Addition of allylstannanes to an oxy-stabilized carbenium ion on a 1,7-dioxaspiro[5.5]undecane ring system

Article abstract of DOI:10.1039/a707607j

The nucleophilic addition of allylstannanes to (2R*,5S*,6S*)-2-acetoxy-5-benzyloxy-1,7-dioxaspiro-[5.5] undecane 1 has been studied. The optimum conditions involve the use of trimethylsilyl trifluoromethanesulfonate in dichloromethane at -78°C. In the exa

Full text of DOI:10.1039/a707607j

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Addition of allylstannanes to an oxy-stabilized carbenium ion on a
1
,7-dioxaspiro[5.5]undecane ring system
,
Margaret A. Brimble,* † Fares A. Fares and Peter Turner
School of Chemistry, University of Sydney, Camperdown, NSW 2006, Australia
The nucleophilic addition of allylstannanes to (2R*,5S*,6S*)-2-acetoxy-5-benzyloxy-1,7-dioxaspiro-
[
5.5]undecane 1 has been studied. The optimum conditions involve the use of trimethylsilyl trifluoro-
methanesulfonate in dichloromethane at ؊78 ЊC. In the examples studied, substitution of the acetoxy
group at C-2 proceeds from an axial direction, however, subsequent ring flipping of the substituted
ring occurs as well affording allylated products in which the substituents at both C-2 and C-5 are
equatorial.
The 1,7-dioxaspiro[5.5]undecane ring system is an important
structural feature in many biologically active compounds such
as the polyether antibiotics, marine and plant toxins, insect
pheromones and the antiparasitic agents—the milbemycins and
tained an axial benzyloxy substituent at C-5. Upon treatment
with acid, spiroacetal 1 would undergo thermodynamically
controlled ring opening/ring closure to afford the more stable
spiroacetal in which the benzyloxy group adopts a more favour-
able equatorial position. Monitoring the stereochemistry at C-5
would therefore provide evidence as to whether addition of the
allylstannane to the C-2 centred oxocarbenium ion preceded
or followed opening of the spiroacetal ring.
1
the avermectins. More recently cytotoxic and/or antineoplastic
marine organism constituents such as the highly potent spongi-
2
3
statins and the spirolides have been found to contain spiro-
acetals bearing an allyl unit attached to the terminus of the
spiroacetal ring system. We were therefore interested in develop-
ing methods to append an allyl unit to C-2 of the 1,7-dioxaspiro-
Hydration of alkene 2 followed by acetylation (Scheme 2)
[
5.5]undecane ring system.
O
The majority of synthetic approaches to substituted spiro-
O
O
i
1
acetals have involved incorporation of the appropriate
substituents into dihydroxy ketone precursors (or synthetic
equivalents thereof) which then undergo cyclization to a
spiroacetal ring system. Our approach reported herein focuses
on further functionalization of a basic 1,7-dioxaspiro[5.5]-
undecane framework via stereocontrolled addition of allylstan-
nanes to a C-2 centred oxocarbenium ion. A related approach
+
O
OAc
O
O
OAc
BnO
OBn
OBn
3
32%
2
1 48%
O
OAc
+
O
4
by Mead using allylsilanes as the nucleophilic component has
recently been reported and prompted us to publish our work in
this area.
OBn
4
4%
Whereas Mead’s work focused on the addition of allylsilanes
to a C-2 centred spirooxocarbenium ion derived from a 2-
methoxy-1,7-dioxaspiro[5.5]undecane ring system our attention
focused on the use of a 2-acetoxyspiroacetal to generate the
oxocarbenium ion (Scheme 1). In an effort to effect selective
Scheme 2 Reagents and conditions: i, THF, H O, p-TsOH, room temp.,
2
then Ac O, Et N, DMAP (cat.), CH Cl
2
3
2
2
afforded 2-acetoxy spiroacetals 1 and 3 with an equatorial
acetate group at C-2 as major products, together with spiro-
acetal 4 where the acetate group was axial, as a minor product.
The methine proton, H-5, in spiroacetal 1 resonated as a triplet
at δ = 3.15 ppm with the magnitude of the coupling constant,
J = 2.4 Hz, establishing that the benzyloxy substituent assumed
an axial position whilst H-2 resonated as a double doublet at
δ = 5.69 ppm with the coupling constants, J = 9.7 and 2.8 Hz,
establishing that the acetate group occupied an equatorial pos-
ition. The substrate required for the present work, namely
spiroacetal 1, was easily separated from the other spiroacetals 3
and 4 by flash chromatography and the stereochemistry was
confirmed by X-ray crystallography (Fig. 1).
OAc
O
O+
Lewis
acid
Bu3Sn
O
O
O
O
Scheme 1
reaction of the lactol acetate leaving the spiroacetal intact, we
also chose to use allylstannanes which being more nucleophilic
The optimum conditions for reaction of spiroacetal 1 with
allyltributylstannane (entry 1, Table 1) involved the use of
TMSOTf as the Lewis acid in dichloromethane at Ϫ78 ЊC using
5
than allylsilanes would require milder conditions for gener-
ation of the electrophilic species. Whilst the use of glycosyl
acetates as precursors to oxocarbenium ions in carbohydrate
chemistry is well established, use of anomeric spiroacetal acet-
ates in a spirodipyran system has not been studied. The gener-
3
equivalents of the stannane. Under these conditions the
equatorial C-2 allylated spiroketal 5a was isolated in 72% yield.
The double doublet at δ = 3.26 ppm with coupling constants
J = 11.1 and 4.9 Hz, assigned to H-5, confirmed that the benzyl-
oxy group at C-5 now occupied a more stable equatorial
position.
4,6
ation of spirooxocarbenium ion intermediates is also rare.
