Stereocontrolled oxycarbonylation of 4-benzyloxyhepta-1,6-diene-3,5-diols promoted by chiral palladium(II) complexes

Article abstract of DOI:10.1016/j.tetasy.2007.12.003

The synthesis of all diastereomers of 4-benzyloxyhepta-1,6-diene-3,5-diols 8-10 is described. The diastereo- and enantioselectivity of palladium(II)-catalysed oxycarbonylation of the symmetric compounds 8-10 were studied. The substrates 8-10 underwent Pd(II)-initiated oxycarbonylative bicyclisation to afford bicyclic lactones 11-14 in good yields and with excellent threo-diastereoselectivity. Additionally, the synthesis of enantiomerically pure lactone d-gluco-12, precursor for syntheses of goniofufurone and 7-epi-goniofufurone, was developed.

Full text of DOI:10.1016/j.tetasy.2007.12.003

Available online at www.sciencedirect.com
Tetrahedron: Asymmetry 19 (2008) 38–44
Stereocontrolled oxycarbonylation of 4-benzyloxyhepta-1,6-diene-
3,5-diols promoted by chiral palladium(II) complexes
*
´
Peter Kapitan and Tibor Gracza
Department of Organic Chemistry, Institute of Organic Chemistry, Catalysis and Petrochemistry, Slovak University of Technology,
Radlinske´ho 9, SK-812 37 Bratislava, Slovakia
Received 2 October 2007; accepted 16 December 2007
Abstract—The synthesis of all diastereomers of 4-benzyloxyhepta-1,6-diene-3,5-diols 8–10 is described. The diastereo- and enantioselec-
tivity of palladium(II)-catalysed oxycarbonylation of the symmetric compounds 8–10 were studied. The substrates 8–10 underwent
Pd(II)-initiated oxycarbonylative bicyclisation to afford bicyclic lactones 11–14 in good yields and with excellent threo-diastereoselectivity.
Additionally, the synthesis of enantiomerically pure lactone D-gluco-12, precursor for syntheses of goniofufurone and 7-epi-gonio-
fufurone, was developed.
Ó 2007 Elsevier Ltd. All rights reserved.
OH
1. Introduction
O
O
Pd(II)/CO
R
R
Palladium(II)-catalysed reactions are fundamentally
important in organic transformations due to the versatility,
selectivity and overall synthetic usefulness of palladium.1
Amongst the most interesting and synthetically useful reac-
tions using palladium as a catalyst are cyclisations of unsat-
urated alcohols, amines and other suitable substrates
accompanied by the insertion of carbon monoxide.2 Pd-
catalysed carbonylation is a very attractive method due
to the effective one-carbon homologation it accomplishes.
These reactions provide a simple and straightforward
access to esters or amides. Intramolecular versions of these
processes have proven particularly useful for construction
of a range of oxygen and nitrogen-containing hetero-
cycles.3 Early examples of this domino reaction include
Pd(II)-promoted cyclisation—intramolecular oxycarbon-
ylations were described for 1,4- and 1,3-alkenediols,
providing preferably cis-fused bicyclic lactones having
tetrahydropyran4 and/or tetrahydrofuran5 structural
motifs, respectively (Scheme 1).
X
XH
X = O, NP
R = OH, protected OH (OP), H, R
Scheme 1. Intramolecular Pd(II)-catalysed oxy-/amidocarbonylation of
unsaturated polyols and/or aminopolyols.
erythroskyrine,6g kumausyne,6h Hagen’s gland lactones,6i
and/or plakortones6j–l (Fig. 1).
The Pd(II)-induced intramolecular attack of heteroatom
nucleophiles on alkenes with subsequent carbonylation
leads to r-acylpalladium intermediates, which in turn can
react further to carboxylic acid derivatives. This chemistry
enables highly efficient domino transformations, which are
of outstanding value for the synthesis of complex hetero-
cyclic molecules. While in many cases the chemo- and regio-
selectivities of such reactions can be efficiently controlled
by the proper choice of substrates and reaction conditions,
the control of absolute configuration in the case of chiro-
genic reactions still remains a challenge for research and
development. Recently, we have communicated the first
asymmetric intramolecular oxycarbonylation of an unsatu-
rated diol, catalysed by chiral palladium(II) complexes.7
The kinetic resolution of racemic pent-4-ene-1,3-diol ( )-
1 in the presence of Pd(OAc)2-{(R,S)-indabox}, p-benzo-
Such transformation of enantiomerically pure substrates
has found numerous applications in the total syntheses of
natural compounds frenolicine,6a,b kalafungin,6b gon-
iofufurone,6c,d 7-epi-goniofufurone,6c,d goniothalesdiol,6e,f
*
Corresponding author. Tel.: +421 2 593 25160; fax: +421 2 529 68560;
e-mail: tibor.gracza@stuba.sk
quinone in acetic acid under a carbon monoxide
0957-4166/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetasy.2007.12.003

P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
39
HO
HO
HO
Ph
OH
O
O
O
O
HO
HO
CO2Me
O
O
O
Ph
Ph
(+)-7-epi-goniofufurone
(+)-goniofufurone
(+)-goniothalesdiol
OH
O
O
HO
O
HO
O
N
O
O
Ph
(+)-altholactone
O
(+)-erythroskyrine
Figure 1.
atmosphere afforded enantiomerically enriched (1R,5R)-
2,6-dioxabicyclo[3.3.0]octan-3-one (R,R-2) in 29% yield
and 62% ee (Scheme 2).
known routes to the protected 1,2:4,5-dianhydropentitols
5–7 (Scheme 4). These key intermediates have previously
been used in the preparation of pentitol derivatives from
divinyl methanol;8 for the synthesis of 1-deoxy-4-thio-L-
ribose;9 in the preparation of a C2-symmetric HIV protease
inhibitor;10 in the synthesis of immunosuppressive agent
FK-506;11 in the preparation of polysubstituted piperi-
dines;12 and in the synthesis of caribenolide I.13 The overall
strategy for our synthesis is shown in Scheme 3.
