¼ 3.6, CF3); 80.9 (q, 2J(C,F) ¼ 31.7,
2
2
2
Cq); 50.9 (d, J(C,P) ¼ 10.6, CH2); 53.3 (d, J(C,P) ¼ 4.5, Me3C); 50.9 (d, J(C,P) ¼ 10.6, CH2); 28.5 (d,
3J(C,P) ¼ 3.0, Me3C); complex signals attributed to aromatic C-atoms of both diastereoisomers were
found between 126.2 and 135.3 ppm. 19F-NMR (188 MHz): major isomer: ꢀ 78.46 (s, CF3); minor
isomer: ꢀ 79.31 (s, CF3). HR-ESI-MS (MeOH þ NaI): 406.11509 ([M þ Na]þ, C19H21F3NNaO2Pþ; calc.
406.11542), 384.13295 ([M þ 1]þ, C19H22F3NO2Pþ; calc. 384.13347).
4.4. Reactions with SOCl2. General Procedure. To the soln. of an amino alcohol 4 (1 mmol) and Et3N
(253 mg, 2.5 mmol) in dry CH2Cl2, SOCl2 (92 mg, 1.1 mmol) was added dropwise (Ar atmosphere), while
cooling the mixture in an acetone/dry ice bath (ca. ꢀ 458). The mixture was stirred for 3 h, diluted with
H2O, and extracted with CH2Cl2. The org. layers were combined, dried (anh. Na2SO4), filtered, and the
solvent was evaporated. Products were obtained as a mixture of diastereoisomers and, without
separation, were purified by filtration through silica gel pad using hexane/CH2Cl2 1:1 as the eluent.
3-(tert-Butyl)-5-phenyl-5-(trifluoromethyl)-1,2,3-oxathiazolidine 2-Oxide (11b). Yield: 260 – 280 mg
(85 – 91%, mixture of two diastereoisomers). Yellow oil. The ratio of the diastereoisomers (ca. 1:4) was
determined for a freshly prepared sample, and no change of this ratio was observed during the storage. IR
(film): 3063w, 2976s, 2935m, 1738w, 1603w, 1496m, 1450m, 1399w, 1372m, 1300s, 1269s, 1204vs, 1174vs,
1113m, 1074m, 1008s, 959s, 876w. 1H-NMR (600 MHz): major isomer: 7.54 – 7.52 (m, 2 arom. H); 7.43 –
2
2
7.40 (m, 3 arom. H); 4.27 (d, J(H,H) ¼ 9.6, 1 H of CH2); 3.87 (dq, J(H,H) ¼ 9.6, 4J(H,F) ¼ 0.6, 1 H of
CH2); 1.30 (s, t-Bu); minor isomer: 7.54 – 7.52 (m, 2 arom. H); 7.43 – 7.40 (m, 3 arom. H); 4.18 (d,
2J(H,H) ¼ 10.2, 1 H of CH2); 3.98 (dq, 2J(H,H) ¼ 10.2, 4J(H,F) ¼ 1.2, 1 H of CH2); 1.41 (s, t-Bu).
13C-NMR (150 MHz): major isomer: 134.7 (1 arom. C); 129.4, 128.4, 125.9 (5 arom. CH); 123.1 (q,
1J(C,F) ¼ 282.3, CF3); 89.8 (q, 2J(C,F) ¼ 30.8, Cq); 54.9 (Me3C); 48.8 (CH2); 28.4 (Me3C); minor isomer:

1734
Helvetica Chimica Acta – Vol. 93 (2010)
1
135.7 (1 arom. C); 129.3, 128.5, 126.3 (5 arom. CH); 123.7 (q, J(C,F) ¼ 285.3, CF3); 90.1 (q, 2J(C,F) ¼
29.7, Cq); 54.8 (Me3C); 49.5 (CH2); 29.6 (Me3C). 19F-NMR (188 MHz): major isomer: ꢀ 75.2 (s, CF3);
minor isomer: ꢀ 78.8 (s, CF3). HR-ESI-MS (MeOH þ NaI): 330.07490 ([M þ Na]þ, C13H16F3NNaO2Sþ;
calc. 330.07461).