In order to probe the stereochemical course of these reac-
tions attention focused on the use of spiroacetal 1 which con-
1
Whilst the H NMR data readily assigned the benzyloxy
†
E-Mail: brimble_m@chem.usyd.edu.au
and allyl groups to equatorial positions, the conformation
J. Chem. Soc., Perkin Trans. 1, 1998
677

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Table 1 Reaction of spiroacetal 1 with allylstannanes and TMSOTf in
CH Cl at Ϫ78 ЊC
2
2
Entry
Allylstannane
Product(s)
Time
Yield (%)
1
2
3
4
5
6
7
6a
6b
6c
6d
6e
6f
5a
5b
5c
5d
5e
5f
8 h
8 h
10 h
16 h
16 h
16 h
6 h
72
67
52
37
65
28
58
6g
5g
i
5
a
RO
O
O
OBn
7
8
R = H
R = p-NO2C6H4CO
ii
iii
OBn
1
3
O
5
7
O
7
+
5
O
O
3
OBn
O
O
1
1
1a
11b
Scheme 3 Reagents and conditions: i, BH ؒTHF, NaOH, H O , 0 ЊC to
3
2
2
room temp., 68%; ii, p-NO C H COCl, Et N, DMAP (cat.), CH Cl ,
2
6
4
3
2
2
8
9%; iii, PhI(OAc) , I , cyclohexane, room temp., 66%
2 2
2
3
Fig. 1 A labelled ORTEP projection of 1 with thermal ellipsoids
depicted at the 25% level
spirocentre had changed and did not represent the most stable
arrangement of O-1 and O-7 as predicted by the anomeric
7
effect.
O
O
TMSOTf
The isolation of allylated spiroacetal 5a as the only product
from the addition of allylstannane 6a to spiroacetal 1 in the
presence of TMSOTf can be rationalized by axial approach of
the stannane onto the oxycarbenium ion, followed by ring flip-
ping of the disubstituted A ring in order to relieve unfavourable
2
+
O
O
OAc
78 o
C
–
5
OBn
OBn
1
R2
1
,3-diaxial interactions between the allyl group and 8-CH . This
2
Bu3Sn
R1
ring flip proceeded at the expense of a stabilizing anomeric
effect at the spirocentre.
R3
6
Reaction of spiroacetal 1 with more functionalized allyl-
stannanes (entries 2–7, Table 1) also afforded spiroacetal prod-
ucts in which both the C-2 allyl group and the C-5 benzyloxy
group occupied equatorial positions. It is also noted however,
that tetrahydropyran products resulting from addition of the
allylstannane to the spirocentre and C-2 (e.g. 9) were not
observed.
R2
O
R1 R2
R1
O
invert ring A
O
R3
BnO
O
R3
OBn
rotate 180o
In an effort to promote selective reaction at C-2, spiroacetal
1
0 which bears an acetate group at C-3 was prepared with the
anticipation that this additional acetate group would stabilize
the incipient oxycarbenium ion formed at C-2 by neighbouring
group participation. It was also of interest as to whether the
C-3 acetate group had any effect on the stereochemical outcome
of the reaction. We were, however, somewhat disappointed to
find that using a variety of Lewis acids the successful addition
of allylsilanes and allylstannanes to 10 was not realized despite
extensive investigation. Spiroacetal 10 tended to decompose to
a complex mixture of products and we attribute this to the
increased steric hindrance by the neighbouring acetate group
towards attack of the allylating agent on the C-2 oxocarbenium
ion derived from 10.
R3
O
O
OBn
R1 R2
5
1
2
3
1
2
3
a R = R = R = H
e R = Me; R = R = H
1
2
3
b R = R = H; R = Me
1
3
2
t
f R = R = H; R = OSiBu Me2
1
2
3
c R = R = Me; R = H
1
2
3
t
g R = R = H; R = CH2CH2OSiBu Ph2
1
2
3
d R = C6H5; R = R = H
1
2
3
h R = R = H; R = CH2CH2OH
that the spiroacetals adopted needed addressing. In order to
address this issue spiroacetal 5a underwent hydroboration with
diborane in THF providing alcohol 7 which was then converted
to its p-nitrobenzoate derivative 8 in order to provide crystals
suitable for X-ray diffraction. The resultant crystal structure for
The formation of oxaspiro rings by H-abstraction promoted
by hypervalent iodine reagents has been applied to the synthesis
of the bis-spiroacetal moiety of the polyether antibiotic salino-
8
mycin and in the synthesis of chiral spiroacetals from carbo-
9
hydrates. In the present work the synthetic utility of the C-2
8
(Fig. 2) confirmed that although the substituents at C-5 and
allylated spiroacetals was demonstrated by the conversion of
allylspiroacetals 5a and 5g to the tricyclic bis-spiroacetals 11
C-2 adopted equatorial positions, the conformation of the
6
78
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
2
3
Fig. 2 A labelled ORTEP projection of 8 with thermal ellipsoids depicted at the 25% level
interactions between the methylene groups at C-5 and C-13.
A similar conformation was observed for an analogous bis-
spiroacetal.
In summary the nucleophilic addition of allylstannanes to an
oxy-stabilized carbenium ion on a 1,7-dioxaspiro[5.5]undecane
ring system has been investigated. Placement of an axial benzyl-
oxy group at C-5 on the spiroacetal ring allowed the stereo-
chemical course of these reactions to be studied. The allylated
spiroacetals thus formed can be readily transformed into tri-
cyclic bis-spiroacetals.
OBn
O
10
O
OAc
OAc
O
OH
OBn
9
10
BnO
BnO
O
1
4
14
9
O
9
O1
O
7
O
7
1O
1
3
5
Experimental
Mps were determined on a Kofler hot-stage apparatus and are
uncorrected. IR spectra were recorded on a Perkin-Elmer 1600
Fourier Transform infra-red spectrophotometer as a thin film
between sodium chloride plates. Elemental analyses were
performed at the Microanalytical Laboratory, University of
1
2a
12b
and 12 respectively. Thus, hydroboration of 5a afforded alcohol
in 68% yield which upon treatment with iodobenzene diac-
7
etate and iodine underwent oxidative cyclization to a 1:1.5 mix-
ture of bis-spiroacetals 11a and 11b in 66% yield (Scheme 3).