CO (balloon)
Pd(OAc)2 (0.025 equiv.)
(R,S)-indabox (0.075 equiv.)
O
O
OH OH
(S)-1
+
p-benzoquinone (0.5 equiv.)
O
AcOH
( )-1
(R,R)-2
(29%, 62% ee)
This route comprises the formation of 1,2:4,5-dianhydro-
pentitols from the corresponding pentitols followed by
introduction of both terminal C@C double bonds by treat-
ment with an excess of dimethylsulfonium methylide. The
required 1,2:4,5-dianhydropentitols were prepared from
pentitols, as reported,12,14 by a slightly modified procedure
in one pot. Indeed, xylitol and D-arabitol were made to
react with p-toluenesulfonyl chloride in pyridine, respec-
tively, to give crude ditosylates, which were directly con-
verted to the bis-epoxide benzyl ethers 5 and 6 in 25%
and 26% overall yield, respectively, by treatment with
sodium hydride and alkylation with benzyl bromide
(Scheme 4).
Scheme 2. Kinetic resolution of ( )-1 in an asymmetric Pd(II)-catalysed
oxycarbonylation.
In this paper, we report our studies on the enantio- and
diastereoselectivity of oxycarbonylative bicyclisation of 4-
benzyloxyhepta-1,6-diene-3,5-diols promoted by chiral
Pd(II) complexes.
2. Results and discussion
Having obtained preliminary success with the use of chiral
Pd(II)-complexes in oxycarbonylative kinetic resolution of
pent-4-ene-1,3-diol (Scheme 1), we now focused on the
asymmetric Pd(II)-catalysed alkoxycarbonylation of sym-
metric substrates with full conversion. The hepta-1,6-
diene-3,4,5-triols were chosen as suitable substrates for
the exploration of this transformation. Moreover, meso-
diols 8 and 10 with xylo and ribo relative configuration,
respectively, serve as precursors for the syntheses of althol-
actone and goniothalesdiol. The pseudo-C2-symmetric D-
arabino-derivative 9 is an intermediate for the preparation
of goniolactones and erythroskyrine (Fig. 1).
The 3-benzyl-1,2:4,5-dianhydroribitol 7 was prepared from
ribitol in 29% yield over 4 steps following Thomas’s12
synthetic sequence. Initially, protection of the terminal
hydroxyl groups of ribitol as their acetonides using di-
methoxypropane in acetone and a catalytic amount of p-
toluenesulfonic acid in anhydrous DMF, followed by
benzylation of the free hydroxy group at C3 with benzyl
bromide furnished a fully protected ribitol. The epoxides
were generated via Mitsunobu reaction on the two terminal
hydroxyl groups after acidic removal of the isopropylidene
protecting groups to give 7. Finally, the carbon chain of the
dianhydropentitols 5–7 was elongated by the reaction with
dimethylsulfonium methylide to give the hepta-1,6-diene-
diols 8–10. Adopting the protocol for the transformation
of epoxides to allylic alcohols,15,16 diepoxides 5–7 were
2.1. Synthesis of substrates
The hepta-1,6-diene-3,4,5-triols 8–10 were prepared from
ribitol, xylitol and D-arabitol, respectively, adopting
O
O
OH OH
OBn
S
OH OH
HO
OH
OBn
OH
Scheme 3. General strategy for synthesis of 4-benzyloxyhepta-1,6-diene-3,5-diols.

40
P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
temperature. This system, used in various Pd(II)-catalysed
OH OH
O
O
O
O
reactions previously,2,3 had been shown to be advanta-
geous for intramolecular carbonylation.3c,d,4,5 The enitols
8–10 (entries 1–3) on such treatment all underwent slow
conversion, which could be monitored by a colour change
of the reaction suspension from green to ochre. In all cases,
the corresponding cis-fused bicyclic lactones 11–14 were
obtained in good yields and with high threo-selectivity with
respect to the newly formed stereogenic centre at C5, as
expected. In the reaction of the pseudo-C2-symmetric enitol
9, the diastereomer D-gluco-12 was isolated as the major
product (65% yield, resulting from intramolecular Si-attack
of the nucleophilic hydroxyl group to the Pd(II)-activated
double bond) along with its minor diastereomer D-galacto-
13 (9%) (entry 2). Such a product distribution is most
probably due to the endo-positions of two attached substit-
uents on fused rings of the lactone D-galacto-13, an
arrangement that in consequence increased the steric hin-
drance, and therefore the formation of 13 was slowed
down. In fact, simply raising the temperature to 60 °C led
to the complete consumption of enitol 9 in only 30 min
to form energetically favourable diastereomer D-gluco-12
as the sole product in 78% yield (entry 4).
a
c
xylitol
D-arabitol
ribitol
25%
60%
OBn
8 (xylo)
OBn
5
OH OH
*
O
a
c
*
26%
60%
OBn
9 (D-arabino)
OBn
6
OH OH
O
b
c
29%
66%
OBn
10 (ribo)
OBn
7
Scheme 4. Synthesis of 4-benzyloxyhept-1,6-diene-3,5-diols 8–10.
Reagents and conditions: (a) (i) TsCl (2 equiv), pyridine, ꢀ10 °C; (ii)
NaH (3.3 equiv), THF, 0 °C; BnBr (1.1 equiv), 0 °C to rt, 20 h; (b) (i)
dimethoxypropane, acetone, TsOH, DMF, 20 °C, 12 h (69%); (ii) NaH
(1.1 equiv), BnBr (1.2 equiv), THF, ꢀ10 °C (78%); (iii) PPh3 (2.3 equiv),
DEAD (2.3 equiv), toluene, 110 °C, 12 h (53%); (c) Me3SI (6.6 equiv), n-
BuLi (6.0 equiv), THF, 0–25 °C.
treated with an excess of dimethylsulfonium methylide pro-
viding the corresponding key substrates 8–10.