3-Isopropyl-5-(4-methoxyphenyl)-5-(trifluoromethyl)-1,2,3-oxathiazolidine 2-Oxide (11e). Yield:
220 mg (71%). Yellow oil. Mixture of diastereoisomers; a ratio of ca. 15 :85 was determined for a
freshly prepared sample. After several weeks storage in the refrigerator, a ca. 1:1 mixture of both
isomers was formed. IR (film): 3018w, 2972m, 2939m, 2845w, 1612s, 1518vs, 1467m, 1377w, 1297s, 1260vs,
1207s, 1173vs, 1145vs, 1092s, 1031s, 996s, 884w, 834s. 1H-NMR (600 MHz): major isomer: 7.45 – 7.42 (m, 2
2
arom. H); 6.95 – 6.90 (m, 2 arom. H); 4.12, 3.83 (2d, J(H,H) ¼ 9.6, CH2); 3.81 (s, MeO); 3.47 (sept.,
3J(H,H) ¼ 6.6, Me2CH); 1.24, 1.23 (2d, 3J(H,H) ¼ 6.6, Me2CH); minor isomer: 7.45 – 7.42 (m, 2 arom. H);
6.95 – 6.90 (m, 2 arom. H); 4.13, 3.84 (2d, 2J(H,H) ¼ 9.6, CH2); 3.82 (s, MeO); 3.49 (sept., 3J(H,H) ¼ 6.0,
Me2CH); 1.38, 1.30 (2d, 3J(H,H) ¼ 6.0, Me2CH). 13C-NMR (150 MHz): major isomer: 160.4 (1 arom. C);
1
127.3 (2 arom. CH); 126.6 (1 arom. C); 123.1 (q, J(C,F) ¼ 283.8, CF3); 113.90 (2 arom. CH); 90.2 (q,
2J(C,F) ¼ 31.7, Cq); 55.3 (MeO); 51.8 (CH2); 47.2 (Me2CH); 21.6, 21.5 (Me2CH); minor isomer: 160.3 (1
arom. C); 127.6 (2 arom. CH); 126.6 (1 arom. C); 123.7 (q, 1J(C,F) ¼ 285.3, CF3); 113.86 (2 arom. CH);
90.5 (q, 2J(C,F) ¼ 30.2, Cq); 55.3 (MeO); 51.0 (CH2); 47.23 (Me2CH); 21.7, 21.4 (Me2CH). 19F-NMR
(188 MHz): major isomer: ꢀ 79.1 (s, CF3); minor isomer: ꢀ 75.7 (s, CF3). HR-ESI-MS (MeOH þ NaI):
346.06928 ([M þ Na]þ, C13H16F3NNaO3Sþ; calc. 346.06952).
5. Syntheses of Six-Membered Heterocycles. Reaction with Oxalyl Chloride. General Procedure. To a
soln. of amino alcohol 4 (1 mmol) in dry toluene (5 ml), oxalyl chloride (207 mg, 1.3 mmol) was added
dropwise. The mixture was refluxed for 4 h. Then, toluene was evaporated, and the crude product was
crystallized from an appropriate solvent.
4-(tert-Butyl)-6-(4-nitrophenyl)-6-(trifluoromethyl)morpholine-2,3-dione (12a). Yield: 306 mg
(85%). Colorless crystals. M.p. 143 – 1448 (toluene). IR (KBr): 3120w, 3092w, 2979w, 2938w, 1792vs
(C¼O), 1693vs (C¼O), 1610w, 1530vs, 1423w, 1355vs, 1293m, 1192vs, 1147vs, 1127s, 1059w, 944m, 855m.
1H-NMR (200 MHz): 8.37 – 8.35, 7.75 – 7.74 (2m, 4 arom. H); 4.32, 4.22 (2d, 2J(H,H) ¼ 14.4, CH2); 1.39 (s,
t-Bu). 13C-NMR (150 MHz): 154.3, 152.6 (2 CO); 149.3, 138.3 (2 arom. C); 127.8, 124.6 (4 arom. CH);
122.4 (q, 1J(C,F) ¼ 286.8, CF3); 81.4 (q, 2J(C,F) ¼ 30.2, Cq); 59.8 (Me3C); 45.2 (CH2); 19.0 (Me3C). 19F-
NMR (565 MHz): ꢀ 75.7 (s, CF3). HR-ESI-MS (MeCN þ NaI): 383.08240 ([M þ Na]þ,
C15H15F3N2NaOþ5 ; calc. 383.08253).
4-Isopropyl-6-(4-methoxyphenyl)-6-(trifluoromethyl)morpholine-2,3-dione (12e). Yield: 210 mg,
(66%). Colorless crystals. M.p. 148 – 1508 (CH2Cl2/hexane). IR (KBr): 3026w, 2291w, 2978w, 2848w,
1776vs (C¼O), 1689vs (C¼O), 1609m, 1517s, 1481m, 1443m, 1342m, 1308m, 1263vs, 1180vs, 1160vs,
1
1137s, 1112m, 1028m, 991m, 835m. H-NMR (600 MHz): 7.40 – 7.38, 6.96 – 6.94 (2m, 4 arom. H); 4.75 –
4.65 (m, Me2CH); 4.12, 3.94 (2d, 2J(H,H) ¼ 14.1, CH2); 3.83 (s, MeO); 1.21 (2d, 3J(H,H) ¼ 6.9, Me2CH).