The cis and trans isomers of bis-spiroacetal 11 were readily
separated by flash chromatography and the stereochemistry
established by NMR spectroscopy.
The H NMR spectrum of 11a exhibited a double doublet at
δ 3.25 ppm (J = 7.5 and 4.4 Hz) indicating an equatorial dis-
1
New South Wales, Sydney, Australia. H NMR spectra were
recorded in deuteriochloroform on a Bruker AC 200 (200.13
13
MHz) at ambient temperature. All J values are given in Hz.
C
NMR spectra were recorded on a Bruker AC 200 (50.3 MHz),
spectrometer at ambient temperature with complete proton
decoupling. Data are expressed in parts per million downfield
shifted from tetramethylsilane as an internal standard and
1
position of the benzyloxy group at C-13. For bis-spiroacetal
1
1b this same proton resonates as a double doublet at δ 3.26
reported as position (δ ). Low resolution mass spectra were
C
ppm (J = 3.2 and 1.5 Hz) indicating an axial disposition for the
benzyloxy group in this case. The major isomer 11b exhibits
three anomeric effects whilst 11a exhibits only two anomeric
effects. Further evidence for formation of bis-spiroacetals 11a
and 11b was indicated in the IR spectra which lacked an
hydroxy group absorption and by the observation of a second
quaternary carbon at δ 106.2 and 107.2 ppm respectively,
characteristic of the newly formed spirocentre. Similar spectral
characteristics have been reported in a related system by Suarez
recorded on a VG70-250S, a VG70-SD or a AEI model MS902
double focusing magnetic sector mass spectrometer operating
with an ionization potential of 70 eV (EI, DEI, CI and DCI).
High resolution mass spectra were recorded at a nominal reso-
lution of 5000 or 10 000 as appropriate. Major fragments are
given as percentages relative to the base peak and assigned
where possible. Ionization methods employed were (i) electron
impact (EI), (ii) desorption electron impact (DEI), (iii) chemical
ionization with ammonia as reagent gas (CI) and (iv) desorp-
tion chemical ionization (DCI) with methane as reagent gas.
Low resolution chemical ionization mass spectra were also
recorded on a Hewlett Packard 5989A mass spectrometer using
methane as reagent gas with the sample dissolved in methanol.
Flash chromatography was performed using Merck Kieselgel
60 or Riedel-de Haen Kieselgel (both 230–400 mesh) with the
indicated solvents. Thin layer chromatography (TLC) was per-
formed using 0.2 mm thick precoated silica gel plates (Merck
Kieselgel 60 F254 or Riedel-de Haen Kieselgel S F254). Com-
pounds were visualized by ultraviolet fluorescence or by stain-
ing with iodine or vanillin in methanolic sulfuric acid.
9a
et al.
Whilst cyclization of 7 led to formation of a 1,6,8-tri-
oxadispiro[4.1.5.3]pentadecane ring system the homologous
1
by oxidative cyclization of alcohol 5h. Treatment of alcohol 5h
obtained after desilylation of allylspiroacetal 5g, with iodo-
benzene diacetate and iodine afforded a 1.33:1 mixture of bis-
,7,9-trioxadispiro[5.1.5.3]hexadecane ring system was formed
1
spiroacetals 12a and 12b in 70% yield. Once again the H NMR
spectra of these isomers allowed ready assignment of stereo-
chemistry. Thus, 14-H resonated as a double doublet at δ 3.46
ppm (J = 4.7 and 3.4 Hz) in the cis isomer 12b which was sig-
nificantly deshielded relative to the same proton in the trans
isomer 12a which resonated at δ 3.26 ppm (J = 6.8 and 4.3 Hz)
due to its close proximity to O-1. The vicinal coupling constants
observed for 14-H in 12b suggest that the central ring adopts a
skew-boat conformation in order to relieve unfavourable steric
(5S*,6S*)-5-Benzyloxy-1,7-dioxaspiro[5.5]undec-2-ene 2
To a suspension of sodium hydride (353 mg, 8.82 mmol) in dry
3
tetrahydrofuran (15 cm ) at 0 ЊC was added dropwise a solution
11
of (5S*,6S*)-1,7-dioxaspiro[5,5]undec-2-en-5-ol (1.25 g, 7.35
J. Chem. Soc., Perkin Trans. 1, 1998
679

View Article Online
3
mmol) in dry tetrahydrofuran (25 cm ) under an argon atmos-
67.49; H, 7.71. C H O requires C, 67.47; H, 7.55%);
18
24
5
Ϫ1
phere and the resultant suspension allowed to stir at 0 ЊC for
νmax(CHCl )/cm 2948m, 2872m (CH), 1747s (C᎐O, acetate),
3
1
h. Benzyl bromide (1.38 g, 8.1 mmol) was added, the reaction
mixture allowed to warm to room temperature and stirred for
4 h. After quenching with sodium dihydrogen phosphate solu-
1454, 1371, 1236, 1071, 1045, 980; δ (200 MHz; CDCl ) 1.20–
H
3
2.12 (10H, m, 5 × CH ), 2.10 (3H, s, Ac), 3.24 (1H, dd, J
2
5ax,4ax
2
9.2, J5ax,4eq 5.8, 5 -H), 3.77–3.85 (1H, m, 8 -H), 4.01–4.14 (1H,
a
x
e
q
3
tion (15 cm , 10% w/v), the reaction mixture was extracted with
m, 8 -H), 4.50 (1H, d, J 12.2, OCH H Ar), 4.67 (1H, d, J
ax
A,B
A
B
B,A
3
3
ethyl acetate (3 × 100 cm ), washed with water (40 cm ) and
dried over sodium sulfate. Removal of the solvent under
reduced pressure gave a pale yellow oil which was purified by
flash chromatography using hexane–ethyl acetate (9:1) as elu-
ent to afford the title compound 2 (1.59 g, 83%) as a colourless
oil (Found: C, 74.23; H, 8.08. C H O requires C, 73.81; H,
12.2, OCH H Ar), 5.95 (1H, dd, J
10.0, J2ax,3eq 2.4, 2 -H),
2ax,3ax ax
A
B
7.19–7.41 (5H, m, Ar-H); δ (50 MHz; CDCl ) 18.0, 21.8, 24.6,
C
3
29.2, 30.4 (CH , C-9, C-10, C-11, C-4 and C-3), 21.2 (CH , Ac),
2
3
61.6 (CH , C-8), 71.6 (CH , OCH Ar), 77.8 (CH, C-5), 89.0
2
2
2
(CH, C-2), 99.0 (quat., C-6), 127.7, 128.2, 128.3 (CH, Ar-C),
138.3 (quat., Ar-C), 169.5 (quat., C᎐O); m/z (CI, CH ) 319
1
6
20
3
4
Ϫ1
7
1
.75%); νmax(CHCl )/cm 2946s, 2872s (CH), 1654m (C᎐C),
(M Ϫ H, 0.1%), 261 (M Ϫ OAc, 100), 153 (M Ϫ OAc Ϫ OBn,
74) and 61 (33).