Next, the asymmetric oxycarbonylations of meso-sub-
strates 8 and 10 were examined. Based on the observed
enantioselectivity (62% ee7) in the kinetic resolution of
racemic pent-4-ene-1,3-diol ( )-1, the higher stereodifferen-
tiation of the double bond in hepta-1,6-diene-diols 8 and
10 in the asymmetric alkoxycarbonylation was expected
due to the bulky benzyloxy and vinyl groups of sub-
strates. The first trial was effected with 8 in the presence
of Pd(OAc)2 (0.1 equiv), {(3aR,8aS)-(8,8a)-dihydro-
3aH-indeno[1,2-d]oxazol-2-yl}methane A, [(R,S)-indabox]
(0.12 equiv) and p-benzoquinone (1.1 equiv) in acetic acid
under carbon monoxide at 25 °C (entry 5). Surprisingly,
the required lactone D-ido-11 was obtained in 63% yield,
albeit with only poor enantiomeric purity (11% ee). Simi-
larly, the use of ligand with opposite asymmetric induction7
B [(S,S)-bis(4-isopropyloxazol-2-yl)methane] under the
same reaction conditions furnished only racemic product
ido-11 (entry 6).
The hepta-1,6-diene-3,4,5-triols 8–10, respectively, to the
best of our knowledge have not yet been reported in the lit-
erature; we expect them to be highly interesting, versatile
building blocks in other areas.
2.2. Palladium(II)-catalysed oxycarbonylations
With all substrates 8–10 in our hands, we subjected them to
Pd(II)-catalysed oxycarbonylation under various reaction
conditions (Scheme 5, Table 1).
Firstly, the reaction was carried out with palladium(II)
chloride (catalyst, 0.1 equiv), copper(II) chloride (oxidant,
3 equiv), and sodium acetate (buffer, 3 equiv) in acetic acid
under carbon monoxide at normal pressure and at room
OBn
BnO
OH
OH
O
O
O
O
O
O
a
a
a
+
O
O
OBn
8 (xylo)
L-ido-11
D-ido-11
OBn
BnO
OH
OH
O
O
O
+
O
O
D-galacto-13
OBn
9 (D-arabino)
D-gluco-12
BnO
OH
OBn
OH
O
O
O
+
O
O
OBn
10 (ribo)
L-altro-14
D-altro-14
Scheme 5. Pd(II)-Catalysed oxycarbonylation of 4-benzyloxyhepta-1,6-diene-3,5-diols 8–10. Reagents and conditions: (a) see Table 1.

P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
Table 1. Pd(II)-catalysed oxycarbonylation of 4-benzyloxyhepta-1,6-diene-3,5-diols 8–10
41
Entry
1
Substrate
Solvent
AcOH
Catalyst and additive(s)
Conditionsa
Product(s), yieldb
eec (%)
—
8
0.1 equiv PdCl2, 3 equiv
CuCl2, 3 equiv AcONa
0.1 equiv PdCl2, 3 equiv
CuCl2, 3 equiv AcONa
0.1 equiv PdCl2, 3 equiv
CuCl2, 3 equiv AcONa
0.1 equiv PdCl2, 3 equiv
CuCl2, 3 equiv AcONa
0.1 equiv Pd(OAc)2, 0.12 equiv
A,e 1.1 equiv BQ
25 °C, 12 h
ido-11 (72%)
2
3
9
10
9
AcOH
25 °C, 20 h
25 °C, 12 h
65 °C, 30 min
20 °C, 24 h
20 °C, 24 h
40 °C, 24 h
20 °C, 4 d
20 °C, 4 d
20 °C, 5 d
20 °C, 4 d
D-gluco-12 (65%) D-galacto-13 (9%)
altro-14 (66%)
—
—
—
11
—
13
11
7
AcOH
4
AcOH
D-gluco-12 (78%)
D-ido-11d (63%)
5
8
AcOH
6
8
AcOH
0.1 equiv Pd(OAc)2, 0.12 equiv
B,e 1.1 equiv BQ
ido-11 (67%)
7
8
CH2Cl2
0.1 equiv Pd(TFA)2,
D-ido-11d (15%)
0.12 equiv A,e 1.1 equiv BQ
0.05 equiv Pd(TFA)2,
8
8
AcOH/CH2Cl2 (1:8)
AcOH/CH2Cl2 (1:8)
AcOH/CH2Cl2 (1:8)
AcOH/CH2Cl2 (1:8)
D-ido-11d (63%)
0.15 equiv A,e 4 equiv BQ
0.05 equiv Pd(TFA)2,
9
8
L-ido-11d (79%)
0.15 equiv B,e 4 equiv BQ
0.05 equiv Pd(TFA)2,
10
11
10
10
D-altro-14d (61%)
L-altro-14d (77%)
12
7
0.15 equiv A,e 4 equiv BQ
0.05 equiv Pd(TFA)2,
0.15 equiv B,e 4 equiv BQ
a All runs were carried out under carbon monoxide at normal pressure (balloon).
b Isolated yields after flash column chromatography.
c Enantiomeric excesses were determined using gas chromatography with chiral stationary phase.
d Tentative absolute configuration based on previous results7 with these catalysts in the oxycarbonylative kinetic resolution of pent-4-ene-1,3 diol.
e Chiral ligands.
O
O
O
O
N
N
N
N
A
B
We then turned our attention to a closer examination of
the reaction conditions. Initially, different Pd(II)-salts and
solvents were checked. Simply changing from Pd(OAc)2
in AcOH to Pd(TFA)2 in dichloromethane resulted in de-
crease of the yield of D-ido-11 from 63% (entry 5) to 15%
(entry 7). A significant counterion and solvent dependence
was also observed in our work on the oxycarbonylative
kinetic resolution of pentene–diol7 and points to an exceed-
ingly subtle reason for the general reactivity of interme-
diates in this catalytic reaction. Then we decided to
investigate the relative stoichiometry of reagents used in
the reaction and found that in the presence of Pd(TFA)2
(0.05 equiv), chiral ligand (0.15 equiv) and p-benzoquinone
(4 equiv) in the mixture of CH2Cl2–AcOH (8:1) the reac-
tion was improved to give the corresponding products in
good yields, however, with the same low enantioselectivity
(entries 8–11). Interestingly, the presence of AcOH seems
to be important for accomplishment of asymmetric oxy-
carbonylation. Unfortunately, not even the increased ratio
of catalyst/ligand (1:3) effected the desired enantio differen-
tiation of alkenes 8 and 10.
