Stereoselectivity of the nucleophilic F-alkylation of carbonylated carbohydrates

Article abstract of DOI:10.1016/S0957-4166(97)00620-4

The addition of F-alkyl organometallics to carbonylated carbohydrates 1-3 was carried out using trimethylsilyl or bromomagnesium reagents. The results are strongly dependent upon both the nature of the metal and of the substrate. Compounds 1 and 2 were transformed with high stereoselectivity into the L-ido adduct using F-organomagnesium reagents, whereas the D-allo adduct was obtained with complete stereoselectivity using fluoride activated addition of F-organosilanes on compound 3. Comparison with literature data emphasizes the enhanced stereoselectivity exhibited by perfluoroorganometallic reagents. The difference between the stereoselectivity of the addition of magnesium versus silyl reagents was attributed to chelation effects.

Full text of DOI:10.1016/S0957-4166(97)00620-4

Pergamon
Tetrahedron: Asymmetry 9 (1998) 213–226
Stereoselectivity of the nucleophilic F-alkylation of carbonylated
carbohydrates
Sandrine Lavaire, Richard Plantier-Royon and Charles Portella ∗
Laboratoire Réactions Sélectives et Applications, Associé au CNRS (UMR 6519), Université de Reims, Faculté des Sciences,
BP 1039, 51687 Reims Cedex 2, France
Received 16 October 1997; accepted 2 December 1997
Abstract
The addition of F-alkyl organometallics to carbonylated carbohydrates 1–3 was carried out using trimethylsilyl
or bromomagnesium reagents. The results are strongly dependent upon both the nature of the metal and of
the substrate. Compounds 1 and 2 were transformed with high stereoselectivity into the L-ido adduct using F-
organomagnesium reagents, whereas the D-allo adduct was obtained with complete stereoselectivity using fluoride
activated addition of F-organosilanes on compound 3. Comparison with literature data emphasizes the enhanced
stereoselectivity exhibited by perfluoroorganometallic reagents. The difference between the stereoselectivity of the
addition of magnesium versus silyl reagents was attributed to chelation effects. © 1998 Elsevier Science Ltd. All
rights reserved.
Carbohydrates, renewable raw materials, are attractive building blocks for the synthesis of a wide
range of products. They are involved as ‘chirons’ in the synthesis of enantiomerically pure compounds.1
Their polyhydroxylic functionality brings about a hydrophilic character exploited in the surfactant field.2
On the other hand, fluorinated derivatives of carbohydrates have attracted the attention of organic and
bioorganic chemists, due to the properties induced by fluorine. Weakly fluorinated sugars, containing
one or two fluorine atoms, were widely studied as part of bioactive molecules.3 More recently, synthesis
of some deoxytrifluorosugars4,5 or C-trifluoromethyl sugars including nucleoside analogues,6,7 were
reported. Some highly fluorinated carbohydrates (containing a perfluoroalkyl chain longer than CF3)
were synthesized as surfactants, for example for the formulation of biocompatible oxygen carriers.8 Most
of the reported carbohydrate derived fluorinated surfactants contain a hydrocarbon spacer between the
hydrophilic sugar moiety and the F-alkyl chain, due especially to two main reasons: (i) some syntheses
were based on O- or S-alkylation or -glycosidation with F-alkyl alkanols or -thiols on which the F-alkyl
group is necessarily branched at a remote position from the functional carbon9 (the hydroxyl group is
highly deactivated in alcohols such as F-alkylmethanol); (ii) other syntheses involved radical F-alkylation
of O-allyl derivatives or glycal derivatives.10
∗
Corresponding author. E-mail: charles.portella@univ-reims.fr
0957-4166/98/$19.00 © 1998 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(97)00620-4

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Within a program on the synthesis and applications of new fluorinated carbohydrates derivatives, we
have undertaken the study of the direct grafting of an F-alkyl chain (including CF3) onto the sugar
carbon backbone by radical11 or nucleophilic12 F-alkylation. This paper deals with the F-alkylation
and trifluoromethylation of carbonylated derivatives 1–3 with F-organomagnesium reagents and F-alkyl
trimethylsilanes (F-alkyl TMS). Comparison of the two types of reagents, and on the other hand,
comparison with the reported results on the addition of non-fluorinated nucleophiles is discussed to
emphasize the specific behaviour of the fluorinated reagents.
1. Results
1.1. Starting compounds and reagents
Two types of carbonylated substrates were considered, which vary by the nature of a hydroxyl
protecting group or the carbonyl function. 3-O-Benzyl- and 3-O-allyl-1,2-O-isopropylidene-α-D-xylo-
pentodialdo-1,4-furanoses 1 and 2, and 1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose 3
were prepared according to conventional procedures from D-glucose. To simplify the following descrip-
tion, we will subsequently name these compounds ‘pentodialdoses’ and ‘3-oxo-glucose’, respectively.
The reagent used as a source of nucleophilic trifluoromethyl was trifluoromethyltrimethylsilane
(TFMTMS),13 prepared according to reported procedures.14 Long chain F-alkylations were carried
out with F-organomagnesium bromides,15 prepared in situ from F-alkyliodides and ethylmagnesium
bromide, or with F-alkyltrimethylsilane,16 in order to compare the influence of the metal on the
stereoselectivity.
1.2. Additions on the ‘pentodialdoses’
The trifluoromethylation of 1 and 2 with TFMTMS was carried out at 0°C in methylene chloride
and induced with a catalytic amount of n-tetrabutylammonium difluorotriphenylstannate (DFTPS).17
These conditions, already used in this laboratory,18 gave better results than conventional solvent and
catalyst (ether or THF, TBAF). The results are reported in Scheme 1 and Table 1 (entries 1–3), including
a literature result about the use of trifluoromethylzinc iodide (under sonication) as the nucleophilic
source (entry 3),5 to emphasize the effectiveness of TFMTMS methodology. The addition to 1, yielded
quantitatively a mixture of intermediate silyl ethers which was easily hydrolyzed to give a mixture of
the two epimeric L-ido and D-gluco derivatives 4 and 5 with an 80/20 ratio. The epimers were separated
by chromatography and the stereochemical assignment was based on literature data. The minor D-gluco
derivative 5 is a crystalline compound whose X-ray structure and specific rotation has been already
reported.5
Scheme 1.

