Application of the triisobutylaluminum-promoted reductive rearrangement to sucrose-5-enes

Article abstract of DOI:10.1560/DJYX-KN0A-FGNW-TEQM

Carbohydrate-based vinyl acetals (5-hex-enopyranosides) undergo reductive rearrangement with triisobutylaluminum (TIBAL) to afford highly functionalized cyclohexanes in which both the aglycon and anomeric stereochemistry are retained. Here, we report the

Full text of DOI:10.1560/DJYX-KN0A-FGNW-TEQM

Application of the Triisobutylaluminum-Promoted Reductive Rearrangement to
Sucrose-5-enes
BÉRENGÈRE DU ROIZEL, ANA M. P. HENRIQUES, ALAN J. PEARCE, AND PIERRE SINAŸ*
École Normale Supérieure, Département de Chimie, associé au CNRS, 24 rue Lhomond, 75231 Paris Cédex 05, France
(Received 2 August 2000 and in revised form 19 Nov 2000)
Abstract. Carbohydrate-based vinyl acetals (5-hex-enopyranosides) undergo
reductive rearrangement with triisobutylaluminum (TIBAL) to afford highly
functionalized cyclohexanes in which both the aglycon and anomeric stereochemis-
try are retained. Here, we report the first application of this process to the rearrange-
ment of hex-5-enopyranosides of sucrose in which the interglycosidic oxygen atom
of the vinyl acetal system links the anomeric centers of both monosaccharide units.
The sucrose-derived 5-hex-enopyranoside 1 undergoes smooth reductive rearrange-
ment with TIBAL to afford the (1→2′) ether-linked pseudo-disaccharide 2 in 34%
yield. The rearrangement is accompanied by some loss of stereochemical integrity at
C-2′ due to a competitive exo-cleavage of the interglycosidic (O-C2′) bond, hence
diastereomers at C-2′ are also obtained in 12% yield. The 4-O-allyl-protected
sucrose-5-ene 3 is similarly transformed into the corresponding (1→2′) ether-linked
pseudo-disaccharide 4, illustrating the compatibility of the allyl group with the
TIBAL reaction conditions.
INTRODUCTION
This versatile TIBAL-promoted rearrangement has
The Lewis acid-promoted transformation of sugar-based also been applied to 5-hex-enopyranosides containing
vinyl acetals into carbocycles provides a direct approach different aglycon moieties including S-, Se-, and C-aryl
to the synthesis of highly functionalized enantio- glycosides.3 When applied to hex-5-enopyranosides 7, 9
merically pure cyclohexanes.1 We have developed an and 11, 13 containing sugar aglycons, this led to trans-
efficient methodology for the preparation of such cyclo- formation of the pyranose ring at the non-reducing end
hexanes by the reductive rearrangement of carbohydrate- of the disaccharide into a carbocycle affording (1→6)
based vinyl acetals using triisobutylaluminum (TIBAL) and (1→4) ether-linked pseudo-disaccharides4 8, 10 and
as the Lewis acid.2 Thus, 5-hex-enopyranosides such as 12, 14, respectively (Scheme 1), the latter of which was
5 undergo reductive rearrangement with TIBAL to af- subsequently transformed into a 5′a-carbadisaccharide.5
ford highly functionalized cyclohexanes such as 6, in Furthermore, tandem6 and cascade7 variants of the
which both the aglycon and anomeric stereochemistry
are retained (Scheme 1).
*Authortowhomcorrespondenceshouldbeaddressed. E-mail:
pierre.sinay@ens.fr
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318
Scheme 1. Typical examples of the TIBAL-promoted reductive rearrangement.
TIBAL-promoted rearrangement have been demonstrated The structure of 1 was confirmed by 13C NMR spectros-
for bis- and polyunsaturated systems, respectively.
copy, which showed clear signals for the exocyclic
As part of our program to evaluate the wider scope double bond (δ = 153.8, s, C-5 and 96.3, t, C-6). Simi-
and limitations of the TIBAL-promoted reductive rear- larly, iodide 17 underwent one-pot allylation-elimina-
rangement,8 we herein report the first application of this tion with NaH in DMF containing allyl bromide to give
process to the rearrangement of hex-5-enopyranosides the 4-O-allyl sucrose-5-ene 3 in 88% yield. The presence
(1 and 3) of sucrose, a non-reducing disaccharide. In of the exocyclic double bond in 3 was confirmed by 13C
contrast to previous systems, the interglycosidic oxygen NMR spectroscopy (δ = 154.1, s, C-5 and 96.1, t, C-6).
atom of the vinyl acetal system links the anomeric cen-
ters of both monosaccharide units.
Reaction of sucrose-5-ene 1 with excess TIBAL at
50 °C resulted in reductive rearrangement to afford the
expected (1→2′) ether-linked pseudo-disaccharides 18
(20%) and 19 (14%) (Scheme 3).a Quite unexpectedly
RESULTS AND DISCUSSION
Sucrose 15 was readily transformed into the sucrose-5- we isolated the corresponding epimers at C-2′, i.e., the
enes 1 and 3 using the synthesis summarized in Scheme (1→2′) ether-linked pseudo-disaccharides 20 (11%) and
2. Acetonation of sucrose afforded 4,6-isopropylidene- 21 (1%). The assignment of the anomeric configuration
sucrose,9 which was benzylated using benzyl bromide of the fructofuranoside linkage of the pseudo-disaccha-
and NaH in DMF, and subsequently hydrolyzed to af- rides was based on the characteristic shifts of the C-2′
ford the known 4,6-diol 16.10 Selective iodination of the signals in the 13C NMR spectra; C-2′ signals for α-
primary alcohol of 16 was achieved using Garegg and
Samuelsson’s conditions11 to afford iodide 17 in 93%
yield. Iodide 17 underwent smooth benzylation-elimi-
nation with NaH in DMF containing benzyl bromide to
aHigh Resolution Mass Spectrometry was performed on this
compound because there was not enough product to achieve
elemental analysis. The difference observed (-8,8 ppm) is low
afford the per-benzylated sucrose-5-ene 1 in 98% yield. enough to consider the sample "pure".