3
601, 1454, 1228, 1203, 1099, 1029, 908, 792; δ (200 MHz;
H
CDCl ) 1.23–2.32 (8H, m, 4 × CH ), 3.40–3.44 (1H, m, 5 -H),
(iii) (2S*,5S*,6S*)-2-Acetoxy-5-benzyloxy-1,7-dioxaspiro-
[5.5]undecane 4 (35 mg, 4.2%) as a colourless oil (Found: C,
67.50; H, 7.82. C H O requires C, 67.47; H, 7.55%);
3
2
eq
3
.60–3.69 (1H, m, 8 -H), 3.76–3.89 (1H, m, 8 -H), 4.50 (1H, d,
eq
ax
JA,B 12.2, OCH H Ar), 4.67 (1H, d, J
12.2, OCH H Ar),
A
B
B,A
A
B
18 24
5
Ϫ1
4
.70 (1H, m, 3-H), 6.27–6.32 (1H, m, 2-H), 7.25–7.38 (5H, m,
νmax(CHCl )/cm 2947m, 2870m (CH), 1730s (C᎐O, acetate),
3
Ar-H); δ (50 MHz; CDCl ) 17.9, 21.7, 24.9, 30.4 (CH , C-9,
1453, 1255, 1364, 1064, 1182, 1228; δ (200 MHz; CDCl ) 1.20–
C
3
2
H
3
C-10, C-11 and C-4), 61.3 (CH , C-8), 71.1 (CH , OCH Ar),
2.21 (10H, m, 5 × CH ), 2.09 (3H, s, Ac), 3.32 (1H, dd, J 3.0
2
2
2
2
7
1
4.3 (CH, C-5), 96.2 (quat., C-6), 98.7 (CH, C-3), 127.5, 127.8,
and 1.1, 5 -H), 3.57–3.65 (1H, m, 8 -H), 3.72–3.85 (1H, m,
eq
eq
28.1, 128.6, 128.8 (CH, Ar-C), 138.1 (quat., Ar-C), 139.7 (CH,
8ax-H), 4.48 (1H, d, JA,B 12.0, OCH H Ar), 4.66 (1H, d, J
A
B
B,A
ϩ
C-2); m/z 260 (M , 8%), 204 (38), 175 (32), 113 (100) and 91
12.0, OCH H Ar), 6.15 (1H, d, J
2.43, 2 -H), 7.18–7.39
2eq,3ax eq
A
B
(
C H , 50).
(5H, m, Ar-H); δ (50 MHz; CDCl ) 17.7, 18.0, 23.2, 25.0, 32.6
7
7
C
3
(
CH , C-9, C-10, C-11, C-4 and C-3), 21.2 (CH , Ac), 62.0
2 3
(
5
2R*,5S*,6S*)-, (2R*,5R*,6S*)- and (2S*,5S*,6S*)-2-Acetoxy-
-benzyloxy-1,7-dioxaspiro[5.5]undecane 1, 3 and 4
To solution of (5R*,6R*)-5-benzyloxy-1,7-dioxaspiro-
5.5]undec-2-ene 2 (680 mg, 2.62 mmol) in a mixture of THF–
(CH , C-8), 71.8 (CH , OCH Ar), 76.8 (CH, C-5), 92.1 (CH,
2 2 2
C-2), 97.5 (quat., C-6), 127.7, 128.2, 128.3 (CH, Ar-C), 138.2
(quat., Ar-C), 171.3 (quat., C᎐O); m/z (CI, CH ) 319 (M Ϫ H,
a
᎐
4
[
0.1%), 261 (M Ϫ OAc, 64), 153 (M Ϫ OAc Ϫ OBn, 100), 107
3
H O (4:1) (30 cm ) was added toluene-p-sulfonic acid (20 mg).
(17) and 91 (C H , 26).
2
7
7
The mixture was stirred and heated to 35–40 ЊC for 48 h. Pro-
gress of the reaction was monitored by TLC. Additional
amounts of toluene-p-sulfonic acid were added if the progress
was too slow. The mixture was neutralized by the addition of a
General procedure for the preparation of the stannanes (6b–e)
The appropriate allyl chloride (6 mmol) was added to a mixture
3
of tributyltin chloride (1.36 cm , 1.63 g, 5 mmol), a crystal of
3
iodine and magnesium turnings (156 mg, 6.5 mmol) in THF (10
saturated solution of sodium hydrogen carbonate (10 cm ). The
3
12
1
cm ) using the procedure reported by Naruta et al. The H
aqueous layer was extracted with dichloromethane (3 × 40
3
NMR data were in agreement with those reported in the
cm ). The combined organic layers were washed with brine (20
12,13,14
3
literature.
cm ) and dried over sodium sulfate. Removal of the solvent
under reduced pressure gave a colourless oil which was used
directly in the next step.