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215
Table 1
F-Alkylation of 1,2-O-isopropylidene-3-O-alkyl-α-D-xylo-pentodialdo-1,4-furanoses
Table 2
Selected 1H and 13C NMR dataa for compounds 4–10
The assumption that the same stereoselectivity was obtained for the allyl derivative 2, giving the
corresponding allyl L-ido/D-gluco 6/7 as a 88/12 mixture, is consistent with good correlation in the
1H NMR and 13C NMR data of 6/7 versus 4/5 (Table 2). In particular, H-3 and C-5 are more shielded
(∆δ at 0.25 and 1.5 ppm, respectively) for L-ido derivatives, and the hydroxylic proton is coupled only
for the D-gluco derivatives. The relative shielding of H-3 and the coupling of the hydroxylic proton are
consistent with similar observations in non-fluorinated derivatives in this series.19,20
Addition of 1 or 2 to a solution of F-organomagnesium reagents in ether at −45°C gave the results

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depicted in Scheme 1 and Table 1 (entries 4–7). The addition gave highly stereoselectively the L-ido
adducts 8 and 10, since the minor D-gluco epimers 9 and 11 could be observed only as traces in the NMR
spectra.
The actual yields did not exceed 68%, but the reaction was very clean and the yield versus the converted
starting material is quantitative. Changing the experimental conditions (time and/or temperature) did not
improve the conversion. In order to assess the role of the F-alkyl chain versus the nature of the metal on
the stereoselectivity of the addition, F-butyltrimethylsilane was added to 1 under conditions similar to
the ones used for trifluoromethylation and at −45°C. A diastereoselectivity comparable to that observed
in the addition of TFMTMS was observed (8a/9a=80/20), but the conversion and the yields were in the
same range as for the addition of RFMgBr (Table 1, entries 8–9).
1.3. Addition on ‘3-oxo-glucose’
The results obtained when the same reagents were reacted in the same conditions with 3 are depicted
in Scheme 2 and Table 3. As above, the long chain reagents gave partial conversion and high selectivity
(yield versus converted starting material; entries 2–4). In contrast to the addition to 1 and 2, silyl reagents
add with complete stereoselectivity to the β-face, giving the D-allose derivative 12 or 13 as a unique
isolable and observable product, whereas a mixture of epimers D-allo and D-gluco (13/14=75/25) was
obtained from magnesium reagents. The two epimers were easily separated by silica gel chromatography.
We have already given the spectral features of the trifluoromethyl D-allo derivative 12.7
Scheme 2.
The configuration of the other F-alkyl derivatives was assigned according to correlations with 12 and
to the following observations (Table 4): (i) the hydroxylic proton is more shielded (∆δ at 1.3 ppm) in the
D-allose series; (ii) a splitting of H-2 signal (J=1.1 Hz) and C-5 signal (J=5.9 Hz) was observed for the
long F-alkyl branched D-allose derivatives 13a and 13b, probably because of a coupling through space
with fluorine; (iii) C-3 and C-5 for all derivatives of D-glucose series are more deshielded (∆δ at 1.5
Table 3
F-Alkylation of 1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose 3

S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
217
Table 4
Selected NMR data for compounds 12–14
and 2.5 ppm, respectively) than for D-allose derivatives; (iv) the difluoromethylene linked to C-3 is more
deshielded for D-gluco derivatives (cis relation to the oxygen at C-2).
2. Discussion
Two major observations can be drawn from these results. The yields of trifluoromethylation with
TFMTMS are quantitative, and the conversion is not complete with long chain F-alkyl reagents, whatever
the associated metal. In contrast, the nature of the metal is responsible for the stereochemical course of
the addition, and the relative stereochemistry depends on the substrate: high stereoselectivity is observed
with magnesium reagents for pentodialdoses substrates, with silyl reagents for 3-oxo glucose substrates.
The lower conversion in additions with long chain reagents may be related to a slower attack of a
highly oxygenated substrate by a highly hydrophobic reagent. Such an explanation is consistent with the
limited stability of F-organometallic reagents.15 The specific stereochemical behaviour of each substrate
deserves separate discussion, as does a comparison with the literature data to determine the specificity of
the additions on fluorinated nucleophiles.
2.1. Stereoselectivity of the F-alkylation of the ‘pentodialdoses’ 1 and 2
Several papers have reported on the addition of various non-fluorinated nucleophilic reagents to 1 or
related compounds. The results and references are summarized in Table 5. We can ignore the first reported
result21 (entry 1) which is in complete disagreement with the other literature data, probably because the
isolation of the L-ido derivative was performed by crystallization, possibly ignoring the epimer in the
mother liquor. Considering the other data, we can deduce the following observations:
(i) magnesium reagents generally gave the L-ido derivative19,20,22,23 stereoselectively (entries 2–5);
(ii) this stereoselectivity may be improved with addition of Lewis acid such as titanium tetrachloride
or zinc chloride (entry 2) or be reversed by increasing the size of the counter metal by addition of
crown ether (entry 3) or titanium tetraisopropoxide (entry 5); and

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Table 5
Organometallic additions on ‘pentodialdo’ derivatives: literature data
(iii) silyl reagents (entries 6 and 7) gave a high L-ido selectivity only with added oxygenophilic chelating
Lewis acid.24,25
All of these observations are consistent with a chelated transition state giving rise to L-ido selectivity.
Our results can also be explained in terms of chelated (with F-alkylmagnesium bromide; Scheme 3)
or non-chelated (with F-alkyl TMS) transition states and have not to be distinguished from this point
of view. What is noteworthy is that the stereoselectivity with fluorinated reagents is higher than with
non-fluorinated ones for both magnesium and silicon reagents. We have obtained a quasi complete L-
ido selectivity with the magnesium reagent without needing to add further chelating Lewis acid. On the
other hand, the selectivity of the addition of the non-chelating TFMTMS or F-alkyl TMS is similar to
or better than that of chelating non-fluorinated alkylmagnesium reagents. Hence, we have to consider
further stereoelectronic interactions due to the presence of fluorine atoms. In the chelated transition
state (F-alkylmagnesium), the usual steric hindrance favours the exo-face attack, moreover the endo-face
attack is inhibited by electronic hindrance between the oxygen-rich endo-face and the fluorine atoms. To
explain the stereoselectivity observed in absence of chelation (F-alkyl TMS) we propose an empirical
transition state model depicted in Scheme 3, different to the classical Felkin–Anh model which would