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319
Scheme 2. Preparation of sucrose-5-ene substrates 1 and 3 for TIBAL-promoted rearrangement. Reagents and Conditions: (i) 2-
methoxyprop-1-ene, cat PTSA, DMF, 70 °C, 2 h, 78%; (ii) NaH, BnBr, DMF, 56%; (iii) aq AcOH, acetone, 80 °C, 30 min, 83%;
(iv) Ph3P, I2, Im, PhMe, 70 °C, 93%; (v) NaH, BnBr, DMF, RT, 98%; (vi) NaH, 1-bromoprop-2-ene, DMF, RT, 88%.
fructofuranosides occur at 107–108 ppm and at 103–104 reasoned that direct TIBAL-promoted epimerization at
ppm for β-fructofuranosides.12
C-2′ was probably not occurring. We therefore con-
We first suspected that formation of the α-fructo- cluded that cleavage of the C2′-Oexo bond must occur
furanosides 20 and 21 might be due to a direct Lewis before or during the rearrangement step. This fact con-
acid-promoted epimerization of 18 and 19 occurring forms with the formation of the three major side-prod-
after the rearrangement step. Although this has not spe- ucts 22, 23,14 and 24 (Scheme 3), resulting from the
cifically been demonstrated for 18 and 19, no reaction cleavage of the interglycosidic bond (C2′-Oexo). These
1
was observed when octabenzyl sucrose13 was treated products were identified by a combination of H/
with excess TIBAL at 50 °C for 4 days, and we thus 13C NMR and mass spectrometry although the stereo-
Scheme 3. TIBAL-promoted reductive rearrangement of sucrose-5-enes 1 and 3.
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Scheme 4. Proposed mechanism for the TIBAL-promoted reductive rearrangement of sucrose-5-ene 1. The precise details of this
mechanism are not known.
chemistry of 22 and 24 has not been vigorously estab- accompanied by the corresponding epimers at C-2′ 29
lished. Hence, we tentatively propose the following and 30. This poor yield is due to the formation of side-
mechanism: coordination of the Lewis acid TIBAL to products resulting from competitive interglycosidic
the endocyclic oxygen atom of the pyranose ring leads bond cleavage and partial epimerization at C-2′, as ob-
to cleavage of the C1-Oendo bond, which is accompanied served in the previous case. However, the side-products
by cleavage of the C2′-Oexo bond, leading to formation were not isolated in this case. Although small quantities
of the fructofuranosyl oxycarbenium intermediate 25 of pure 27 and 28 were isolated by flash chromatogra-
and aluminum enolate 26. Carbocyclization of 26 and phy of the mixture, the workup was significantly simpli-
recombination with 25 lead to the formation of the fied by direct oxidation of the mixture with acetic anhy-
isolated products after in situ reduction of the intermedi- dride in DMSO to afford a mixture of ketone 31 as a
ate ketones with TIBAL. Thus, the recombination step major diastereomer in 57% yield, together with 18% of
accounts for the loss of stereochemical integrity ob- the C-2′ epimer (α-furanose) as calculated by integra-
served at C-2′ (Scheme 4). This mechanism implies that tion of proton 6-Ha: 2.87 (dd, 1 H, J6a,6b 15.0 Hz, J5,6a
carbocyclization of 26 leads to a single isomer at C-1, as 5.0 Hz) for this minor diastereomer.
previously observed for the regular rearrangement.2 It
First, the compatibility of the allyl protecting group
should also be noted that formation of 18 and 19 can with the TIBAL-promoted reaction conditions15 is sig-
equally be accounted for by the regular rearrangement nificant, as previously we have only reported rearrange-
mechanism without invoking interglycosidic bond ments of perbenzylated hex-5-enopyranosides. Second,
cleavage.
oxidation to the ketone 31 is advantageous, given that
Reaction of 4-O-allyl-sucrose-5-ene 3 with excess the ketone function is ideal for homologation to a carba-
TIBAL at RT also resulted in reductive rearrangement sugar.5 In this context, access to the free 4-OH group
to afford the desired (1→2′) ether-linked pseudo-disac- after removal of the allyl group might also prove useful
charides 27/28 (28%) as a 1:1 mixture (Scheme 3), in controlling the stereochemistry at C-5.16
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321
11.3 Hz, 1 H, CHPh), 4.76–4.62 (m, 7 H, 7 × CHPh), 4.58–
4.55 (m, 4 H, 3′-H, 3 × CHPh), 4.47 (t, 1 H, J3′,4′ = 4′,5′ 8.0 Hz, 4′-
H), 4.36 (d, 1 H, J 11.3 Hz, CHPh), 4.15 (ddd, 1 H, J4′,5′ 8.0 Hz,
J5′,6′b 5.0 Hz, J5′,6′a 4.0 Hz, 5′-H), 3.84–3.82 (m, 2 H, 3-H, 6′-
Ha), 3.81 (d, 1 H, J1′a,1′b 10.8 Hz, 1′-Ha), 3.74 (dd, 1 H, J6′a,6′b
10.6 Hz, J5′,6′b 5.0, 6′-Hb), 3.66 (d, J1′a,1′b 10.8 Hz, 1′-Hb), 3.52
(dt, 1 H, J4,5 9.3 Hz, J5,6a = 5,6b 3.0 Hz, 5-H), 3.46 (br t, 1 H, J3,4 = 4,5
9 Hz, 4-H), 3.42 (dd, 1 H, J2,3 9.6 Hz, J1,2 3.6 Hz, 2-H), 3.27
(dd, 1 H, J6a,6b 10.9 Hz, J5,6a 3.0 Hz, 6-Ha), 3.22 (dd, 1H, J6a,6b
10.9 Hz, J5,6b 3.0, 6-Hb), 2.30 (br s, 1 H, OH). 13C NMR
(CDCl3): δ= 138.6, 138.1, 138.0, 137.9, 137.9, 137.8 (6 × s, C-
arom. quat.), 128.5–127.4 (30 × d, Ph), 104.4 (C-2′), 89.1 (C-1),
83.7 (C-3′), 80.6 (C-4′), 80.4 (C-3), 79.5 (C-2), 79.1 (C-5′), 75.0
(t, CH2Ph), 73.5 (C-4), 73.4, 73.2, 73.1, 72.6 (4 × t, CH2Ph),
71.55 (C-1′), 71.5 (t, CH2Ph), 70.1 (C-6′), 68.4 (C-5), 9.9 (C-6).
MS (CI); m/z (%): 1010.8 (80) [MNH4+], 884.9 (100). C54H57IO10
(992.9): calcd C 65.32, H 5.79; found C 65.31, H 5.89.