1
-(tert-Butyldimethylsilyloxy)-3-(tributylstannyl)propene 6f
The title compound was prepared from tert-butyldimethyl-
silylallyl ether (2.58 g, 15 mmol) and tributyltin chloride (4.47
cm , 16.6 mmol) following the procedure by Keck et al. as a
colourless oil (3.9 g, 60%). The H and C NMR spectra were
To a solution of the above mixture of hemiacetals in dichloro-
3
methane (30 cm ) at room temperature, was added dry triethyl-
3
15
amine (398 mg, 3.93 mmol), followed by acetic anhydride (321
mg, 3.14 mmol) and 4-dimethylaminopyridine (5 mg) and the
reaction mixture was stirred, gently at room temperature for 3 h
or until no starting material could be detected by TLC. The
1
13
15
in agreement with those reported in the literature.
4
-(tert-Butyldiphenylsilyloxy)-2-[(tributylstannyl)methyl]but-1-
3
reaction mixture was quenched with water (10 cm ), extracted
ene 6g
3
with dichloromethane (2 × 50 cm ) and dried over sodium
The title compound was prepared in 70% yield as a colourless
oil according to the method reported by Weigand et al. The
spectroscopic data were in agreement with those reported in the
literature.
sulfate. Removal of the solvent under reduced pressure gave a
colourless oil which was purified by flash chromatography using
hexane–ethyl acetate (8.5:1.5) as eluent to afford:
13
13
(
i)
5.5]undecane 1 (400 mg, 47.8%) as colourless needles, mp 75–
6 ЊC (from hexane) (Found: C, 67.48; H, 7.86. C H O
(2R*,5S*,6S*)-2-Acetoxy-5-benzyloxy-1,7-dioxaspiro-
[
7
General procedure for allylation
The lactol acetate 1, the appropriate stannane (2.5–3 equiv.)
and powdered molecular sieves (200 mg, 4 Å) in dichloro-
18
24
5
Ϫ1
requires C, 67.47; H, 7.55%); νmax(CHCl )/cm 2947m, 2869m
3
3
(
CH), 1740s (C᎐O, acetate), 1450, 1368, 1087, 1206; δ (200
methane (8 cm ) were placed under an atmosphere of dry
᎐
H
MHz; CDCl ) 1.23 (1H, ddd, J
13.4, J11ax,10ax 13.4 and
argon. The solution was cooled to Ϫ78 ЊC, a catalytic quantity
of trimethylsilyl trifluoromethanesulfonate was added and the
reaction mixture was stirred whilst warming to room temper-
ature. Progress of the reaction was monitored by TLC. After
the reaction was complete, the solvent was removed in vacuo,
the residue taken up in diethyl ether and washed once with pH 7
3
11ax,11eq
J11ax,10eq 4.3, 11 -H), 1.40–2.22 (9H, m, 4 × CH and 11 -H),
ax
2
eq
2
.09 (3H, s, Ac), 3.15 (1H, t, J 2.4, 5 -H), 3.59–3.71 (1H, m,
eq
8eq-H), 4.01–4.14 (1H, m, 8 -H), 4.45 (1H, d, J
12.1,
A,B
ax
OCH H Ar), 4.66 (1H, d, J
12.1, OCH H Ar), 5.96 (1H,
A
B
B,A
A B
dd, J2ax,3ax 9.7, J2ax,3eq 2.8, 2 -H), 7.20–7.39 (5H, m, Ar-H);
ax
3
δ (50 MHz; CDCl ) 17.9, 21.0, 23.9, 25.0, 31.5 (CH , C-9, C-10,
phosphate buffer (10 cm ). The ether layer was added to a
C
3
2
C-11, C-4 and C-3), 21.3 (CH , Ac), 61.2 (CH , C-8), 71.2 (CH ,
saturated aqueous solution of potassium fluoride and the mix-
ture was stirred vigorously for 30 min, whereupon tributyl-
tin() fluoride precipitated. After removal of the salts by
filtration, the organic phase was dried over anhydrous sodium
sulfate and concentrated to give an oil which was purified by
flash chromatography using hexane–ethyl acetate as eluent to
give the allylated products:
3
2
2
OCH Ar), 74.7 (CH, C-5), 89.6 (CH, C-2), 99.5 (quat., C-6),
2
1
27.6, 127.9, 128.2 (CH, Ar-C), 138.2 (quat., Ar-C), 169.8
(
(
quat., C᎐O); m/z (CI, CH ) 319 (M Ϫ H, 0.1%), 261
᎐
4
M Ϫ OAc, 100), 153 (M Ϫ OAc Ϫ OBn, 54) and 61 (18).
ii) (2R*,5R*,6S*)-2-Acetoxy-5-benzyloxy-1,7-dioxaspiro-
5.5]undecane 3 (265 mg, 31.6%) as a colourless oil (Found: C,
(
[
6
80
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
(
2R*,5S*,6S*)-2-(Prop-2Ј-enyl)-5-benzyloxy-1,7-dioxaspiro-
(2R*,5S*,6S*,1ЈR*)- and (2R*,5S*,6S*,1ЈS*)-2-(1Ј-Phenyl-
[
5.5]undecane 5a
prop-2Ј-enyl)-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 5d
The title compound 5d was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (120 mg,
0.375 mmol) and (E)-1-phenyl-3-(tributylstannyl)prop-1-ene 6d
as a colourless oil (53 mg, 37%) (Found: C, 79.06; H, 7.99.