S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
219
give reversed stereoselectivity. In such a model, the increased electronic interaction between the carbonyl
oxygen and the heterocyclic oxygen is balanced by avoiding a strong interaction between the entering F-
alkyl group and the alkoxy group on C-3. Another point to take into account is the bulkiness of the actual
nucleophilic reagent: the ‘RF−’ is in fact delivered by a hypervalent fluorosilicon intermediate13 more
−
sterically demanding than a naked RF (which would be unstable due to β- or -α-elimination). Hence,
both electronic and steric factors would control the stereochemical outcome of the RF–TMS reagents.
Scheme 3.
2.2. Stereoselectivity of the F-alkylation of the 3-oxo-derivative 3
A general feature of nucleophilic attack on 3-oxo-glucose and, more generally, to corresponding
derivatives with an unsaturated sp2 C-3, is its high preference for the β-face, due to steric interactions
with the substituent at C-2.26 It is noteworthy that such a high stereoselectivity was observed with F-
alkyl nucleophiles only in the F-alkylsilane series, whereas the magnesium reagents led to an important
amount of the epimeric D-glucose derivative. Thus, in contrast to the reactions with the ‘pentodialdo’
derivatives, if a chelation of magnesium occurred, it would allow an α-attack and counteract the steric
strain.
Some comparisons with the reaction of classical magnesium reagents may be of interest. Non-bulky
reagents like methyl-, phenyl- or vinylmagnesium bromide gave a completely stereoselective β-face
addition with good yields.27 As soon as a β-hydrogen is available on the reagent, poor yields of addition
were obtained and the reduction of the carbonyl group leading to D-allose and D-glucose competes. The
yield of addition as well as the β-stereoselectivity of reduction are increased if magnesium bromide
is added to the medium and if the reaction is carried out at low temperature.28 Thus it seems that the
latter conditions induce a ‘protection’ against hydride transfer from the α-face, probably by its selective
complexation with magnesium bromide. We can assume that, in the absence of a possible competitive
reduction, a similar complexation of the F-alkylmagnesium reagent allows an intramolecular F-alkyl
group transfer from the α-face.
Even if a more satisfactory interpretation cannot be given, it is noteworthy that, for the first time,
without any additional salt, a substantial amount of the unusual adduct epimer, resulting from an α-
addition was isolated. Hence, as for the ‘pentodialdo’ derivatives, the addition of F-alkylmagnesium
reagents to 3-oxo-glucose derivative follows a particular behaviour compared to the hydrogenated
reagents.
3. Conclusion
Besides the synthesis and characterization of new C-F-alkylated carbohydrate derivatives, this study
emphasizes the stereochemical course of nucleophilic F-alkylation compared to alkylation. The stereo-
chemistry depends strongly on the nature of the counter metal. In particular, the results highlight the

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complete stereoselectivity of addition of F-alkylmagnesium reagents on pentodialdose, due to the usual
chelated transition state and stereoelectronic effect of the F-alkyl chain. Even with F-alkylsilanes, where
chelation may not be invoked, the stereoselectivity is higher than that usually observed with non-
fluorinated magnesium reagents. The F-alkyl nucleophiles also exhibit a particular character toward the
addition on the 3-oxo-glucose derivative, where complete stereoselectivity is observed, here, with silane
reagents, and where the chelated magnesium species counteracts the β-face preference. Deprotection of
the long F-alkyl chain compounds and the study of their amphiphilic properties will be reported in a
forthcoming paper.
4. Experimental section
4.1. General methods
All reactions were performed under a constant flow of dry argon. Commercial dichloromethane (Fluka
puriss) and ether (SDS) were used without further purification. Merck silica gel F254 (0.2 nm) was used
for TLC plates, detection being carried out by spraying with an alcoholic solution of phosphomolybdic
acid, followed by heating. Flash column chromatography was performed on silica gel Merck Art. 9385
Kieselgel 60 (0.04–0.063 µm). Melting points were determined with a Buchi apparatus. IR spectra were
recorded with an IRTM plus MIDAC spectrophotometer and are expressed in cm−1. NMR spectra were
1
recorded on a Brücker AC 250 spectrometer (250 MHz for H, 62.5 MHz for 13C and 235.36 MHz
for 19F). Chemical shifts are expressed in parts per million from TMS (1H and 13C) or CFCl3 as an
internal reference. Coupling constants are in Hz and splitting pattern abbreviations are: s, singlet; d,
doublet; t, triplet; q, quartet; m, multiplet. Optical rotations were determined with a Perkin–Elmer 241
polarimeter. Elemental analyses were performed with a Perkin–Elmer CHN 2400 apparatus. Mass spectra
were recorded on a Fison VG Autospec spectrometer.
4.2. F-Alkylation with RFSiMe3 — general procedure
The carbonylated compound (2 to 10 mmol) was dissolved in anhydrous dichloromethane (5
mL/mmol) and the reaction was cooled to 0°C. Then, TFMTMS or C4F9SiMe3 (1.1 equiv.) and a catalytic
amount of n-tetrabutylammonium difluorotriphenylstannate were added. The reaction was warmed to
room temperature and stirred until completion of the reaction. The reaction mixture was treated with
a 2 M aqueous HCl solution (reaction of 1 and 2) or the crude product in methanol was treated with
one equivalent of TBAF (reaction of 3). After partition between aqueous NH4Cl and dichloromethane,
the organic layer was dried over MgSO4, filtered and the solvent was evaporated. The crude product
was analyzed by NMR to determine the epimers proportions (see Table 1). Separation of the epimers or
purification by flash chromatography yielded the F-alkylated compounds.
4.3. Perfluoroalkylation with RFMgBr — general procedure
To a solution of perfluoroalkyl iodide (1.2 equiv.) in ether (3 mL/mmol) cooled to −45°C and protected
from light was added dropwise ethylmagnesium bromide (1.2 equiv.). The reaction was stirred at −45°C
for 0.5 h. The carbonylated compound (dehydrated by azeotropic distillation with toluene just before
use) (2 to 10 mmol, 1 equiv.), was dissolved in ether (2 mL/mmol) and added dropwise to the reaction
mixture. The reaction temperature was left to rise slowly to −10°C. After 2 h, the reaction was washed