9 represents a useful C7-chain building block. The meso-
enitols 8 and 10 serve excellent substrates for asymmetric
transformations.
The diastereo- and enantioselectivity of palladium(II)-catal-
ysed oxycarbonylation of dienols 8–10 were studied. The
4-benzyloxyhepta-1,6-diene-3,5-diols undergo Pd(II)-initi-
ated oxycarbonylative bicyclisation to afford bicyclic
lactones in good yields and with excellent threo-diastereo-
selectivity. In addition, we have demonstrated the value
of this method in the synthesis of enantiomerically pure
lactone D-gluco-12, precursor for syntheses of goniofufu-
rone and 7-epi-goniofufurone (Fig. 1).
Although the level of asymmetric induction achieved so far
is rather poor, this is the first report on the asymmetric ver-
sion of this transformation in the desymmetrisation of
meso-substrates. Further studies to improve the perfor-
mance of the asymmetric catalysts for this transformation
are ongoing.
4. Experimental
4.1. General
3. Conclusion
In conclusion, we have developed the synthesis of all dia-
stereomers of 4-benzyloxyhepta-1,6-diene-3,5-diols 8–10,
respectively. The pseudo-C2-symmetric D-arabino-alkenitol
Commercial reagents were used without further purifica-
tion. All solvents were distilled before use. Hexanes refer

42
P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
to the fraction boiling at 60–65 °C. Flash column liquid
chromatography (FLC) was performed on Silica Gel Kie-
selgel 60 (40–63 lm, 230–400 mesh) and analytical thin-
layer chromatography (TLC) was performed on aluminium
plates pre-coated with either 0.2 mm (DC-Alufolien,
Merck) or 0.25 mm Silica Gel 60 F254 (ALUGRAMÒ
SIL G/UV254, Macherey-Nagel). The compounds were vis-
ualised by UV fluorescence and by dipping the plates in an
aqueous H2SO4 solution of cerium sulfate/ammonium
molybdate followed by charring with a heat gun. General
conversion control and analyses of purified products were
performed on a GC Top 8000/MS Voyager (quadropol,
EI+) using a standard capillary column BGB5 (30 mP
0.32 mm ID). Enantiomeric excesses were determined by
chiral-phase GC using a BGB 175 column (30 mP
0.25 mm ID, 0.25 mm film) and a BGB 173 column
(30 mP 0.25 mm ID, 0.25 mm film) on a ThermoQuest
Trace GC 2000 and a Thermo Focus GC. Melting points
were obtained using a Kofler hot plate and are uncorrected.
Optical rotations were measured with a POLAR L-lP
polarimeter (IBZ Messtechnik) with a water-jacketed
10.000 cm cell at the wavelength of sodium D line
(k = 589 nm). Specific rotations are given in units of
10ꢀ1 deg cm2 gꢀ1 and concentrations are given in g/
100 mL. Elemental analyses were run on FISONS
EA1108 instrument. Infrared spectra were recorded either
on a Philips Analytical PU9800 FTIR spectrometer or a
Perkin–Elmer 1750 FTIR spectrophotometer as KBr discs
(KBr) or as thin films on KBr plates (film). NMR spectra
were recorded on a Varian VXR-300 spectrometer. Chem-
ical shifts (d) are quoted in ppm and are referenced to the
tetramethylsilane (TMS) as internal standard. The multi-
plicities of carbons were assigned from a broadband decou-
pled analysis used in conjunction with either APT or DEPT
programs.
2H, 1-HB, 5-HB); 3.10–3.16 (m, 3H, 2-H, 3-H, 4-H); 4.76
(s, 2H, CH2Ph); 7.28–7.40 (m, 5H, Ph); 13C NMR
(75 MHz, CDCl3): d 43.2 (t, C-1, C-5), 52.0 (d, C-2, C-4),
71.9 (t, CH2Ph), 79.4 (d, C-3), 127.7, 127.9, 128.4 (all d,
Ph), 137.8 (s, Ph). HRMS for C12H14O3 (M+): calcd,
206.0943; found, 206.0947.
4.2.2. 3-O-Benzyl-1,2:4,5-dianhydro-D-arabitol 6. Pre-
pared as described for 5 from D-arabitol (5.0 g, 33 mmol).
The crude product was purified by flash column chromato-
graphy (50 g of silica gel, Et2O–hexanes; 1:4); yield 1.73 g
(26%), as a colourless oil, Rf 0.30 (Et2O–hexanes, 1:1);
25
22
½aꢂD ¼ þ31 (c 0.65, CHCl3); {lit.14: ½aꢂD ¼ þ29:8 (c
1.0, CHCl3)}; HRMS for C12H14O3 (M+): calcd
206.0943, found 206.0940. The spectral data are in good
agreement with those reported in the lit.14
4.2.3. 3-O-Benzyl-1,2:4,5-dianhydroribitol 7. Prepared
from 3-O-benzyl-ribitol,17 modifying the procedures of
Thomas.12 To a suspension of 3-O-benzyl-ribitol (1.0 g,
4.1 mmol) and PPh3 (2.79 g, 2.6 equiv) in anhydrous tolu-
ene at rt was added DEAD (1.7 mL, 2.6 equiv) dropwise
and stirring was continued at rt for 30 min. The yellow
solution was then heated at 110 °C for 12 h. The solvent
was removed in vacuo, Et2O (100 mL) was added and pre-
cipitated triphenylphosphine oxide was filtered off and
washed with Et2O (2 ꢁ 20 mL). After drying over MgSO4
and evaporation a yellow oil was obtained, which was puri-
fied by flash chromatography (40 g silica gel, AcOEt–hex-
anes, 1:6). Yield 450 mg (53%), as a colourless oil, Rf
0.67 (AcOEt–hexanes, 1:2); IR (film, cmꢀ1): m 3065, 3031,
2994, 2930, 1493, 1454; 1H NMR (300 MHz, CDCl3):
d 2.75–2.81 (m, 4H, 1-H, 5-H); 3.09–3.13 (m, 2H, 2-H, 4-
H); 3.36 (t, 1H, J = 5 Hz, 3-H); 4.64 (s, 2H, CH2Ph);
7.31–7.36 (m, 5H, Ph); 13C NMR (75 MHz, CDCl3):
d 44.6 (t, C-1, C-5), 51.1 (d, C-2, C-4), 72.7 (t, CH2Ph),
76.8 (d, C-3), 127.7, 127.9, 128.4 (all d, Ph), 137.9 (s, Ph).