CONCLUSIONS
This work extends the scope of the TIBAL-induced
rearrangement in carbohydrate chemistry:
1. This paper reports the first TIBAL-promoted reduc-
tive rearrangement of readily available sucrose-5-
enes (1 and 3) to highly functionalized (1→2′) ether-
linked pseudo-disaccharides (18, 19, 27, 28).
2. The rearrangement is accompanied by some loss of
stereochemical integrity at C-2′ due to cleavage of
the interglycosidic (O–C2′) bond, leading to forma-
tion of diastereomers at C-2′. This arises from the
unusual extended vinyl acetal system, in which the
interglycosidic oxygen atom of the vinyl acetal sys-
tem links the anomeric centers of both monosaccha-
ride units.
3. The successful rearrangement of the 4-O-allyl pro-
tected sucrose-5-ene 3 demonstrates the compatibility
of the allyl group with the TIBAL reaction condi-
tions.
4. Ketone 31 provides a potential intermediate for ho-
mologation to 5a-carba-sucrose.
Hepta-O-benzyl-2′-O-(6-deoxy-α-D-xylo-hex-5-enopyran-
osyl)-β-D-fructofuranoside (1). Sodium hydride (2.4 g,
60.0 mmol, 60% in mineral oil) was added to a stirred solution
of 17 (5.0 g, 5.0 mmol) in anhydrous DMF (100 mL) contain-
ing benzyl bromide (0.8 ml, 6.6 mmol) at room temperature.
After 22 h, TLC (EtOAc/cyclohexane, 5:1) indicated no start-
ing material (Rf 0.3) and product (Rf 0.4), and the reaction
mixture was cooled to 0 °C and methanol (10 mL) was added
dropwise. The solvent was removed in vacuo and the residue
was partitioned between DCM (200 mL) and brine (200 mL).
The aqueous layer was extracted with DCM (3 × 200 mL) and
the combined organic layers were dried (MgSO4), filtered, and
the solvent was removed in vacuo. The residue was purified by
flash chromatography (eluent gradient, 5–17% EtOAc in cy-
clohexane) to afford 1 (4.7 g, 98%), as a colorless oil. [α]D22 +6
(c 1.0 in CHCl3). 1H NMR (CDCl3): δ = 7.47–7.33 (m, 35 H,
arom. H), 5.86 (d, 1 H, J1,2 3.1 Hz, 1-H), 4.91–4.83 (m, 5 H, 6-
Ha, 2 × CH2Ph), 4.79–4.61 (m, 10 H, 6-Hb, 9 × CHPh), 4.59–
4.57 (br m, 1 H, 4′-H), 4.48 (d, 1 H, J 12.0 Hz, CHPh), 4.31–
4.26 (m, 2 H, 3′-H, 5′-H), 4.08–4.04 (m, 2 H, 3-H, 4-H), 3.90
(dt, 1 H, J6′a,6′b 10.1 Hz, J4′,6′a = 5′,6′a 3 Hz, 6′-Ha), 3.83 (d, 1 H,
J1′a,1′b 11.1 Hz, 1′-Ha), 3.79 (dt, 1 H, J6′a,6′b 10.1 Hz, J4′,6′b = 5′,6′b
1.8 Hz, 6′-Hb), 3.67–3.64 (m, 2 H, 2-H, 1′-Hb). 13C NMR
(CDCl3): δ= 153.8 (C-5), 138.6, 138.3, 138.15, 138.13, 138.1,
138.0, 137.8 (7 × s, C-arom. quat.), 128.4–127.5 (35 × d, Ph),
104.6 (C-2′), 96.3 (C-6), 91.4 (C-1), 83.8 (C-4′), 82.4 (C-3′),
80.2 (C-3), 79.8 (C-5′), 79.5 (C-4), 79.3 (C-2), 75.3, 74.0,
73.3, 73.2, 72.9, 72.6, 72.5 (7 × t, CH2Ph), 71.7 (C-6′), 70.5
(C-1′). MS (CI); m/z (%): 972.6 (100) [MNH4+]. C61H62O10
(955.2): calcd C 76.71, H 6.54; found C 76.60, H 6.72.
EXPERIMENTAL
General
Melting points: Büchi 510 apparatus and were uncorrected.
IR: Nicolet Impact 400D. Optical rotations: Perkin Elmer 241
digital polarimeter. MS: Nermag R10-10 spectrometer, C.I.
(ammonia). Elemental analyses: performed by Service
d′Analyse de l’Université Pierre et Marie Curie, Paris. NMR:
1
Brüker AM-400 (400 MHz and 100.6 MHz, for H and 13C,
respectively), TMS as internal standard. All NMR assign-
ments were supported by COSY and 1H-13C-correlation. TLC:
silica gel 60 F254 (Merck) and detection by charring with concd
H2SO4. Flash column chromatography: silica gel 60 (230–400
mesh, Merck).