S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
221
with a saturated solution of ammonium chloride (2×20 mL) and the aqueous layer was extracted with
ether (2×20 mL). The organic layer was dried over MgSO4, filtered and the solvent was evaporated. The
perfluoroalkylated compound was purified (separated) by flash chromatography.
4.4. 3-O-Benzyl-6-deoxy-6,6,6-trifluoro-1,2-O-isopropylidene-β-L-ido- and -α-D-glucofuranose 4 and
5
Conditions A: yield 1.2 g, 95% (4/5=80/20). Chromatography (petroleum ether/CH2Cl2 50/50).
4: oil. [α]20D=−29.5 (c 0.48, CHCl3). [Lit. [α]23D=−31.0 (c 0.74, CHCl3).] IR (film): 3462; 2997;
1265; 1128. MS (EI) m/z: 348 (M+•, 1); 333 (5); 290 (24); 128 (32); 91 (100); 85 (94); 65 (56); 59 (70).
1H NMR (CDCl3) δ: 1.32 (s, 3H, CH3); 1.48 (s, 3H, CH3); 3.28 (s, 1H, OH); 4.07 (d, 1H, J=3.0 Hz, H-3);
4.35 (m, 2H, H-4, H-5); 4.51 (d, 1H, JAB=11.4 Hz, CH2–Ph); 4.64 (d, 1H, J2,1=3.8 Hz, H-2); 4.68 (d, 1H,
J
AB=11.4 Hz, CH2–Ph); 5.98 (d, 1H, J1,2=3.8 Hz, H-1); 7.32–7.41 (m, 5H, Ph). 1H NMR (C6D6) δ: 1.09
(s, 3H, CH3); 1.33 (s, 3H, CH3); 3.49 (s, 1H, OH); 3.80 (d, 1H, J=3.5 Hz, H-3); 4.04 (d, 1H, JAB=11.4
Hz, CH2–Ph); 4.15 (d, 1H, JAB=11.4 Hz, CH2–Ph); 4.26 (d, 1H, J2,1=3.8 Hz, H-2); 4.39 (m, 1H, H-5);
4.45 (dd, 1H, J4,5=5.3 Hz, J4,3=3.4 Hz, H-4); 5.76 (d, 1H, J1,2=3.8 Hz, H-1); 7.10–7.14 (m, 5H, Ph). 13
C
NMR (CDCl3) δ: 26.2 (CH3); 26.7 (CH3); 68.4 (q, 2JC,F=31.5 Hz, C-5); 72.2 (CH2–Ph); 76.4 (C-4); 81.8
(C-2); 82.7 (C-3); 104.9 (C-1); 112.4 (Cq isopropylidene); 124.0 (q, JC,F=281.6 Hz, CF3); 127.8–128.4
(C-o, C-m, C-p); 136.4 (C-ipso). 13C NMR (C6D6) δ: 68.8 (q, JC,F=29.5 Hz, C-5). 19F NMR (CDCl3)
δ: −77.88 (d, 3F, JF,H=7.6 Hz, CF3). Anal. calcd for C16H19O5F3 (348.34): C, 55.17; H, 5.46. Found: C,
55.09; H, 5.29.
5: m.p. 97°C (petroleum ether); [α]20D=−38.6 (c 0.12, CHCl3). [Lit. [α]23D=−37.6 (c 1.00, CHCl3)].
1H NMR (CDCl3) δ: 1.26 (s, 3H, CH3); 1.43 (s, 3H, CH3); 4.16 (d, 1H, J=8.0 Hz, OH); 4.18 (d, 1H, J=3.0
Hz, H-3); 4.24 (dd, 1H, J4,5=4.6 Hz, J4,3=3.0 Hz, H-4); 4.34 (m, 1H, H-5); 4.48 (d, 1H, JAB=11.0 Hz,
CH2–Ph); 4.56 (d, 1H, J2,1=3.8 Hz, H-2); 4.60 (d, 1H, JAB=11.0 Hz, CH2–Ph); 5.94 (d, 1H, J1,2=3.8 Hz,
H-1); 7.25–7.40 (m, 5H, Ph). 1H NMR (C6D6) δ: 1.07 (s, 3H, CH3); 1.33 (s, 3H, CH3); 3.55 (d, 1H, J=6.6
Hz, OH); 4.06 (d, 1H, J3,4=2.8 Hz, H-3); 4.11 (d, 1H, JAB=11.5 Hz, CH2–Ph); 4.18 (d, 1H, JAB=11.5 Hz,
CH2–Ph); 4.24 (d, 1H, J2,1=3.7 Hz, H-2); 4.40 (m, 1H, H-5); 4.24 (dd, 1H, J4,5=5.8 Hz, J4,3=2.8 Hz, H-4);
5.81 (d, 1H, J1,2=3.7 Hz, H-1); 7.06–7.16 (m, 5H, Ph). 13C NMR (CDCl3) δ: 26.1 (CH3); 26.6 (CH3);
69.9 (q, 2JC,F=30.0 Hz, C-5); 72.7 (CH2–Ph); 75.4 (C-4); 81.5 (C-2); 83.8 (C-3); 104.9 (C-1); 112.2 (Cq
isopropylidene); 124.5 (q, J=283.0 Hz, CF3); 128.1–128.8 (C-o, C-m, C-p); 136.0 (C-ipso). 13C NMR
(C6D6) δ: 69,8 (q, JC,F=30.8 Hz, C-5). 19F NMR (CDCl3) δ: −77.63 (d, 3F, JF,H=7.6 Hz, CF3).
4.5. 3-O-Allyl-6-deoxy-6,6,6-trifluoro-1,2-O-isopropylidene-β-L-ido- and -α-D-glucofuranose 6 and 7
Conditions A: yield 0.65 g, 98% (6/7=88/12). Chromatography (petroleum ether/EtOAc 90/10).
6: oil. [α]18D=−30.0 (c 1.12, CHCl3). IR (film): 3462; 3086; 2997; 1379; 1140; 1028. MS (EI) m/z:
299 (M+1, 20); 283 (100); 241 (23); 113 (33); 85 (40); 59 (42). 1H NMR (C6D6) δ: 1.12 (s, 3H, CH3);
1.32 (s, 3H, CH3); 3.10 (s, 1H, OH); 3.65 (ddt, 1H, J=12.6 Hz, J=6.1 Hz, J=1.1 Hz, H-α allyl); 3.75 (d,
1H, J3,4=3.4 Hz, H-3); 3.82 (ddt, 1H, J=12.6 Hz, J=5.3 Hz, J=1.1 Hz, H-α allyl); 4.21 (m, 1H, H-5); 4.26
(dd, 1H, J4,5=5.3 Hz, J3,4=3.4 Hz, H-4); 4.30 (d, 1H, J2,1=3.8 Hz, H-2); 5.06 (m, 2H, H-γ allyl); 5.63
(ddt, 1H, J=16.0 Hz, J=11.0 Hz, J=5.7 Hz, H-β allyl); 5.72 (d, 1H, J1,2=3.8 Hz, H-1). 13C NMR (C6D6)
δ: 26.3 (CH3); 26.9 (CH3); 68.7 (q, 2JC,F=31.0 Hz, C-5); 71.2 (C-α); 76.8 (C-4); 82.4 (C-2); 82.9 (C-3);
105.2 (C-1); 112.6 (Cq isopropylidene); 118.2 (C-γ); 124.4 (q, J=281.6 Hz, CF3); 133.3 (C-β). 19F NMR
(C6D6) δ: −77.95 (d, 3F, JF,H=6.5 Hz, CF3). Anal. calcd for C12H17O5F3 (298.25): C, 48.32; H, 5.70.
Found: C, 48.38; H, 5.86.