HRMS for C12H14O3 (M+): calcd, 206.0943; found,
206.0940.
4.2. Synthesis of dianhydroalditols 5–7
4.2.1. 3-O-Benzyl-1,2:4,5-dianhydroxylitol 5. Toluenesul-
fonyl chloride (6.3 g, 33 mmol, 2 equiv) in pyridine
(12 mL) was added to a solution of xylitol (2.5 g, 16 mmol)
in pyridine (10 mL) at ꢀ10 °C over 45 min. The reaction
mixture was stirred at ꢀ10 °C for further 15 min and then
poured onto ice (250 g). HCl (2 M, 75 mL) was then added.
The aqueous layer was extracted with CH2Cl2
(3 ꢁ 100 mL), dried over Na2SO4 and concentrated. The
residue (6.2 g, 83%) was used in the next reaction without
any purification. To solution of the crude ditosylate
(6.2 g) in anhydrous THF (200 mL), NaH (1.72 g, 60% in
paraffin, 45 mmol, 3.3 equiv) was added at 0 °C and the
mixture was stirred at 0 °C for 30 min and subsequently
BnBr (1.7 mL, 15 mmol) was added. The reaction mixture
was stirred overnight at room temperature, quenched with
water (50 mL), and extracted with CH2Cl2 (3 ꢁ 40 mL).
The organic layers were combined, dried over Na2SO4
and concentrated in vacuo. The pure 3-O-benzyl-1,2:4,5-
dianhydroxylitol 5 was obtained by flash column chroma-
tography (50 g of silica gel, Et2O–hexanes, 1:5); yield
860 mg (25%), as a colourless oil, Rf 0.29 (Et2O–hexanes,
1:1); IR (film, cmꢀ1): m 3063, 3031, 2992, 2921, 2862,
1492, 1454, 1085; 1H NMR (300 MHz, CDCl3): d 2.67
(dd, 2H, J = 2 Hz, J = 5 Hz, 1-HA, 5-HA); 2.79–2.82 (m,
4.3. Synthesis of the symmetric dienes 8–10
4.3.1. (xylo)-4-Benzyloxyhepta-1,6-diene-3,5-diol 8. Accord-
ing to the literature,16 to a stirred mixture of trimethylsulfo-
nium iodide (9.83 g, 48 mmol, 6.6 equiv) in anhydrous THF
(100 mL) was added butyllithium (20 mL, 2.0 M in hexane,
6 equiv) at ꢀ 10 °C. The resulting mixture was stirred at
ꢀ10 °C for 30 min and a solution of diepoxide 5 (1.5 g,
7.3 mmol) in dry THF (50 mL) was added. The reaction mix-
ture was stirred at room temperature for 2 h, hydrolysed
with water (60 mL), extracted with CH2Cl2 (3 ꢁ 30 mL),
dried over MgSO4 and concentrated. The crude product
was purified by Kugelrohr distillation under reduced pres-
sure (175 °C/0.02 Torr) to yield compound 8 (1.06 g, 60%
yield), as a colourless oil, Rf 0.24 (AcOEt–hexanes, 1:2); IR
(film, cmꢀ1): m 3399, 3082, 3024, 2921, 1725, 1454; 1H
NMR (300 MHz, CDCl3): d 2.38 (br s, 2H, OH); 3.38
(t, 1H, J3,4 = J4,5 = 5 Hz, 4-H); 4.29–4.32 (m, 2H, 3-H, 5-
H); 4.69 (s, 2H, CH2Ph); 5.25 (ddd, 2H, J1A,2 = 10 Hz,
J1A,1B = J1A,3 = 1 Hz, 1-HA, 7-HA); 5.41 (ddd, 2H,
J1B,2 = 17 Hz, J1A,1B = J1B,3 = 1 Hz, 1-HB, 7-HB); 5.89–
6.00 (m, 2H, 2-H, 6-H); 7.29–7.36 (m, 5H, Ph); 13C NMR

P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
43
(75 MHz, CDCl3): d 72.7 (d, C-3, C-5), 75.5 (t, CH2Ph), 84.3
(d, C-4), 116.9 (t, C-1, C-7), 128.1, 128.2, 128.6 (all d, Ph),
137.5 (s, Ph), 137.7 (d, C-2, C-6). Anal. Calcd for
C14H18O3 (234.3): C 71.77; H 7.74. Found: C 71.37; H 7.80.
(film, cmꢀ1): m 3032, 2934, 1789, 1062; 1H NMR
(300 MHz, CDCl3): 2.69 (dd, of ABX, 1H,
J4A,4B = 18 Hz, J4A,5 = 1 Hz, 4-HA); 2.76 (dd, B of ABX,
1H, J4A,4B = 18 Hz, J4B,5 = 5 Hz, 4-HB); 4.14 (d, 1H,
d
A
0
J7,8 = 4 Hz, 8-H); 4.51 (dd, 1H, J7;1 ¼ 7 Hz, J7,8 = 4 Hz,
4.3.2. (D-arabino)-4-Benzyloxyhepta-1,6-diene-3,5-diol 9.