1′,2,3,3′,4′,6′-Hepta-O-benzyl-6-deoxy-6-iodo-sucrose
(17). Triphenylphosphane (0.50 g, 1.92 mmol), imidazole
(0.26 g, 3.82 mmol), and iodine (0.49 g, 1.91 mmol) were
added to a stirred solution of 1′,2,3,3′,4′,6′-hexa-O-benzyl-
sucrose (16)10 (1.27 g, 1.44 mmol) in anhydrous toluene
(25 mL) at room temperature under argon. The mixture was
heated at 70 °C for 2.5 h, when TLC (Et2O/cyclohexane, 3:1)
indicated no starting material (Rf 0.3) and a major product (Rf
0.8). The reaction mixture was cooled to room temperature,
1′,3′,4′,6′-Tetra-O-benzyl-2′-O-[1D-(1,2,4,5/3)-2,3,4-tri-
and saturated sodium thiosulfate (20 mL) was added. After 15 O-benzyl-1,2,3,4,5-pentahydroxy-cyclohexyl]-β-D-
min, the aqueous layer was extracted with EtOAc (3 × 30 mL), fructofuranoside (18), 1′,3′,4′,6′-Tetra-O-benzyl-2′-O-[1D-
and combined extracts were dried (MgSO4), filtered, and the (1,2,4,5/3)-2,3,4-tri-O-benzyl-1,2,3,4,5-pentahydroxy-
solvent was removed in vacuo. The residue was purified by cyclohexyl]-α-D-fructofuranoside (20), 1′,3′,4′,6′-tetra-O-
flash chromatography (eluent gradient, 13–50% EtOAc in benzyl-2′-O-[1D-(1,2,4/3,5)-2,3,4-tri-O-benzyl-1,2,3,4,5-
cyclohexane) to afford 17 (1.18 g, 93%), as a colorless oil. pentahydroxy-cyclohexyl]-α-D-fructofuranoside (21),
[α]D22 +40 (c 1.0 in CHCl3). 1H NMR (CDCl3): δ = 7.42–7.33 1′,3′,4′,6′-tetra-O-benzyl-2′-O-[1D-(1,2,4/3,5)-2,3,4-tri-O-
(m, 30 H, arom. H), 5.99 (d, 1 H, J1,2 3.6 Hz, 1-H), 5.03 (d, J benzyl-1,2,3,4,5-pentahydroxy-cyclohexyl]-β-D -
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fructofuranoside (19). TIBAL (18.0 mL, 18.0 mmol, 1M in 2.31 (dt, J6a,6b 13.2 Hz, J1,6a = 5,6a 4.4 Hz, 6-Ha), 2.19 (br s, 1 H,
toluene) was added to a stirred solution of 1 (2.6 g, 2.7 mmol) OH), 1.31 (m, 1 H, 6-Hb). 13C NMR (CDCl3): δ= 138.9, 138.8,
in anhydrous toluene (90 mL) at room temperature under 138.6, 138.2, 138.2, 138.2, 137.9 (7 × s, C-arom. quat.),
argon. The reaction mixture was heated at 50 °C and after 5 h 128.5–127.2 (35 × d, Ph), 108.1 (C-2′), 88.5 (C-3′), 86.6 (C-4),
further TIBAL (15.0 mL, 15.0 mmol, 1M in toluene) was 83.0 (C-2), 81.4 (C-3), 79.9 (C-5′), 75.4, 75.4, 73.4, 73.2, 72.6,
added. After a further 2.5 h TLC (EtOAc/cyclohexane, 3:10) 72.0, 71.8 (7 × t, CH2Ph), 69.9 (C-6′), 68.9 (C-5), 68.4 (C-1′),
indicated no starting material (Rf 0.64) and four components 65.6 (C-1), 29.7 (C-6). MS (CI); m/z (%): 974.7 (100)
+
(Rf 0.34, 0.28, 0.25, and 0.20) as part of a complex mixture. [MNH4 ]. C61H64O10: calcd 974.4843 found 974.4835
The mixture was cooled to 0 °C and icewater (50 mL) was (–0.8 ppm) [MNH4+].
added. The mixture was filtered into a separatory funnel,
(19) (358 mg, 14%) : as a colorless oil. [α]D21 +33 (c 1.0 in
washing with EtOAc (50 mL), and the aqueous layer was CHCl3). 1H NMR (CDCl3): δ = 7.42–7.30 (m, 35 H, arom. H),
extracted with EtOAc (2 × 100 mL). Combined extracts were 5.02 (d, 1 H, J 11.5 Hz, CHPh), 4.88-4.50 (m, 13 H, 12 ×
dried (MgSO4), filtered, and the solvent was removed in CHPh, 1-H), 4.49 (d, 1 H, J3′,4′ 7.3 Hz, 3′-H), 4.43 (d, 1 H, J
vacuo. The residue was purified by flash chromatography 12.0 Hz, CHPh), 4.28 (dd, 1 H, J4′,5′ 7.8 Hz, J3′,4′ 7.3 Hz, 4′-H),
(eluent gradient, 10–50% EtOAc in cyclohexane) to afford by 4.10 (ddd, 1 H, J4′,5′ 7.8 Hz, J5′,6′a 4.7 Hz, J5′,6′b 3.0 Hz, 5′-H),
order of elution:
4.05–3.99 (m, 1 H, 5-H), 3.94 (t, 1 H, J2,3 = 3,4 9 Hz, 3-H), 3.78
(18) (512 mg, 20%), as a colorless oil. [α]D21 +24 (c 1.0 in (dd, 1 H, J6′a,6′b 10.6 Hz, J5′,6′b 3.0 Hz, 6′-Hb), 3.73 (d, 1 H, J1′a,1′b
CHCl3). 1H NMR (CDCl3): δ = 7.42–7.32 (m, 35 H, arom. H), 10.8 Hz, 1′-Hb), 3.69 (d, 1 H, J1′a,1′b 10.8 Hz, 1′-Ha), 3.65 (dd,
4.95–4.72 (m, 8 H, 8 × CHPh), 4.68 (br m, 1 H, 1-H), 4.62 (m, 1H, J6′a,6′b 10.6 Hz, J5′,6′a 4.7 Hz, 6′-Ha), 3.34 (dd, 1 H, J2,3 9 Hz,
4 H, 4 × CHPh), 4.49 (d, 1 H, J3′,4′ 7.5 Hz, 3′-H), 4.44 (d, 1 H, J1,2 2.8 Hz, 2-H), 3.32 (t, 1 H, J3,4 = 4,5 9 Hz, 4-H), 2.51 (dt, 1 H,
J 12.0 Hz, CHPh), 4.29 (d, 1 H, J 12.3 Hz, CHPh), 4.27 (dd, 1 J6a,6b 13.4 Hz, J1,6a = 5,6a 4.4 Hz, 6-Ha), 1.24 (br t, 1 H, J 12 Hz, 6-
H, J4′,5′ 8.3 Hz, J3′,4′ 7.5 Hz, 4′-H), 4.18 (t, 1 H, J2,3 = 3,4 9 Hz, 3- Hb). 13C NMR (CDCl3): δ = 138.8, 138.8, 138.6, 138.6, 138.2,
H), 4.14–4.08 (m, 2 H, H-5, H-5′), 3.79 (dd, 1 H, J6′a,6′b 10.7 138.0, 137.9 (7 × s, C-arom. quat.), 128.5–127.3 (35 × d, Ph),
Hz, J5′,6′a 2.7 Hz, 6′-Ha), 3.68 (dd, 1 H, J6′a,6′b 10.7 Hz, J5′,6′b 4.8 104.4 (C-2′), 86.5 (C-4), 83.5 (C-3′), 82.8 (C-2), 81.6 (C-3),
Hz, 6′-Hb), 3.68 (d, 1H, J1′a,1′b 10.7 Hz, 1′-Ha), 3.53 (d, 1 H, 81.4 (C-4′), 78.5 (C-5′), 75.4, 75.3, 73.3, 73.1, 72.5, 72.2 (6 ×
J1′a,1′b 10.7 Hz, 1′-Hb), 3.40 (dd, 1 H, J3,4 9 Hz, J4,5 3.3 Hz, 4-H), t, CH2Ph), 72.15 (C-1′), 71.8 (t, CH2Ph), 69.8 (C-6′), 68.7 (C-
3.36 (br d, 1 H, J 8.5 Hz, 2-H), 2.40 (dt, 1 H, J6a,6b 14.9 Hz, 5), 66.2 (C-1), 34.2 (C-6). MS (CI); m/z (%): 974.8 (100)
J1,6a = 5,6a 3.9 Hz, 6-Ha), 1.27 (m, 1 H, J6a,6b 14.9 Hz, 6-Hb). [MNH4+]. C61H64O10 (957.2): calcd C 76.55, H 6.74; found C
13C NMR (CDCl3): δ = 138.9, 138.8, 138.5, 138.0, 138.0, 76.48, H 6.76.