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1
7: paste. H NMR (CDCl3) δ: 1.26 (s, 3H, CH3); 1.41 (s, 3H, CH3); 3.97 (ddt, 1H, J=12.0 Hz, J=6.1
Hz, J=1.4 Hz, H-α allyl); 4.07–4.15 (m, 3H, OH, H-3, H-α allyl); 4.21 (m, 1H, H-4); 4.34 (m, 1H,
H-5); 4.51 (d, 1H, J2,1=3.8 Hz, H-2); 5.20 (m, 2H, H-γ allyl); 5.82 (ddt, 1H, J=16.0 Hz, J=11.0 Hz,
J=5.7 Hz, H-β allyl); 5.93 (d, 1H, J1,2=3.8 Hz, H-1). 1H NMR (C6D6) δ: 1.07 (s, 3H, CH3); 1.33 (s, 3H,
CH3); 3.44–3.69 (m, 3H, OH, H-α allyl); 3.97 (d, 1H, J3,4=2.8 Hz, H-3); 3.97 (d, 1H, J2,1=3.7 Hz, H-2);
4.27–4.44 (m, 2H, H-4, H-5); 5.20 (m, 2H, H-γ allyl); 5.55 (m, 1H, H-β allyl); 5.80 (d, 1H, J1,2=3.7
Hz, H-1). 13C NMR (CDCl3) δ: 26.1 (CH3); 26.6 (CH3); 70.1 (q, 2JC,F=31.0 Hz, C-5); 71.3 (C-α); 75.4
(C-4); 81.7 (C-2); 83.6 (C-3); 104.8 (C-1); 112.1 (Cq isopropylidene); 122.2 (C-γ); 124.4 (q, J=281.0
Hz, CF3); 132.7 (C-β). 13C NMR (C6D6) δ: 70.3 (dd, JC,F=31.0 Hz, C-5). 19F NMR (CDCl3) δ: −77.88
(d, 3F, JF,H=7.6 Hz, CF3).
4.6. 3-O-Benzyl-6-deoxy-6,6-difluoro-6-C-perfluoropropyl-1,2-O-isopropylidene-β-L-ido- and -α-D-
glucofuranose 8a and 9a
Conditions A: yield 0.42 g, 65% (8a/9a=85/15). Conditions B: yield 2.91 g, 64% (8a/9a=>95/<5).
Chromatography (petroleum ether/EtOAc 85/15).
8a: white solid: m.p. 60°C. [α]20D=−2.6 (c 1.6, CHCl3). IR (KBr): 3462; 2967; 1228; 1064; 1028;
864. MS (EI) m/z: 498 (M+•, 8); 483 (100); 440 (43); 423 (32); 333 (38); 249 (34); 149 (28); 129 (77);
1
113 (27). H NMR (C6D6) δ: 1.07 (s, 3H, CH3); 1.30 (s, 3H, CH3); 3.31 (s, 1H, OH); 3.77 (m, 1H, H-
3); 3.99 (d, 1H, JAB=11.8 Hz, CH2–Ph); 4.14 (d, 1H, JAB=11.8 Hz, CH2–Ph); 4.22 (d, 1H, J2,1=3.4 Hz,
H-2); 4.52 (m, 2H, H-4, H-5); 5.70 (d, 1H, J1,2=3.4 Hz, H-1); 7.03–7.12 (m, 5H, Ph). 13C NMR (C6D6)
δ: 26.3 (CH3); 26.8 (CH3); 67.8 (dd, JC,F=29.0 Hz, JC,F=21.0 Hz, C-5); 72.2 (OCH2); 76.4 (C-4); 82.4
(C-2); 83.2 (C-3); 105.2 (C-1); 112.5 (Cq isopropylidene); 127.6–128.7 (C-o, C-m, C-p); 137.2 (C-ipso).
19F NMR (C6D6) δ: −81.11 (t, 3F, J=10.0 Hz, CF3); −119.61 (dm, 1F, JAB=278.5 Hz, CFa); −122.25
(dm, 1F, JAB=290.0 Hz, CFb); −123.14 (dm, 1F, JAB=290.0 Hz, CFb0); −125.23 (dm, 1F, JAB=278.5 Hz,
CFc); −125.90 (dm, 1F, JAB=278.5 Hz, CFa0); −127.00 (dm, 1F, JAB=278.5 Hz, CFc0). Anal. calcd for
C19H19O5F9 (498.34): C, 45.82; H, 3.84. Found: C, 46.08; H, 3.97.
9a: 1H NMR (CDCl3) δ: 1.33 (s, 3H, CH3); 1.49 (s, 3H, CH3); 4.28 (m, 2H, OH, H-3); 4.38 (m, 1H,
H-5); 4.56 (d, 1H, JAB=11.0 Hz, CH2–Ph); 4.65 (m, 2H, H-2, H-4); 4.68 (d, 1H, JAB=11.0 Hz, CH2–Ph);
6.02 (d, 1H, J1,2=3.8 Hz, H-1); 7.27–7.37 (m, 5H, Ph). 1H NMR (C6D6) δ: 1.08 (s, 3H, CH3); 1.35 (s, 3H,
CH3); 4.05 (d, 1H, JAB=11.3 Hz, CH2–Ph); 4.09 (m, 2H, OH, H-3); 4.12 (d, 1H, JAB=11.3 Hz, CH2–Ph);
4.23 (d, 1H, J2,1=3.8 Hz, H-2); 4.49 (ddd, 1H, J=4.9 Hz, J=3.2 Hz, J=1.8 Hz, H-4); 4.73 (m, 1H, H-5);
5.80 (d, 1H, J1,2=3.8 Hz, H-1); 7.03–7.18 (m, 5H, Ph). 13C NMR (CDCl3) δ: 26.1 (CH3); 26.6 (CH3);
69.8 (dd, JC,F=25.6 Hz, JC,F=21.7 Hz, C-5); 72.8 (OCH2); 74.8 (C-4); 81.8 (C-2); 84.7 (C-3); 104.6 (C-
1); 112.1 (Cq isopropylidene); 127.9–128.8 (C-o, C-m, C-p); 135.8 (C-ipso). 13C NMR (C6D6) δ: 70.0
(dd, JC,F=25.6 Hz, JC,F=21.6 Hz, C-5). 19F NMR (CDCl3) δ: −81.39 (t, 3F, J=9.5 Hz, CF3); −120.17
(dm, 1F, JAB=282.3 Hz, CFa); −122.81 (dm, 1F, JAB=297.5 Hz, CFb); −123.67 (dm, 1F, JAB=297.5 Hz,
CFb0); −125.63 (dm, 1F, JAB=297.5 Hz, CFc); −126.56 (dm, 1F, JAB=282.3 Hz, CFa0); −127.62 (dm,
1F, JAB=297.5 Hz, CFc0).
4.7. 3-O-Benzyl-6-deoxy-6,6-difluoro-6-C-perfluoropentyl-1,2-O-isopropylidene-β-L-idofuranose 8b
Conditions B: yield 0.53 g, 57%. Chromatography (petroleum ether/EtOAc 85/15).
White solid: m.p. 62°C. [α]19D=−21.3 (c 0.64, CHCl3). IR (KBr): 3462; 2961; 1454; 1240; 1078. MS
1
(EI) m/z: 598 (M+•, 5); 181 (67); 149 (98); 92 (81); 91 (100); 59 (39). H NMR (CDCl3) δ: 1.25 (s,
3H, CH3); 1.41 (s, 3H, CH3); 3.26 (s, 1H, OH); 4.00 (m, 1H, H-3); 4.43 (d, 1H, JAB=11.4 Hz, CH2–Ph);