Prepared as described for 8, from 6 (1.5 g, 7.3 mmol). Ana-
lytically pure product 9 was obtained after Kugelrohr dis-
tillation (175 °C/0.02 Torr) and recrystallisation from
7-H); 4.64 (s, 2H, CH2Ph); 4.95 (d, 1H, J1,5 = 4 Hz, 1-H);
4.98 (ddd, dX of ABX, 1H, J4B,5 = 5 Hz, J1,5 = 4 Hz,
0
0
0
0
J4A,5 = 1 Hz, 5-H); 5.36 (dd, 1H, J1 ;2 A ¼ 10 Hz, J2 A;2 B
¼
1 Hz, 20-HA); 5.43 (dd, 1H, J1 ;2 B ¼ 18 Hz, J2 A;2 B ¼ 1 Hz,
0
0
0
0
0
0
0
0
hexane. Yield 1.03 g (60%), colourless crystals, mp 50–
20-HB); 6.01 (ddd, 1H, J1 ;2 B ¼ 18 Hz, J1 ;2 B ¼ 10 Hz,
20
0
52 °C, Rf 0.27 (AcOEt–hexanes, 1:2); ½aꢂD ¼ þ45 (c 0.50,
J7;1 ¼ 7 Hz, 10-H); 7.32–7.38 (m, 5H, Ph); 13C NMR
CHCl3); IR (film, cmꢀ1): m 3380, 3089, 3031, 2875, 1725,
1641, 1454; 1H NMR (300 MHz, CDCl3): d 2.38 (br s,
2H, OH); 3.38 (t, 1H, J3,4 = J4,5 = 5 Hz, 4-H); 4.29–4.32
(m, 2H, 3-H, 5-H); 4.69 (s, 2H, CH2Ph); 5.25 (ddd, 2H,
J1A,2 = 10 Hz, J1A,1B = J1A,3 = 1 Hz, 1-HA, 7-HA); 5.41
(ddd, 2H, J1B,2 = 17 Hz, J1A,1B = J1B,3 = 1Hz, 1-HB, 7-
HB); 5.89–6.00 (m, 2H, 2-H, 6-H); 13C NMR (75 MHz,
CDCl3): d 72.2, 72.8 (all d, C-3, C-5), 73.6 (t, CH2Ph),
82.7 (d, C-4), 116.3, 116.7 (all t, C-1, C-7), 128.1, 128.2,
128.6 (all d, Ph), 137.3, 137.6 (all d, C-2, C-6), 137.7 (s,
Ph). Anal. Calcd for C14H18O3 (234.3): C 71.77; H 7.74.
Found: C 71.86; H 7.91.
(75 MHz, CDCl3): d 36.0 (t, C-4); 72.8 (t, CH2Ph); 76.5,
82.0, 82.6, 85.9 (all d, C-1, C-5, C-7, C-8); 119.6 (t, C-20);
127.7, 128.1, 128.5 (all d, Ph); 132.0 (d, C-10); 137.0 (s,
Ph); 175.5 (s, C-3). Anal. Calcd for C15H16O4 (260.3): C
69.22; H 6.20. Found: C 70.02; H 6.51.
4.4.3. Data for (1R,5S,7R,8R)-8-benzyloxy-7-vinyl-2,6-
dioxabicyclo[3.3.0]octan-3-one D-gluco-12. Yield 203 mg
(78%), colourless oil, Rf 0.35 (AcOEt–hexanes, 1:2);
20
½aꢂD ¼ ꢀ29 (c 1.46, CHCl3); IR (film, cmꢀ1): m 3065,
1
3032, 2929, 2871, 1789; H NMR (300 MHz, CDCl3): d
2.72 (d, 2H, J4,5 = 3 Hz, 4-H); 3.95 (dd, 1H, J7,8 = 8 Hz,
0
8-H); 4.32 (dd, 1H, J7,8 = 8 Hz, J7;1 ¼ 6 Hz, 7-H); 4.59
4.3.3. (ribo)-4-Benzyloxyhepta-1,6-diene-3,5-diol 10. Pre-
pared as above from 7 (800 mg, 3.9 mmol). The product
10 was obtained after Kugelrohr distillation (175 °C/
0.02 Torr) Yield 600 mg (66% yield), colourless oil, Rf
0.22 (AcOEt–hexanes, 1:2); IR (film, cmꢀ1): m 3404, 3087,
(d, 1H, J = 12Hz, CH2Ph); 4.67 (d, 1H, J = 12 Hz,
CH2Ph); 4.79 (dd, 1H, J1,5 = 4 Hz, J4,5 = 3 Hz, 5-H); 4.89
(d, 1H, J1,5 = 4 Hz, 1-H); 5.24 (d, 1H, J1 ;2 A ¼ 10 Hz, 20-
0
0
HA); 5.36 (d, 1H, J1 ;2 B ¼ 17 Hz, 20-HB); 5.85 (ddd, 1H,
0
0
J1 ;2 B ¼ 17 Hz, J1 ;2 A ¼ 10 Hz, J7,1 = 6 Hz, 10-H); 7.31–
7.39 (m, 5H, Ph); 13C NMR (75 MHz, CDCl3): d 35.9 (t,
C-4); 72.7 (t, CH2Ph); 77.3, 85.1, 87.0, 87.7 (all d, C-1,
C-5, C-7, C-8); 118.3 (t, C-20); 127.9, 128.2, 128.6 (all d,
Ph); 134.8 (d, C-10); 136.7 (s, Ph); 175.0 (s, C-3). Anal.
Calcd for C15H16O4 (260.3): C 69.22; H 6.20. Found: C
70.15; H 6.43.