137.8, 137.8, (7 × s, C-arom. quat.), 128.2–127.3 (35 × d, Ph),
103.4 (C-2′), 82.7 (C-3′+ C-4), 81.5 (C-2+ C-4′), 79.1 (C-3),
The following side-products were also obtained:
78.6 (C-5′), 75.5, 73.1, 73.0, 73.0, 72.7, 72.2 (6 × t, CH2Ph),
71.8 (C-1′), 71.7 (t, CH2Ph), 69.6 (C-1), 69.5 (C-6′), 67.8 (C-
5), 32.1 (C-6′). MS (CI); m/z (%): 974.6 (100) [MNH4+].
C61H64O10 (957.2): calcd C 76.55, H 6.74; found C 76.45, H
6.92.
(20) (273 mg, 11%): as a colorless oil. [α]D22 +38 (c 0.8 in
CHCl3). 1H NMR (CDCl3): δ = 7.42–7.26 (m, 35 H, arom. H),
4.90–4.40 (m, 16 H, 7 × CH2Ph, 1-H, 5′-H), 4.24 (d, 1 H, J3′,4′
3.5 Hz, 3′-H), 3.95 (dd, 1 H, J4′,5′ 6.4 Hz, J3′,4′ 3.5 Hz, 4′-H),
3.75 (d, 1H, J1′a,1′b 10.3 Hz, 1′-Ha), 3.64 (d, 1 H, J1′a,1′b 10.3 Hz,
1′-Hb), 3.50–3.33 (m, 3 H, 6′-H, 5-H), 2.34 (m, 1 H, J6a,6b 13.8
1D-(1,2,4/3)-3,4-Di-O-benzyl-1,2,3,4,5-pentahydroxy-
cyclohexane (22) (158 mg, 17%), as a colorless oil. 1H NMR
(CDCl3): δ = 7.24–7.38 (m, 10H, Ph), 4.78, 4.89 (2 × d, 2H,
J 11.2, CH2Ph), 4.68 (s, 2H, CH2Ph), 4.14 (m, 1H, CHOH),
3.98 (m, 1H, CHOH), 3.87 (t, 1H, J3,4 = J2,3 8.6, 3-H), 3.5 (m, 2
H, CHOH and OH), 3.43 (dd, 1 H, J4,5 2.9, J3,4 8.6, 4-H), 3.23
(br s, 1 H, OH), 2.96 (br s, 1H, OH), 2.21 (dt, 1 H, J6a,6b 15.1,
6-Hb), 1.53 (dt, 1 H, J6a,6b 15.1 Hz, 6-Ha). MS (FAB); m/z (%):
367.3 (100) [MNa+].
1,2,4,6-Tetra-O-benzyl-2-isobutyl-2,5-anhydro-D-glucitol
Hz, 6-Ha), 1.41 (m, 1 H, 6-Hb). 13C NMR (CDCl3): δ= 140.8, (24) (376 mg, 15%), as a colorless oil. 1H NMR (CDCl3): δ =
138.7, 138.6, 138.1, 138.0, 137.9, 137.3, (7 × s, C-arom. 4.68, 4.65 (2 × d, 2H, J 11.5 Hz, CH2Ph), 4.64–4.58 (m, 6H, 3
quat.), 128.5–126.9 (35 × d, Ph), 108.4 (C-2′), 88.5 (C-3′), × CH2Ph), 4.18 (m, 1H, 2-H), 4.15 (dd, J2,3 5.6 Hz, J3,4 3.6 Hz,
83.3 (C-4′), 80.3 (C-5′), 73.5, 73.2, 72.8, 72.8, 72.1, 71.7 (6 × 3-H), 4.01 (d, 1H, J3,4 3.6 Hz, 4-H), 3.70 (dd, 1H, J1a,1b 10.35
t, CH2Ph), 69.7 (C-6′), 68.8 (C-1), 68.0 (C-1′), 67.7 (C-5), 65.1 Hz, J1b,2 5.15 Hz, 1a-H), 3.69 (d, 1H, J6a,6b 9.25 Hz, 6a-H), 3.64
(t, CH2Ph), 31.8 (C-6). MS (CI); m/z (%): 974.9 (45) [MNH4+], (d, 1H, J6a,6b 9.25 Hz, 6b-H), 3.63 (dd, 1H, J1a,1b 10.35 Hz, J1a,2
540.5 (80), 452.4 (100). C61H64O10 (957.2): calcd C 76.55, H 5.15 Hz, 1b-H), 1.9 (m, 1H, CH(CH3)2), 1.73 (d, 2H, J5.9 Hz,
6.74; found C 76.65, H 6.58.