S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
223
4.44 (m, 2H, H-4, H-5); 4.57 (d, 1H, J2,1=3.8 Hz, H-2); 4.61 (d, 1H, JAB=11.4 Hz, CH2–Ph); 5.99 (d,
1H, J1,2=3.8 Hz, H-1); 7.20–7.30 (m, 5H, Ph). 13C NMR (CDCl3) δ: 26.2 (CH3); 26.8 (CH3); 67.6 (dd,
2JC,F=27.6 Hz, 2JC,F=21.7 Hz, C-5); 72.3 (OCH2); 75.7 (C-4); 81.9 (C-2); 83.1 (C-3); 104.9 (C-1); 112.5
(Cq isopropylidene); 127.9–128.7 (C-o, C-m, C-p); 135.1 (C-ipso). 19F NMR (CDCl3) δ: −81.11 (t, 3F,
J=9.8 Hz, CF3); −112.59 (dm, 1F, JAB=282.0 Hz, CFa); −121.76 (m, 3F, CF2b, CFc); −122.16 (m, 1F,
CFc0); −122.54 (m, 1F, CFd); −122.86 (m, 1F, CFd0); −125.60 (dm, 1F, JAB=282.0 Hz, CFa0); −126.25
(dm, 1F, JAB=286.9 Hz, CFe); −127.25 (dm, 1F, JAB=286.9 Hz, CFe0). Anal. calcd for C21H19O5F13
(598.36): C, 42.14; H, 3.17. Found: C, 42.23; H, 3.29.
4.8. 3-O-Allyl-6-deoxy-6,6-difluoro-6-C-perfluoropropyl-1,2-O-isopropylidene-β-L-idofuranose 10a
Conditions B: yield 1.6 g, 68%. Chromatography (petroleum ether/EtOAc 80/20).
Syrup. [α]20D=−24.0 (c 0.19, CHCl3). IR (film): 3474; 2997; 2936; 1228; 1028. MS (EI) m/z: 448
(M+•, 7); 433 (97); 199 (33); 113 (100); 85 (65). 1H NMR (C6D6) δ: 1.11 (s, 3H, CH3); 1.35 (s, 3H, CH3);
3.39 (s, 1H, OH); 3.50 (dt, 1H, JAB=14.0 Hz, J=5.7 Hz, J=1.3 Hz, –OCH2–); 3.66 (dt, 1H, JAB=11.3 Hz,
J=5.3 Hz, J=1.3 Hz, –OCH2–); 3.74 (t, 1H, J=2.7 Hz, H-3); 4.22 (d, 1H, J2,1=3.7 Hz, H-2); 4.53–4.65 (m,
2H, H-4, H-5); 4.94–5.10 (m, 2H,=CH2); 5.59 (ddt, 1H, J=17.0 Hz, J=11.5 Hz, J=5.7 Hz, –CH_); 5.74 (d,
1H, J1,2=3.7 Hz, H-1). 13C NMR (C6D6) δ: 26.3 (CH3); 26.9 (CH3); 68.0 (dd, 2JC,F=29.0 Hz, 2JC,F=22.0
Hz, C-5); 71.0 (C-α); 76.6 (C-4); 82.6 (C-2); 83.2 (C-3); 105.2 (C-1); 112.5 (Cq isopropylidene); 117.5
(C-γ); 133.7 (C-β). 19F NMR (C6D6) δ: −81.42 (t, 3F, J=11.4 Hz, CF3); −120.36 (dm, 1F, JAB=283.0
Hz, CFa); −126.40 (dm, 1F, JAB=283.0 Hz, CFa0); −123.39 (m, 2F, CF2b); −125.70 (dm, 1F, JAB=290.0
Hz, CFc); −127.40 (dm, 1F, JAB=290.0 Hz, CFc0). Anal. calcd for C15H17O5F9 (448.28): C, 40.17; H,
3.79; Found: C, 40.28; H, 3.82.
4.9. 3-O-Allyl-6-deoxy-6,6-difluoro-6-C-perfluoropentyl-1,2-O-isopropylidene-β-L-idofuranose 10b
Conditions B: yield 1.17 g, 60%. Chromatography (petroleum ether/EtOAc 80/20).
Syrup. [α]24D=−36.0 (c 0.23, CHCl3). IR (film): 3462; 2997; 2936; 1240; 1203; 1028. MS (EI) m/z:
1
548 (M+•, 16); 533 (91); 433 (37); 199 (61); 133 (100); 85 (84); 59 (70). H NMR (C6D6) δ: 1.10 (s,
3H, CH3); 1.35 (s, 3H, CH3); 3.17 (d, 1H, J=2.4 Hz, OH); 3.46 (dt, 1H, JAB=12.7 Hz, J=5.3 Hz, J=1.3
Hz, –OCH2–); 3.63 (dt, 1H, JAB=12.7 Hz, J=4.4 Hz, J=1.3 Hz, –OCH2–); 3.72 (m, 1H, H-3); 4.18 (d,
1H, J2,1=3.6 Hz, H-2); 4.56 (m, 1H, H-4); 4.60 (m, 1H, H-5); 5.01 (ddt, 2H, Jtrans=17.0 Hz, Jcis=10.6 Hz,
J=1.6 Hz, =CH2); 5.55 (ddt, 1H, J=17.0 Hz, J=10.6 Hz, J=5.5 Hz, –CH_); 5.71 (d, 1H, J1,2=3.6 Hz, H-1).
13C NMR (C6D6) δ: 26.2 (CH3); 26.8 (CH3); 67.6 (dd, 2JC,F=29.0 Hz, 2JC,F=22.0 Hz, C-5); 71.2 (C-α);
75.9 (C-4); 82.1 (C-2); 83.0 (C-3); 104.9 (C-1); 112.5 (Cq isopropylidene); 118.5 (C-γ); 133.0 (C-β).
19F NMR δ: −81.34 (t, 3F, J=10.0 Hz, CF3); −120.25 (dm, 1F, JAB=283.0 Hz, CFa); −122.35 (m, 3F,
CF2b, CFc); −122.67 (m, 1F, CFc0); −122.97 (m, 1F, CFd); −123.77 (m, 1F, CFd0); −126.06 (dm, 1F,
J
AB=290.0 Hz, CFe); −126.07 (dm, 1F, JAB=283.0 Hz, CFa0); −127.07 (dm, 1F, JAB=290.0 Hz, CFe0).
Anal. calcd for C17H17O5F13 (548.30): C, 37.22; H, 3.10. Found: C, 37.59; H, 3.10.
4.10. 3-C-Trifluoromethyl-1,2:5,6-di-O-isopropylidene-α-D-allofuranose 12
Conditions A: yield 3.4 g, 88%. Chromatography (petroleum ether/EtOAc 80/20).
White solid: m.p. 76°C. [α]20D=+23.0 (c 1.8, CHCl3) IR (KBr): 3374; 2986; 1215; 1153; 1014; 877.
MS (EI) m/z: 313 (100); 195 (22); 131 (30); 101 (96); 69 (39); 59 (68). 1H NMR (CDCl3) δ: 1.36 (s, 3H,
0
CH3); 1.39 (s, 3H, CH3); 1.45 (s, 3H, CH3); 1.61 (s, 3H, CH3); 3.31 (s, 1H, OH); 3.94 (dd, 1H, J6,6 =8.8