0
0
0
0
0
1
3031, 2889, 1454, 1102; H NMR (300 MHz, CDCl3): d
2.58 (br s, 2H, OH); 3.41 (t, 1H, J3,4 = J4,5 = 6 Hz, 4-H);
4.35 (dddd, 2H, J2,3 = J3,4 = 6 Hz, J1A,3 = J1B,3 = 1 Hz,
3-H, 5-H); 4.63 (s, 2H, CH2Ph); 5.24 (ddd, 2H,
J1A,2 = 10 Hz, J1A,1B = J1A,3 = 2 Hz, 1-HA, 7-HA), 5.37
(ddd, 2H, J1B,2 = 17 Hz, J1A,1B = J1B,3 = 1Hz, 1-HB, 7-
HB); 5.93–6.14 (m, 2H, 2-H, 6-H); 7.29–7.36 (m, 5H, Ph);
13C NMR (75 MHz, CDCl3): d 73.6 (d, C-3, C-5), 73.8 (t,
CH2Ph), 83.9 (d, C-4), 116.5 (t, C-1, C-7), 127.9, 128.5
(all d, Ph), 137.4 (d, C-2, C-6), 137.8 (s, Ph). Anal. Calcd
for C14H18O3 (234.3): C 71.77; H 7.74. Found: C 72.03;
H 7.92.
4.4.4. Data for (1R,5S,7R,8S)-8-benzyloxy-7-vinyl-2,6-
dioxabicyclo[3.3.0]octan-3-one D-galacto-13. Yield 23 mg
(9%), colourless oil, Rf 0.13 (AcOEt–hexanes, 1:2);
20
½aꢂD ¼ ꢀ74 (c 0.15, CHCl3); IR (film, cmꢀ1): m 3065,
3032, 2936, 2875, 1789, 1732; 1H NMR (300 MHz, CDCl3):
d 2.76 (d, 2H, J4,5 = 5 Hz, 4-H); 4.10 (dd, 1H, J1,8
=
0
4.4. Pd(II)-catalysed oxycarbonylation of diols 8–10
J7,8 = 5 Hz, 8-H); 4.38 (dd, 1H, J7;8 ¼ J7;1 ¼ 5 Hz, 7-H);
4.55 (d, 1H, J = 12 Hz, CH2Ph); 4.70–4.76 (m, 1H, 5-H);
4.4.1. Typical procedure for PdCl2-catalysed oxycarbonyla-
tion of diols 8–10. A 25 mL-flask with stopcock equipped
with side inlet was charged with AcONa (0.25 g, 3 equiv),
CuCl2 (41 mg, 3 equiv) and PdCl2 (18 mg, 0.1 equiv).
4.78 (d, 1H, J = 12 Hz, CH2Ph); 5,02 (dd, 1H, J1,5 =
0
0
6 Hz, J1,8 = 5 Hz, 1-H); 5.30 (dd, 1H, J1 ;2 A ¼ 10 Hz,
J2 A;2 B ¼ 2 Hz, 20-HA); 5.35 (dd, 1H, J1 ;2 B ¼ 17 Hz,
0
0
0
0
J2 A;2 B ¼ 2 Hz, 20-HB); 6.05 (ddd, 1H, J1 ;2 B ¼ 17 Hz,
0
0
0
0
J1 ;2 A ¼ 10 Hz, J7;1 ¼ 5 Hz, 10-H); 7.31–738 (m, 5H, Ph);
13C NMR (75 MHz, CDCl3): d 36.7 (t, C-4); 73.2. (t,
CH2Ph); 75.9, 78.7, 82.1, 82.2 (all d, C-1, C-5, C-7, C-8);
118.9 (t, C-20); 128.0, 128.1, 128.4 (all d, Ph); 133.4 (d, C-
10); 137.2 (s, Ph); 175.3 (s, C-3). Anal. Calcd for
C15H16O4 (260.3): C 69.22; H 6.20. Found: C 69.12; H 6.28.
0
0
0
4-Benzyloxyhepta-1,6-diene-3,5-diols
8–10
(234 mg,
1.0 mmol) in glacial AcOH (5 mL) were added and the
flask was purged with CO from balloon (residual air was
removed through side inlet with water aspirator). The mix-
ture was vigorously stirred at room temperature until the
colour of the mixture changed from green to pale brown.
The mixture was filtered through a bed of Celite and the fil-
trate was concentrated in vacuo. The crude product was
purified by flash column chromatography (20 g of silica
gel, AcOEt–hexanes, 1:6) to afford lactones 11–14.
4.4.5. Data for ( )-(1S,5R,7R,8R)-8-benzyloxy-7-vinyl-2,6-
dioxabicyclo[3.3.0]octan-3-one (altro-14). Yield 172 mg
(66%), colourless crystals, mp 94–96 °C, Rf 0.23 (AcOEt–
hexanes, 1:2); IR (film, cmꢀ1): m 3065, 3032, 2969, 2873,
1767; 1H NMR (300 MHz, CDCl3): d 2.68 (dd, A of
ABX, 1H, J4A,4B = 19 Hz, J4A,5 = 1 Hz, 4-HA); 2.79 (dd,
B of ABX, 1H, J4A,4B = 19 Hz, J4B,5 = 7 Hz, 4-HB); 3.75
4.4.2. Data for ( )-(1S,5R,7R,8S)-8-benzyloxy-7-vinyl-2,6-
187 mg
dioxabicyclo[3.3.0]octan-3-one
ido-11. Yield
(72%), colourless oil, Rf 0.36 (AcOEt–hexanes, 1:2); IR

44
P. Kapita´n, T. Gracza / Tetrahedron: Asymmetry 19 (2008) 38–44
Syntheses; Negishi, E.-i., Ed.; John Wiley & Sons: New York,
2002; Vol. 2, pp 2351–2375; for reviews see: (d) Muzart, J.
Tetrahedron 2005, 61, 5955–6008; (e) Muzart, J. Tetrahedron
2005, 61, 9423–9463.