The title compound 5a was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (183 mg,
0
7
8
1
0
.57 mmol) and allyltributyltin 6a as a colourless oil (124 mg,
2%) (Found: C, 75.65; H, 9.04. C H O requires C, 75.45; H,
1
9
26
3
Ϫ1
Ϫ1
.67%); νmax(CHCl )/cm 3066w (᎐CH), 2947s, 2876m (CH),
C H O requires C, 79.33; H, 7.99%); νmax(CHCl )/cm
3
25 30
3
3
641w (C᎐C), 1454, 1357, 1224, 1081; δ (200 MHz; CDCl )
3006m, 2928s, 2855m (CH), 1601w (C᎐C), 1454, 1099, 1001;
δ (200 MHz; CDCl ) 0.84–1.95 (10H, m, 5 × CH ), 2.05–2.19
᎐
H
3
.90–2.12 (10H, m, 5 × CH ), 2.14–2.42 (2H, m, CH CH᎐
2
2
H
3
2
CH ), 3.26 (1H, dd, J
11.1, J5ax,4eq 4.9, 5 -H), 3.36–3.49
(1H, m, CHPh), 3.12 (1H, t, J 2.6, 5 -H), 3.36 (1H, t, J 8.0, 2 -
2
5ax,4ax
ax
e
q
a
x
(
1H, m, 2 -H), 3.64–3.78 (1H, m, 8 -H), 3.96–4.18 (1H, m,
H), 3.48–3.54 (1H, m, 8 -H), 3.75–3.86 (1H, m, 8 -H), 4.41
eq ax
ax
eq
8ax-H), 4.60 (1H, d, JA,B 12.1, OCH H Ar), 4.85 (1H, d, J
(1H, d, JA,B 12.2, OCH H Ar), 4.63 (1H, d, J 12.2, OCHA-
A
B
B,A
A B B,A
1
2.1, OCH H Ar), 5.02–5.12 (2H, m, CH᎐CH ), 5.79–6.00
H Ar), 5.00 (1H, dt, J3Јb,2Ј17.0, J3Јb,3Јa 1.5, 3Ј -H), 5.11 (1H, dt,
A
B
᎐
2
B
b
(
1H, m, CH᎐CH ), 7.15–7.45 (5H, m, Ar-H); δ (50 MHz;
J3Јa,2Ј 10.4, J3Јa,3Јb 1.5, 3Ј -H), 6.33 (1H, ddd, J
17.1, J2Ј,3Јa 10.1
᎐
2
C
a
2Ј,3Јb
CDCl ) 17.5, 22.4, 25.5, 26.6, 30.5 (CH , C-9, C-10, C-11, C-4
and J2Ј,1Ј 7.5, 2Ј-H), 7.10–7.39 (10H, m, Ar-H); δ (50 MHz;
3
2
C
and C-3), 40.4 (CH, CH CH᎐CH ), 61.4 (CH , C-8), 71.6 (CH,
CDCl ) 18.2, 22.2, 23.6, 25.4, 32.2 (CH , C-9, C-10, C-11, C-4
2
2
2
3
2
C-2), 72.6 (CH , OCH Ar), 79.8 (CH, C-5), 99.9 (quat., C-6),
and C-3), 55.5 (CH, CHPh), 60.4 (CH , C-8), 70.9 (CH ,
2
2
2
2
1
16.5 (CH , CH᎐CH ), 127.3, 127.7, 128.2 (CH, Ar-C), 135.3
OCH Ar), 72.2 (CH, C-2), 75.3 (CH, C-5), 96.9 (quat., C-6),
2
2
2
ϩ
(
CH, CH᎐CH ), 139.2 (quat., Ar-C); m/z (CI, CH ) 303 (MH ,
116.1 (CH , CH᎐CH ), 126.4, 127.5, 128.0, 128.2, 128.3, 128.6
᎐
2
4
2 2
1
1
4%), 285 (M Ϫ OH, 16), 261 (M Ϫ C H , 16), 195 (M Ϫ OBn,
(CH, Ar-C), 139.0 (quat., Ar-C), 139.2 (CH, CH᎐CH ); m/z
᎐
2
ϩ
3
5
00) and 91 (C H , 24).
(CI, CH ) 379 (MH , 9%), 271 (M Ϫ OBn, 18), 261 (M Ϫ
7
7
4
C H , 18), 107 (BnO, 25) and 91 (C H , 11).
9
9
7
7
(
2R*,5S*,6S*)-2-(2Ј-Methylprop-2Ј-enyl)-5-benzyloxy-1,7-
(
2R*,5S*,6S*,1ЈR*)- and (2R*,5S*,6S*,1ЈS*)-2-(1Ј-Methyl-
dioxaspiro[5.5]undecane 5b
The title compound 5b was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (85 mg,
prop-2Ј-enyl)-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 5e
The title compound 5e was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (100 mg,
0
.27 mmol) and 2-methyl-3-(tributylstannyl)prop-1-ene 6b as a
0
.31 mmol) and (E)-4-(tributylstannyl)but-2-ene 6e as a colour-
colourless oil (57 mg, 67%) (Found: C, 75.47; H, 9.26. C H O
requires C, 75.90; H, 8.92%); νmax(CHCl )/cm 2997w, 2946s,
2
δ (200 MHz; CDCl ) 1.30–2.05 (10H, m, 5 × CH ), 1.79 (3H, s,
CH ), 2.12 [1H, dd, J
2
(
20
28
3
ϩ
less oil (64 mg, 65%) (Found: M , 316.2044. C H O requires
M, 316.2038); νmax(CHCl )/cm 3006m, 2947s, 2856m (CH),
1
CDCl ) 0.85–2.08 (10H, m, 5 × CH ), 1.14 (3H, d, J 6.7, Me),
2
and J2ax,3eq 2.3, 2 -H), 3.24 (1H, dd, J 5.1, J5ax,4ax 11.5,
5ax-H), 3.65–3.79 (1H, m, 8 -H), 4.04–4.19 (1H, m, 8 -H), 4.59
Ϫ1
20 28
3
3
Ϫ1
3
876m (CH), 1602w (C᎐C), 1454, 1357, 1290, 1115, 1090, 1004;
᎐
680m (C᎐C), 1454, 1356, 1098, 1009, 919; δ (200 MHz;
᎐
H
H
3
2
3
2
13.8, J1Јa,2ax 4.9, CH H C(CH )᎐CH ],
3
1Јa,1Јb
a
b
3
2
.13–2.31 (1H, m, CHMe), 3.11 (1H, ddd, J2ax,1Ј 8.4, J2ax,3ax11.0
.31 [1H, dd, J1Јb,1Јa 13.8, J 1Јb,2ax 7.6, CH H C(CH )᎐CH ], 3.26
a b 3 2
ax
5ax,4eq
1H, dd, J5ax,4ax 11.1, J5ax,4eq 4.9, 5 -H), 3.48–3.61 (1H, m,
ax
eq
ax
2ax-H), 3.63–3.76 (1H, m, 8 -H), 4.03–4.14 (1H, m, 8 -H), 4.60
eq
ax
(
1H, d, JA,B 12.1, OCH H Ar), 4.85 (1H, d, J 12.1, OCHA-