224
S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
Hz, J6,5=5.3 Hz, H-6); 4.00 (d, 1H, J4,3=2.3 Hz, H-4); 4.11 (dd, 1H, J6 ,6=8.8 Hz, J6 ,5=6.1 Hz, H-60);
0
0
4.34 (m, 1H, H-5); 4.60 (d, 1H, J2,1=3.8 Hz, H-2); 5.83 (d, 1H, J1,2=3.8 Hz, H-1). 13C NMR (CDCl3) δ:
26.1 (CH3); 26.8 (3×CH3); 67.2 (C-6); 72.8 (C-5); 79.1 (C-2); 80.1 (q, 2JC,F=28.0 Hz, C-3); 81.4 (C-4);
2
104.0 (C-1); 109.8 (Cq isopropylidene); 113.8 (Cq isopropylidene); 124.2 (q, JC,F=285.0 Hz, CF3). 19
F
NMR (CDCl3) δ: −76.25 (s, 3F, CF3). Anal. calcd for C13H19O6F3 (328.28): C, 47.56; H, 5.79. Found:
C, 47.44; H, 5.54.
4.11. 3-C-Perfluorobutyl-1,2:5,6-di-O-isopropylidene-α-D-allo- and -α-D-glucofuranose 13a and 14a
Conditions A: yield 0.26 g, 70% (13a/14a=100/0). Conditions B: yield 2.34 g, 68% (13a/14a=78/22).
Chromatography (petroleum ether/EtOAc 90/10).
13a: white solid: m.p. 118°C (petroleum ether). [α]22D=+21.9 (c 0.47, CHCl3). IR (KBr): 3427; 2997;
1215; 1128; 1039; 827. MS (EI) m/z: 463 (100); 405 (24); 345 (22); 287 (18); 131 (73). 1H NMR (CDCl3)
δ: 1.38 (s, 3H, CH3); 1.43 (s, 3H, CH3); 1.47 (s, 3H, CH3); 1.63 (s, 3H, CH3); 3.41 (s, 1H, OH); 3.98 (dd,
0
0
0
1H, J6,6 =8.8 Hz, J6,5=5.3 Hz, H-6); 4.06 (d, 1H, J4,5=7.3 Hz, H-4); 4.13 (dd, 1H, J6 ,6=8.8 Hz, J6 ,5=6.1
Hz, H-60); 4.56 (m, 1H, H-5); 4.76 (dd, 1H, J2,1=4.2 Hz, J2,F=1.1 Hz, H-2); 5.71 (d, 1H, J1,2=4.2 Hz,
H-1). 13C NMR (CDCl3) δ: 25.1 (CH3); 26.4 (CH3); 26.6 (CH3); 26.7 (CH3); 67.0 (C-6); 72.9 (d, J=5.9
Hz, C-5); 78.3 (m, C-2); 81.0 (t, JC,F=25.6 Hz, C-3); 84.3 (C-4); 104.2 (C-1); 109.7 (Cq isopropylidene);
113.8 (Cq isopropylidene). 19F NMR (CDCl3) δ: −81.23 (t, 3F, J=11.5 Hz, CF3); −114.15 (dq, 1F,
J
AB=293.7 Hz, J=15.3 Hz, CFa); −117.89 (dm, 1F, JAB=297.6 Hz, CFb); −120.10 (dq, 1F, JAB=293.7
Hz, J=15.3 Hz, CFa0); −120.80 (dm, 1F, JAB=297.6 Hz, CFb0); −126.08 (dm, 1F, JAB=293.7 Hz, CFc);
−127.05 (dm, 1F, JAB=293.7 Hz, CFc0). Anal. calcd for C16H19O6F9 (478.31): C, 40.17; H, 4.00. Found:
C, 40.57; H, 3.84.
14a: oil. 1H NMR (CDCl3) δ: 1.34 (s, 3H, CH3); 1.36 (s, 3H, CH3); 1.46 (s, 3H, CH3); 1.52 (s, 3H,
CH3); 4.00 (dd, J6,6 =8.8 Hz, J6,5=7.6 Hz, H-6); 4.10 (dd, J6 ,6=8.8 Hz, J6 ,5=7.6 Hz, H-60); 4.47 (d, 1H,
0
0
0
J
4,5=3.4 Hz, H-4); 4.54 (m, 1H, H-5); 4.60 (m, 1H, H-2); 4.63 (s, 1H, OH); 5.71 (d, 1H, J1,2=3.4 Hz,
H-1). 13C NMR (CDCl3) δ: 24.6 (CH3); 25.9 (CH3); 26.5 (CH3); 26.8 (CH3); 66.4 (C-6); 74.9 (C-5);
78.4 (C-2); 82.5 (t, JC,F=23.4 Hz, C-3); 85.1 (C-4); 104.2 (C-1); 110.5 (Cq isopropylidene); 114.0 (Cq
isopropylidene). 19F NMR δ: −81.23 (t, 3F, J=10.5 Hz, CF3); −112.55 (m, 2F, CF2a); −119.67 (dm, 1F,
J
AB=293.7 Hz, CFb); −120.88 (dm, 1F, JAB=293.7 Hz, CFb0); −126.58 (m, 2F, CF2c).
4.12. 3-C-Perfluorohexyl-1,2:5,6-di-O-isopropylidene-α-D-allo- and -α-D-glucofuranose 13b and 14b
Conditions B: yield 2.5 g, 59% (13b/14b=73/27). Chromatography (petroleum ether/EtOAc 90/10).
13b: white solid: m.p. 123°C. [α]22D=+19.1 (c 0.83, CHCl3). IR (KBr): 3437; 2997; 1379; 1203; 1039;
864. MS (EI) m/z: 563 (81); 505 (19); 445 (13); 387 (18); 131 (100); 119 (100). 1H NMR (CDCl3) δ: 1.37
(s, 3H, CH3); 1.42 (s, 3H, CH3); 1.46 (s, 3H, CH3); 1.62 (s, 3H, CH3); 3.43 (s, 1H, OH); 3.94 (dd, 1H,
0
0
0
J6,6 =8.5 Hz, J6,5=4.9 Hz, H-6); 4.04 (d, 1H, J4,5=7.3 Hz, H-4); 4.09 (dd, 1H, J6 ,6=8.5 Hz, J6 ,5=6.1 Hz,
H-60); 4.50 (m, 1H, H-5); 4.73 (dd, 1H, J2,1=4.2 Hz, J2,F=1.8 Hz, H-2); 5.86 (d, 1H, J1,2=4.2 Hz, H-1).
13C NMR (CDCl3) δ: 25.1 (CH3); 26.4 (CH3); 26.6 (CH3); 26.7 (CH3); 67.0 (C-6); 72.9 (d, J=5.9 Hz, C-
5); 78.3 (m, C-2); 80.7 (t, JC,F=25.6 Hz, C-3); 84.3 (C-4); 104.2 (C-1); 109.7 (Cq isopropylidene); 113.8
(Cq isopropylidene). 19F NMR (CDCl3) δ: −81.33 (t, 3F, J=9.5 Hz, CF3); −113.75 (dq, 1F, JAB=289.9
Hz, J=15.3 Hz, CFa); −116.00 (dm, 1F, JAB=293.7 Hz, CFb); −119.00 (dm, 1F, JAB=289.9 Hz, CFa0);
−120.00 (dm, 1F, JAB=293.7 Hz, CFb0); −122.37 (m, 2F, CF2c); −123.03 (m, 2F, CF2d); −126.53 (m,
2F, CF2e). Anal. calcd for C18H19O6F13 (578.33): C, 37.28; H, 3.31. Found: C, 37.22; H, 2.96.