(dd, 1H, J7,8 = 8 Hz, J1,8 = 4 Hz, 8-H); 4.33 (dd, 1H,
0
J7;1 ¼ J7;8 ¼ 8 Hz, 7-H); 4.61 (d, 1H, J = 12 Hz, CH2Ph);
4.74 (d, 1H, J = 12 Hz, CH2Ph); 4.84 (ddd, dX of ABX,
1H, J4B,5 = 7 Hz, J1,5 = 4 Hz, J4A,5 = 1 Hz, 5-H); 4.93
3. (a) Orena, M. In Cycloetherification; Helmchen, G., Hoff-
mann, R., Mulzer, J., Eds., 4th ed.; Houben Weyl; Georg
Thieme: Stuttgart, New York, 1995; Vol. E21c, pp 4760–
4817; (b) Elbracht, D. In Addition to Olefinic Double Bonds
Catalysed by Transition Metals; Helmchen, G., Hoffmann,
R., Mulzer, J., Eds., 4th ed.; Houben Weyl; Georg Thieme:
Stuttgart, New York, 1995; Vol. E21c, pp 2488–2734; (c)
Gracza, T.; Haseno¨hrl, T.; Stahl, U.; Ja¨ger, V. Synthesis 1991,
1108–1118; (d) Ja¨ger, V.; Gracza, T.; Dubois, E.; Haseno¨hrl,
0
0
(dd, 1H, J1,5 = J1,8 = 4 Hz, 1-H); 5.27 (d, 1H, J1 ;2
¼
11 Hz, 20-HA); 5.43 (d, 1H, J1 ;2 ¼ 17 Hz, 20-HB); 5.80
0
0
(ddd, 1H, J1 ;2 ¼ 17 Hz, J1 ;2 ¼ 11 Hz, J7;1 ¼ 8 Hz, 10-H);
7.31–7.37 (m, 5H, Ph); 13C NMR (75 MHz, CDCl3): d
36.8 (t, C-4); 72.5 (t, CH2Ph); 76.0, 80.2, 80.7, 82.1 (all d,
C-1, C-5, C-7, C-8); 118.9 (t, C-20); 127.9, 128.1, 128.5
(all d, Ph); 134.6 (d, C-10); 137.2 (s, Ph); 175.4 (s, C-3).
Anal. Calcd for C15H16O4 (260.3): C 69.22; H 6.20. Found:
C 69.44; H 6.39.
0
0
0
0
0
T.; Hummer, W.; Kautz, U.; Kirschbaum, B.; Lieberknecht,
¨
A.; Remen, L.; Shaw, D.; Stahl, U.; Stephan, O. In Pd(II)-
catalyzed Carbonylation of Unsaturated Polyols and Aminop-
olyols; Helmchen, G., Dibo, J., Flubacher, D., Wiese, B.,
Eds.; Organic Synthesis via Organometallics OSM 5; Vieweg:
Braunschweig, 1997; pp 331–360; (e) Wolfe, J. P. Eur. J. Org.
Chem. 2007, 571–582.
4.5. Typical procedure for the asymmetric oxycarbonylation
of diols 8 and 10 with (L*)Pd(OAc)2, (L*)Pd(OCOCF3)2
Chiral ligand (0.15 mmol) in CH2Cl2 (1 mL) was added to
the solution of Pd(OCOCF3)2, (0.05 mmol, 0.05 equiv) in
CH2Cl2 (1 mL). The mixture was stirred for 15 min to give
a clear solution. Substrate (1.0 mmol) in CH2Cl2 (1 mL), p-
benzoquinone (4.0 equiv) in CH2Cl2 (1 mL) and glacial
AcOH (0.5 mL) were added. The flask was purged with
CO from a balloon and the reaction mixture was vigor-
ously stirred until the deposition of black palladium was
observed. The solvent was evaporated and the crude prod-
uct purified by flash column chromatography.
4. Semmelhack, M. F.; Bodurow, Ch.; Baum, M. Tetrahedron
Lett. 1984, 25, 3171–3174.
5. Tamaru, Y.; Kobayashi, T.; Kawamura, S.-i.; Ochiai, H.;
Hojo, M.; Yoshida, Z.-i. Tetrahedron Lett. 1985, 26, 3207–
3210.
6. (a) Kraus, G. A.; Li, J. J. Am. Chem. Soc. 1993, 115, 5859–
5860; (b) Kraus, G. A.; Li, J.; Gordon, M. S.; Jensen, J. H. J.
Org. Chem. 1995, 60, 1154–1159; (c) Gracza, T.; Ja¨ger, V.
Synlett 1992, 191–193; (d) Gracza, T.; Ja¨ger, V. Synthesis
´
1994, 1359–1368; (e) Babjak, M.; Kapitan, P.; Gracza, T.
Tetrahedron Lett. 2002, 43, 6983–6985; (f) Babjak, M.;
´
Kapitan, P.; Gracza, T. Tetrahedron 2005, 61, 2471–2479;
Acknowledgements
´
(g) Dixon, D. J.; Ley, S. V.; Gracza, T.; Szolcsanyi, P. J.
Chem. Soc., Perkin Trans. 1 1999, 839–841; (h) Boukouvalas,
J.; Fortier, G.; Radu, I.-I. J. Org. Chem. 1998, 63, 916–917; (i)
Paddon-Jones, G. C.; McErlean, S. P.; Hayes, P.; Moore, C.
J.; Konig, W. A.; Kitching, W. J. Org. Chem. 2001, 66, 7487–
7495; (j) Hayes, P. Y.; Kitching, W. J. Am. Chem. Soc. 2002,
124, 9718–9719; (k) Semmelhack, M. F.; Shanmugam, P.
Tetrahedron Lett. 2000, 41, 3567–3571; (l) Semmelhack, M.
F.; Hooley, R. J.; Kraml, Ch. M. Org. Lett. 2006, 8, 5203–
5206.
This work was supported by Slovak Grant Agencies
(VEGA, Slovak Academy of Sciences and Ministry of Edu-
cation, Bratislava, Project No. 1/3549/06, and APVV, Bra-
tislava, Project No. APVV-20-000305). The authors are
grateful to Professor Marko D. Mihovilovic (Vienna Uni-
versity of Technology) for his help with the determination
of enantiomeric purity.
´
7. Kapitan, P.; Gracza, T. Arkivoc 2008, viii, 8–17.
8. Holland, D.; Stoddart, J. F. Carbohydr. Res. 1982, 100, 207–
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