CH2CH(CH3)2), 1.05 (d, 3H, J 6.6 Hz, CH3), 1.03 (d, 3H, J 6.6
(21) (31 mg, 1%), as a colorless oil. 1H NMR (CDCl3): δ = Hz, CH3) 13C NMR 138.56, 138.35, 138.33, 138.12, (4 × C-
7.39–7.26 (m, 35 H, arom. H), 5.04 (d, 1 H, J 11.2 Hz, CHPh), arom. quat.), 128.36, 128.31, 128.24, 128.145, 127.85,
4.93 (d, 1 H, J 10.9 Hz, CHPh), 4.86 (d, 1 H, J 12.1 Hz, 127.68, 127.65, 127.60, 127.58, 127.54, 127.49, 127.47,
CHPh), 4.75–4.42 (m, 13 H, 11 × CHPh, 1-H, 5′-H), 4.18 (d, 127.44, 127.275, (20 × d, Ph), 87.76 (C4), 85.89 (C5), 85.52
1 H, J3′,4′ 3.5 Hz, 3′-H), 4.15–4.09 (m, 1 H, 5-H), 4.03 (t, 1 H, (C2), 80.11 (C3), 73.29, 73.18, 72.26, 71.99 (4 × t, CH2Ph),
J2,3 = 3,4 9 Hz, 3-H), 3.97 (dd, 1 H, J4′,5′ 6.4 Hz, J3′,4′ 3.5 Hz, 4′-H), 71.21 (CH2OBn), 71.05 (CH2OBn), 42.10 (CH2CH(CH3)2),
3.75 (d, J1′a,1′b 10.3 Hz, 1′-Ha), 3.69 (d, J1′a,1′b 10.3 Hz, 1′-Hb), 24.60 (CH3), 24.30 (CH3), 23.78 (CH(CH3)2). MS (CI); m/z
3.44–3.41 (m, 3 H, 2-H, 6′-H), 3.34 (t, 1 H, J3,4 = 4,5 9 Hz, 4-H), (%): 598.6 [MNH4+].
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1,3,4,6-Tetra-O-benzyl-2,5-anhydro-D-glucitol (23)14 (28 (CDCl3): δ = 7.39–7.30 (m, 30 H, arom. H), 6.04 (ddt, 1 H, J
mg, 2%), as a colorless oil. Tetra-O-benzyl-2′-O-(4-O-allyl- 17.3 Hz, J 10.4 Hz, J 5.5 Hz, CH = CH2), 5.35 (ddt, 1 H, J 17.3
2,3-di-O-benzyl-6-deoxy-α-D-xylo-hex-5-enopyranosyl)-β-D- Hz, J 1.6 Hz, J 1.7 Hz, CH = CHH), 5.21 (ddt, 1 H, J 10.3 Hz,
fructofuranoside (3): Sodium hydride (0.9 g, 22.5 mmol, 60% J 1.7 Hz, J 1.0 Hz, CH = CHH), 4.87 (d, 1 H, J 10.7 Hz,
in mineral oil) was added to a stirred solution of 17 (4.4 g, 4.4 CHPh), 4.79 (d, 1 H, J 12.0 Hz, CHPh), 4.78 (d, 1 H, J 10.7
mmol) in anhydrous DMF (50 mL) containing allyl bromide Hz, CHPh), 4.70 (s, 2 H, CH2Ph), 4.67 (d, 1 H, J 11.6 Hz,
(0.8 mL, 8.9 mmol) at room temperature. After 18 h, TLC CHPh), 4.63 (br m, 1 H, 1-H), 4.57–4.50 (m, 4 H, 4 × CHPh),
(EtOAc/cyclohexane, 4:1) indicated no starting material (Rf 4.43 (d, 1 H, J3′,4′ 7.4 Hz, 3′-H), 4.39 (d, 1 H, J 12.0 Hz, CHPh),
0.3) and product (Rf 0.4), and the reaction mixture was cooled 4.31–4.18 (m, 4 H, OCH2CH, CHPh, 4′-H), 4.09–4.02 (m, 3
to 0 °C and methanol (15 mL) was carefully added dropwise. H, 3-H, 5-H, 5′-H), 3.74 (dd, 1 H, J6′a,6′b 10.8 Hz, J5′,6′a 2.7 Hz,
The solvent was removed in vacuo and the residue was parti- 6′-Ha), 3.63 (d, 1H, J1′a,1′b 10.7 Hz, 1′-Ha), 3.62 (dd, 1 H, J6′a,6′b
tioned between DCM (200 mL) and water (200 mL). The 10.8 Hz, J5′,6′b 3.5 Hz, 6′-Hb), 3.47 (d, 1 H, J1′a,1′b 10.7 Hz, 1′-
organic layer was washed with brine (100 mL), dried Hb), 3.32–3.28 (br m, 1 H, 2-H), 3.27 (dd, 1 H, J3,4 9.4 Hz, J4,5
(MgSO4), filtered, and the solvent was removed in vacuo. The 3.4 Hz, 4-H), 2.35 (dt, 1 H, J6a,6b 15.0 Hz, J1,6a = 5,6a 3.8 Hz, 6-
residue was purified by flash chromatography (EtOAc/cyclo- Ha), 1.26 (br d, 1 H, J 15.0 Hz, 6-Hb). 13C NMR (CDCl3): δ=
hexane, 1:7) to afford 3 (3.5 g, 88%), as a colorless oil. [α]D22 139.0, 138.6, 138.0, 138.0, 137.9, 137.9, (6 × s, C-arom.