A B B,A
(
1H, d, JA,B 12.0, OCH H Ar), 4.85 (1H, d, J 12.0, OCHA-
A B B,A
H Ar), 4.95–5.08 (2H, m, CH᎐CH ), 5.70 (1H, ddd, J 17.1,
J2Ј,3a 10.0 and J2Ј,1Ј 8.1, 2Ј-H), 7.20–7.45 (5H, m, Ar-H); δ (50
MHz; CDCl ) 16.9 (CH , Me), 17.5, 22.0, 25.6, 26.9, 29.2 (CH ,
C-9, C-10, C-11, C-4 and C-3), 44.0 (CH, CHMe), 61.5 (CH2,
C-8), 72.7 (CH , OCH Ar), 75.1 (CH, C-2), 80.1 (CH, C-5),
B
2
2Ј,3Јb
H Ar), 4.74–4.80 (2H, m, ᎐CH ), 7.18–7.42 (5H, m, Ar-H);
δ (50 MHz; CDCl ) 17.5, 22.3, 25.5, 26.7, 30.9 (CH , C-9,
C-10, C-11, C-4 and C-3), 23.1 [CH , C(CH )᎐CH )], 44.2
B
2
C
C
3
2
3
3
2
3
3
2
[
CH , CH C(CH )᎐CH ], 61.4 (CH , C-8), 70.7 (CH, C-2),
2 2 3 2 2
2
2
7
2.7 (CH , OCH Ar), 79.9 (CH, C-5), 96.9 (quat., C-6), 112.4
2 2
1
00.0 (quat., C-6), 114.7 (CH , CH᎐CH ), 127.3, 127.7, 128.2
2 2
[
(
CH , C(CH )᎐CH ], 127.3, 127.7, 128.2 (CH, Ar-C), 139.2
2 3 2
ϩ
(
CH, Ar-C), 139.3 (quat., Ar-C), 140.8 (CH, CH᎐CH );
᎐
2
ϩ
quat., Ar-C), 142.9 [quat., C(CH )᎐CH ]; m/z 316 (M , 4%),
3 2
m/z (CI, CH ) 317 (MH , 22%), 302 (M Ϫ CH , 16), 261
4
3
2
1
61 (M Ϫ C H , 26), 225 (M Ϫ C H CH , 16) and 91 (C H ,
4 7 6 5 2 7 7
(
M Ϫ C H , 32), 209 (M Ϫ OBn, 100) and 91 (C H , 21).
4
7
7
7
00).
Modified procedure for 5f–g
(
2R*,5S*,6S*)-2-(1Ј,1Ј-Dimethylprop-2Ј-enyl)-5-benzyloxy-1,7-
The following modifications were made to the above general
allylation procedure: the potassium fluoride was omitted and
the reaction was quenched by the addition of a saturated solu-
tion of sodium hydrogen carbonate. The aqueous layer was
extracted with dichloromethane and the combined organic
layers were washed with water and dried over sodium sulfate.
dioxaspiro[5.5]undecane 5c
The title compound 5c was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (120 mg,
0
.375 mmol) and 2-methyl-4-(tributylstannyl)but-2-ene 6c as a
colourless oil (64 mg, 52%) (Found: C, 76.67; H, 9.29. C H O
3
2
1
30
Ϫ1
requires C, 76.31; H, 9.16%); νmax(CHCl )/cm 3085w (᎐CH),
3
᎐
2
1
1
948m, 2869s (CH), 1637w (C᎐C), 1495, 1454, 1356, 1113,
(2R*,5S*,6S*,1ЈR*)- and (2R*,5S*,6S*,1ЈS*)-2-(1Ј-tert-Butyl-
dimethylsilyloxyprop-2Ј-enyl)-5-benzyloxy-1,7-dioxaspiro[5.5]-
undecane 5f
᎐
082, 1012; δ (200 MHz; CDCl ) 1.20–2.05 (10H, m, 5 × CH ),
H
3
2
.05 (3H, s, Me), 1.07 (3H, s, Me), 3.10 (1H, dd, J2ax,3eq 1.9,
J2ax,3ax 11.0, 2 -H), 3.19 (1H, dd, J 5.1, 7.0, 5 -H), 3.68–3.76
The title compound 5f was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (160 mg,
0.5 mmol) and the stannane 6f as a colourless oil (62 mg, 28%)
ax
ax
(
1H, m, 8 -H), 4.05–4.19 (1H, m, 8 -H), 4.58 (1H, d, J 12.0,
eq ax A,B
OCH H Ar), 4.86 (1H, d, J
12.0, OCH H Ar), 4.95
A
B
B,A
A
B
ϩ
(
1H, dd, J3Јa,2Ј 5.9, J3Јa,3Јb 1.4, CH᎐CH H ), 5.02 (1H, br s,
(Found: M , 432.2701. C H O Si requires M, 432.2695);
a
b
25 40
4
Ϫ1
CH᎐CH H ), 5.88–6.03 (1H, m, CH᎐CH ), 7.19–7.40 (5H, m,
νmax(CHCl )/cm 3006w, 2954s, 2857m (CH), 1602w (C᎐C),
᎐
a
b
2
3
Ar-H); δ (50 MHz; CDCl ) 17.4, 21.9, 25.3, 25.6, 27.0 (CH ,
1462, 1360, 1257, 1206, 1094, 1006, 837; δ (200 MHz; CDCl )
C
3
2
H
3
t
C-9, C-10, C-11, C-4 and C-3), 23.3, 23.7 (CH , 2 × Me), 40.4
0.11 (6H, m, SiMe ), 0.9 (9H, m, Bu ), 1.18–2.07 (10H, m,
3
2
(
quat., CMe ), 61.4 (CH , C-8), 72.7 (CH , OCH Ar), 78.3
5 × CH ), 3.15–3.40 (2H, m, 5 -H and 2 -H), 3.62–3.80 (1H,
2
2
2
2
2
ax
ax
(
CH, C-2), 80.3 (CH, C-5), 100.0 (quat., C-6), 111.7 (CH2,
m, 8 -H), 4.05–4.22 (2H, m, 8 -H and CHOSi), 4.60 (1H, d,
e
q
a
x
CH᎐CH ), 127.2, 127.6, 128.2 (CH, Ar-C), 139.3 (quat., Ar-C),
JA,B 12.0, OCH H Ar), 4.83 (1H, d, J
12.0, OCH H Ar),
B,A A B
᎐
2
A
B
ϩ
1
45.4 (CH, CH᎐CH ); m/z (CI, CH ) 331 (MH , 37%), 316
5.05–5.25 (2H, m, CH᎐CH ), 5.72–5.91 (1H, m, CH᎐CH ),
᎐
2
4
᎐
2
2
(
M Ϫ CH , 25), 261 (M Ϫ C H , 27), 223 (M Ϫ OBn, 100) and
7.15–7.36 (5H, m, Ar-H); δ (50 MHz; CDCl ) Ϫ4.7, Ϫ4.4
C 3
3
5
4
9
1 (C H , 20).