13C-NMR (150 MHz): 161.1, 154.4 (2 CO); 151.8, 122.7 (2 arom. C); 122.6 (q, 1J(C,F) ¼ 285.3, CF3); 114.7,
127.6 (4 arom. CH); 81.4 (q, 2J(C,F) ¼ 31.7, Cq); 55.42 (MeO); 46.1 (Me2CH); 42.2 (CH2); 19.0 (Me2CH).
19F-NMR (188 MHz): ꢀ 76.7 (s, CF3). HR-ESI-MS (MeCN þ NaI): 354.09216 ([M þ Na]þ,
C15H16F3NNaOþ4 ; calc. 354.09236).
6. X-Ray Crystal-Structure Determination of 4a and 9g (Table, and Figs. 1 and 2)4). All
measurements were performed on a Nonius KappaCCD diffractometer [10] using graphite-monochro-
mated MoKa radiation (l 0.71073 ꢅ) and an Oxford Cryosystems Cryostream 700 cooler. The data
collection and refinement parameters are given in the Table, and views of the molecules are shown in
Figs. 1 and 2. Data reduction was performed with HKL Denzo and Scalepack [11]. The intensities were
corrected for Lorentz and polarization effects but not for absorption. Equivalent reflections were
merged. The structures were solved by direct methods using SHELXS97 [12], which revealed the
positions of all non-H-atoms. The non-H-atoms were refined anisotropically. The amine and OH H-
atoms of 4a were placed in the positions indicated by a difference electron-density map, and their
4
)
CCDC-779928 and -779929 contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from the Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.

Helvetica Chimica Acta – Vol. 93 (2010)
1735
positions were allowed to refine with individual isotropic displacement parameters, while the OꢀH and
NꢀH distances were restrained to suitable values. All remaining H-atoms and all H-atoms of 9g were
placed in geometrically calculated positions and refined using a riding model where each H-atom was
assigned a fixed isotropic displacement parameter with a value equal to 1.2 Ueq of its parent C-atom
(1.5 Ueq for the Me groups). The refinement of each structure was carried out on F2 using full-matrix
least-squares procedures, which minimized the function Sw(F2o ꢀ Fc2 )2. In both cases, one reflection,
whose intensity was considered to be an extreme outlier, was omitted from the final refinement. Neutral
atom scattering factors for non-H-atoms were taken from [13a], and the scattering factors for H-atoms
were taken from [14]. Anomalous dispersion effects were included in Fc [15]; the values for f’ and f’’ were
those of [13b]. The values of the mass attenuation coefficients are those of [13c]. All calculations were
performed using the SHELXL97 [16] program.
Table. Crystallographic Data for Compound 4a and 9g
4a
9g
Crystallized from
Empirical formula
Formula weight
hexane/Et2O
C13H17F3N2O3
306.28
hexane/CH2Cl2
C19H18F3NO3
365.35
Crystal color, habit
Crystal dimensions [mm]
Temperature [K]
colorless, tablet
0.08 ꢁ 0.15 ꢁ 0.15
160(1)
colorless, prism
0.25 ꢁ 0.28 ꢁ 0.35
160(1)
Crystal system
Space group
triclinic
P1
monoclinic
P21
ꢀ
Z
2
2
Reflections for cell determination
2649
2045
2q Range for cell determination [8]
4 – 50
4 – 55
Unit cell parameters a [ꢅ]
6.8276(3)
9.3896(4)
12.7135(5)
73.634(2)
76.284(2)
89.260(2)
758.45(6)
1.341
6.4391(2)
14.7662(4)
9.0768(2)
90
93.755(2)
90
861.18(4)
1.409
0.116
b [ꢅ]
c [ꢅ]
a [8]
b [8]
g [8]
V [ꢅ3]
Dx [g cmꢀ3
]
m(MoKa) [mmꢀ1
Scan type
]
0.119
w
f and w
55
2q(max) [8]
50
Total reflections measured
Symmetry-independent reflections
Reflections with I > 2s(I)
Reflections used in refinement
Parameters refined; restraints
Final R(F) [I > 2s (I) reflections]
wR(F2) (all data)
14693
2674
1927
2673
201; 2
0.0685
0.2083
0.1037; 0.7456
1.031
20611
2049
1930
2048
238; 1
0.0309
0.0797
0.0481; 0.0874
1.075
Weighting parameters [a; b]a)
Goodness-of-fit
Secondary extinction coefficient
Final Dmax/s
–
0.044(6)
0.001
0.17; ꢀ 0.17
0.001
0.59; ꢀ 0.32
D1 (max; min) [e ꢅꢀ3
]
a) wꢀ1 ¼ s2(F2o ) þ (aP)2 þ bP where P ¼ (Fo2 þ 2F2c )/3.

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Helvetica Chimica Acta – Vol. 93 (2010)
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Received June 15, 2010