+18 (c 1.0 in CHCl3). 1H NMR (CDCl3): δ = 7.39–7.27 (m, 30 quat.), 135.5 (CH = CH2), 128.3–127.4 (30 × d, Ph), 116.8 (CH
H, arom. H), 6.02 (ddt, 1 H, J 17.0 Hz, J 10.5 Hz, J 5.6 Hz, CH = CH2), 103.4 (C-2′), 82.8 (C-3′+ C-4), 81.6 (C-2), 81.5 (C-
= CH2), 5.79 (d, 1 H, J1,2 3.4 Hz, 1-H), 5.39 (ddt, 1 H, J 17.0 4′), 79.1 (C-3), 78.7 (C-5′), 75.6, 73.2, 73.1, 73.1, 72.8, 72.2 (6
Hz, J 1.7 Hz, J 1.5 Hz, CH = CHH), 5.26 (ddt, 1 H, J 10.5 Hz, × t, CH2Ph), 71.9 (C-1′), 71.3 (OCH2CH), 69.7 (C-1), 69.6 (C-
J 1.7 Hz, J 1.3 Hz, CH = CHH), 4.83 (s, 2 H, CH2Ph), 4.77 (br 6′), 68.0 (C-5), 32.1 (C-6′). MS (CI); m/z (%): 924.6 (95)
s, 1 H, 6-Ha), 4.74–4.56 (m, 10 H, 9 × CHPh, 6-Hb), 4.52 (m, [MNH4+], 540.3 (95), 402.2 (100). C57H62O10 (907.1): calcd C
1 H, 4′-H), 4.42 (d, 1 H, J 12.0 Hz, CHPh), 4.34-4.25 (m, 2 H, 75.47, H 6.89; found C 75.38, H 7.00. Further elution afforded
1
OCH2CH), 4.26–4.21 (m, 2 H, 3′-H, 5′-H), 3.94 (t, 1 H, J2,3 = 3,4 28 as a colorless oil. [α]D22 +46 (c 1.0 in CHCl3). H NMR
9.2 Hz, 3-H), 3.88–3.81 (m, 2 H, 4-H, 6′-Ha), 3.78 (d, 1 H, (CDCl3): δ = 7.39–7.29 (m, 30 H, arom. H), 6.00 (ddt, 1 H, J
J1′a,1′b 11.1 Hz, 1′-Ha), 3.75–3.72 (m, 1 H, 6′-Hb), 3.59 (d, 1 H, 17.1 Hz, J 10.5 Hz, J 5.8 Hz, CH = CH2), 5.34 (ddt, 1 H, J 17.1
J1′a,1′b 11.1 Hz, 1′-Hb), 3.57 (dd, 1 H, J2,3 9.2 Hz, J1,2 3.4 Hz, Hz, J 1.5 Hz, J 1.8 Hz, CH = CHH), 5.22 (ddt, 1 H, J 10.2 Hz,
2-H). 13C NMR (CDCl3): δ= 154.1 (C-5), 138.6, 138.4, 138.2, J 1.8 Hz, J 1.0 Hz, CH = CHH), 4.82–4.50 (m, 12 H, 11 ×
138.2, 138.2, 137.9 (6 × s, C-arom. quat.), 134.6 (CH = CH2), CHPh, 1-H), 4.48–4.44 (m, 1 H, OCHHCH), 4.46 (d, 1 H, J3′,4′
128.3–127.5 (30 × d, Ph), 117.1 (CH = CH2), 104.6 (C-2′), 7.3 Hz, 3′-H), 4.41 (d, 1 H, J 12.0 Hz, CHPh), 4.25 (dd, 1 H,
96.1 (C-6), 91.4 (C-1), 83.8 (C-4′), 82.5 (C-3′), 80.1 (C-3),
J4′,5′ 7.9 Hz, J3′,4′ 7.3 Hz, 4′-H), 4.26–4.19 (m, 1 H, OCHHCH),
79.8 (C-5′), 79.2 (C-2), 79.1 (C-4), 75.3, 73.3, 73.2, 73.0 (4 × t, 4.07 (ddd, 1 H, J4′,5′ 7.9 Hz, J5′,6′b 4.8 Hz, J5′,6′a 3.0 Hz, 5′-H),
CH2Ph), 73.0 (OCH2CH), 72.6, 72.5 (2 × t, CH2Ph), 71.8 (C- 4.00-3.93 (m, 1 H, 5-H), 3.84 (dd, 1 H, J2,3 9.7 Hz, J3,4 9.2 Hz,
6′), 70.5 (C-1′). MS (CI); m/z (%): 922.5 (100) [MNH4+]. 3-H), 3.76 (dd, 1 H, J6′a,6′b 10.6 Hz, J5′,6′a 3.0 Hz, 6′-Ha), 3.71-
C57H60O10 (905.1): calcd C 75.64, H 6.68; found C 75.68, H 3.62 (m, 3 H, 1′-H, 6′-Hb), 3.27 (dd, 1 H, J2,3 9.7 Hz, J1,2 3.2
6.68.
Hz, 2-H), 3.16 (t, 1 H, J3,4 = 4,5 9.2 Hz, 4-H), 2.49 (dt, 1 H, J6a,6b
13.5 Hz, J1,6a = 5,6a 4.5 Hz, 6-Ha), 2.10 (br d, 1 H, J 1.5 Hz OH),
1′,3′,4′,6′-Tetra-O-benzyl-2′-O-[1D-(1,2,4,5/3)-4-O-allyl- 1.20 (ddd, J6a,6b 13.5 Hz, J5,6b 11.8 Hz, J1,6b 1.9 Hz, 6-Hb). 13
C
2,3-di-O-benzyl-1,2,3,4,5-pentahydroxy-cyclohexyl]-β-D- NMR (CDCl3): δ= 138.8, 138.7, 138.6, 138.2, 138.0, 138.0 (6
fructofuranoside (27) and 1′,3′,4′,6′-Tetra-O-benzyl-2′-O- × s, C-arom. quat.), 135.5 (CH = CH2), 128.4–127.3 (30 × d,
[1D-(1,2,4/3,5)-4-O-allyl-2,3-di-O-benzyl-1,2,3,4,5- Ph), 116.8 (CH = CH2), 104.4 (C-2′), 86.2 (C-4), 83.5 (C-3′),
pentahydroxy-cyclohexyl]-β-D-fructofuranoside (28): TIBAL 82.7 (C-2), 81.5 (C-3), 81.4 (C-4′), 78.5 (C-5′), 75.4 (t,
(67.4 ml, 67.4 mmol, 1M in toluene) was added to a stirred CH2Ph), 74.1 (OCH2CH), 73.3, 73.2, 72.5, 72.2 (4 × t, CH2Ph),
solution of 3 (6.1 g, 6.7 mmol) in anhydrous toluene (6 mL) at 72.2 (C-1′), 71.8 (t, CH2Ph), 69.8 (C-6′), 68.7 (C-5), 66.2 (C-
room temperature under argon. After 4 h TLC (EtOAc/cyclo- 1), 34.1 (C-6′). MS (CI); m/z (%): 924.6 (100) [MNH4+].
hexane, 3:7) indicated no starting material (Rf 0.7) and two C57H62O10 (907.1): calcd C 75.47, H 6.89; found C 75.34, H
major products (Rf 0.4 and 0.3) as part of a complex mixture. 6.92.