S. Lavaire et al. / Tetrahedron: Asymmetry 9 (1998) 213–226
225
14b: oil. [α]25D=+21.7 (c 0.59, CHCl3). 1H NMR (CDCl3) δ: 1.36 (s, 3H, CH3); 1.37 (s, 3H, CH3);
0
1.48 (s, 3H, CH3); 1.53 (s, 3H, CH3); 3.98 (dd, 1H, J6,6 =8.0 Hz, J6,5=7.2 Hz, H-6); 4.13 (t, 1H,
J
6 ,6=J6 ,5=8.0 Hz, H-60); 4.47 (d, 1H, J4,5=3.8 Hz, H-4); 4.54 (m, 1H, H-5); 4.60 (m, 1H, H-2); 4.66
0 0
(s, 1H, OH); 5.94 (d, 1H, J1,2=3.4 Hz, H-1). 13C NMR (CDCl3) δ: 24.6 (CH3); 25.9 (CH3); 26.6 (CH3);
26.9 (CH3); 66.4 (C-6); 75.0 (C-5); 78.3 (C-2); 82.6 (t, JC,F=23.6 Hz, C-3); 85.1 (C-4); 104.2 (C-1);
110.6 (Cq isopropylidene); 114.0 (Cq isopropylidene). 19F NMR (CDCl3) δ: −81.42 (t, 3F, J=9.6 Hz,
CF3); −111.99 (dm, 1F, JAB=288.0 Hz, CFa); −112.75 (dm, 1F, JAB=288.0 Hz, CFa0); −118.73 (dm, 1F,
J
AB=293.7 Hz, CFb); −119.91 (dm, 1F, JAB=293.7 Hz, CFb0); −122.29 (m, 2F, CF2c); −123.01 (m, 2F,
CF2d); −126.55 (m, 2F, CF2e).
Acknowledgements
We thank the ‘Conseil Général de la Marne’ for financial support and for a fellowship (S.L.), and H.
Baillia and S. Lanthony for NMR spectra and microanalyses.
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