The mixture was cooled to 0 °C and icewater (250 mL) was
added. The mixture was filtered (Celite) into a separatory
1′,3′,4′,6′-Tetra-O-benzyl-2′-O-[1D-(1,2,4/3)-4-O-αllyl-
funnel, washing with EtOAc (250 mL), and the aqueous layer 2,3-di-O-benzyl-1,2,3,4-tetrahydroxy-cyclohex-5-onyl]-β-D-
was extracted with EtOAc (3 × 250 mL). Combined organic fructofuranoside (31): Acetic anhydride (27.1 mL, 0.3 mol)
extracts were dried (MgSO4), filtered, and the solvent was was added to a stirred solution of 27/28 (2.7 g, 3.0 mmol as a
removed in vacuo. The residue was purified by flash chroma- 1:1 mixture) in anhydrous DMSO (135 mL) at room tempera-
tography (eluent gradient, 9–30% EtOAc in cyclohexane) to ture under argon. The reaction mixture was stirred for 16 h.
afford 27/28 (1.7 g, 28% as a 1:1 mixture). Further flash TLC (EtOAc/cyclohexane, 3:7) indicated no starting material
chromatography (eluent gradient, 20–30% EtOAc in cyclo- (Rf 0.4) and formation of product (Rf 0.5). The reaction mix-
hexane) of a small quantity of the mixture afforded first pure ture was diluted with EtOAc (1.5 L) and then washed with
1
27 as a colorless oil. [α]D22 +15 (c 1.0 in CHCl3). H NMR water (400 mL), brine (400 mL), dried (MgSO4), filtered, and
du Roizel et al. / TIBAL-Promoted Rearrangement of Sucrose-5-enes

324
the solvent was removed in vacuo. The residue was purified by
flash chromatography (20% EtOAc in cyclohexane) to afford
31 (2.0 g, 57%), as a colorless oil. [α]D22 +24 (c 1.0 in CHCl3).
1H NMR (CDCl3): δ = 7.38–7.29 (m, 30 H, arom. H), 6.01
(ddt, 1 H, J 17.3 Hz, J 10.5 Hz, J 5.7 Hz, CH = CH2), 5.36 (ddt,
1 H, J 17.3 Hz, J 1.5 Hz, J 1.6 Hz, CH = CHH), 5.24 (ddt, 1 H,
J 9.3 Hz, J 1.5 Hz, J 1.1 Hz, CH = CHH), 4.81–4.56 (m, 10 H,
9 × CHPh, 1-H), 4.54 (s, 2 H, CH2Ph), 4.44 (d, 1 H, J 11.9 Hz,
CHPh), 4.43 (d, 1 H, J3′,4′ 7.1 Hz, 3′-H), 4.42-4.38 (m, 1 H,
OCHHCH), 4.18–4.05 (m, 3 H, 4′-H, 5′-H, OCHHCH), 4.00
(t, 1 H, J2,3 = 3,4 8 Hz, 3-H), 3.95 (d, 1 H, J3,4 8 Hz, 4-H), 3.73–
3.68 (m, 3 H, 2-H, 6′-H), 3.67 (d, 1H, J1′a,1′b 10.7 Hz, 1′-Ha),
3.63 (d, 1 H, J1′a,1′b 10.7 Hz, 1′-Hb), 2.97 (dd, 1 H, J6a,6b 15.0
Hz, J5,6a 5.2 Hz, 6-Ha), 2.30 (dd, J6a,6b 15.0 Hz, J5,6b 3.4 Hz, 6-
Hb). 13C NMR (CDCl3): δ = 204.3 (C-5), 138.5, 138.4, 138.4,
138.1, 138.0, 137.9 (6 × s, C-arom. quat.), 134.5 (CH = CH2),
128.3–127.4 (30 × d, Ph), 117.5 (CH = CH2), 104.8 (C-2′),
85.4 (C-4), 83.5 (C-3′), 81.9 (C-4′), 81.6 (C-3), 81.0 (C-2),
78.5 (C-5′), 75.1, 73.4, 73.0 (3 × t, CH2Ph), 72.6 (OCH2CH),
72.5, 72.5 (2 × t, CH2Ph), 72.3 (C-1′), 71.9 (t, CH2Ph), 70.1 (C-
6′), 66.9 (C-1), 42.6 (C-6). MS (CI); m/z (%): 922.7 (30)
[MNH4+], 326.2 (100). C57H60O10 (905.1): calcd C 75.64, H
6.68; found C 75.65, H 6.78.
(3) Sollogoub, M.; Mallet, J.-M.; Sinaÿ, P. Angew. Chem.,
Int. Ed. Engl. 2000, 39, 362–364.
(4) Pearce, A.J.; Sollogoub, M.; Mallet, J.-M.; Sinaÿ, P.
Eur. J. Org. Chem. 1999, 2103–2117.
(5) Sollogoub, M.; Pearce, A.J.; Hérault, A.; Sinaÿ, P. Tet-
rahedron: Asymmetry 2000, 11, 283–294.
(6) Pearce, A.J.; Mallet, J.-M.; Sinaÿ, P. Heterocycles
2000, 52, 819–826.
(7) Pearce, A.J.; Chevalier, R.; Mallet, J.-M.; Sinaÿ, P. Eur.
J. Org. Chem. 2000, 2203–2206.
(8) We have recently demonstrated that acyclic non-carbo-
hydrate-based substituted vinyl ethers also undergo
TIBAL-promoted reductive rearrangement; see du
Roizel, B.; Sollogoub, M.; Pearce, A.J.; Sinaÿ, P.
Chem. Commun. 2000, 1507–1508.
(9) Fanton, E.; Gelas, J.; Horton, D.; Karl, H.; Khan, R.;
Lee, C.-K.; Patel, G. J. Org. Chem. 1981, 46, 4057–
4060.
(10) (a) Hough, L.; Kabir, A.K.M.S.; Richardson, A.C.
Carbohydr. Res. 1984, 125, 247–252. (b) Chiu, A.K.B.;
Hough, L.; Richardson, A.C.; Toufeili, I.A.; Dziedzic,
S.Z., Carbohydr. Res. 1987, 162, 316–322.
(11) Garegg, P.; Samuelsson, B. J. Chem. Soc., Perkin
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Acknowledgment. We thank the European Community for a
TMR Marie Curie Research Training Grant (#ERBFMBICT-
983225) to A.J.P.
(12) (a) Krog-Jensen, C.; Oscarson, S. J. Org. Chem. 1996,
61, 1234–1238. (b) Angyal, S.J.; Bethell, G.S. Aust. J.
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(13) Kaesbeck, L.; Kessler, H. Liebigs Ann. Org. Bioorg.
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