(CH , Me Si), 17.1, 22.2, 25.5, 26.7, 27.4 (CH , C-9, C-10, C-11,
7
7
3
2
2
J. Chem. Soc., Perkin Trans. 1, 1998
681

View Article Online
C-4 and C-3), 18.2 (quat., CMe ), 25.8 (CH , CMe ), 61.3 (CH ,
fied by flash chromatography using hexane–ethyl acetate (9:1
3
3
3
2
C-8), 72.7 (CH , OCH Ar), 75.4 (CH, C-2), 76.4 (CH, CHOSi),
containing 1% of triethylamine) as eluent to afford:
2
2
8
1
0.2 (CH, C-5), 100.1 (quat., C-6), 116.0 (CH , CH᎐CH ),
(i) The less polar product identified as the (6R*,8S*,14S*)-
diastereomer 12a as a colourless oil (28.0 mg, 40%) (Found:
2
2
27.3, 127.6, 128.2 (CH, Ar-C), 137.3 (CH, CH᎐CH ), 139.3
᎐
2
ϩ
ϩ
(
quat., Ar-C); m/z 432 (M , 6%), 341 (M Ϫ C H CH , 70), 241
M , 344.1992. C H O requires M, 344.1987); ν (CHCl )/
6
5
2
21 28
4
max
3
Ϫ1
(
20), 91 (C H CH , 100) and 73 (45).
cm 3013m, 2949s, 2889m (CH), 1657w (C᎐C), 1361, 1260,
6
5
2
1
095, 1050, 980, 911; δ (200 MHz; CDCl ) 1.26–2.44 (13H, m,
H
3
(
2
2R*,5S*,6S*)-2-[2Ј-(2Љ-tert-Butyldiphenylsilyloxyethyl)prop-
Ј-enyl]-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 5g
6 × CH and 5 -H), 2.65 (1H, d, J
13.7, 5 -H), 3.24 (1H,
2
eq
5ax,5eq
ax
dd, J14ax,15ax 6.8, J14ax,15eq 4.3, 14 -H), 3.58–3.79 (2H, m, 2 -H
a
x
e
q
The title compound 5g was prepared from (2R*,5S*,6S*)-2-
acetoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane 1 (50 mg,
and 10 -H), 3.99–4.15 (2H, m, 2 -H and 10 -H), 4.63 (2H, s,
eq ax ax
OCH Ar), 4.83 (1H, br s, ᎐CH H ), 4.77 (1H, br s, ᎐CH H ),
2
A
B
A
B
0
5
.156 mmol) and the stannane 6g as a colourless oil (53 mg,
7.19–7.39 (5H, m, Ar-H); δ (50 MHz; CDCl ) 19.0, 21.0, 25.4,
C
3
ϩ
8%) (Found: M , 584.3328. C H O Si requires M, 584.3322);
29.9, 32.6, 34.0 (CH , C-3, C-11, C-12, C-13, C-15 and C-16),
37
48
4
2
Ϫ1
νmax(CHCl )/cm 3028w (᎐CH), 2946s, 2858m (CH), 1602w
44.7 (CH , C-5), 61.7 (CH , C-10), 62.0 (CH , C-2), 71.8 (CH ,
3
2
2
2
2
(
C᎐C), 1455, 1428, 1360, 1226, 1111, 1008, 899, 822; δ (200
OCH Ar), 78.4 (CH, C-14), 98.4, 99.7 (quat., C-6 and C-8),
᎐
H
2
t
MHz; CDCl ) 1.05 (9H, s, Bu ), 1.25–2.28 (12H, m, 6 × CH ),
110.3 (CH , ᎐CH ), 127.4, 127.8, 128.2 (CH, Ar-C), 138.8
3
2
2
2
2
.36 (2H, t, J 6.9, CH CH OSi), 3.25 (1H, dd, J
11.1 and
(quat., Ar-C), 142.1 (quat., C᎐CH ).
2
2
5ax,4ax
᎐
2
J5ax,4eq 4.9, 5 -H), 3.39–3.53 (1H, m, 2 -H), 3.67–3.75 (1H, m,
(ii) The more polar product identified as the (6S*,8S*,14S*)-
diastereomer 12b as a colourless oil (21.0 mg, 30%) (Found:
ax
ax
8eq-H), 3.78 (2H, t, J 6.9, CH OSi), 3.99–4.10 (1H, m, 8 -H),
2
ax
ϩ
4
.60 (1H, d, JA,B 12.0, OCH H Ar), 4.85 (1H, d, J
12.0,
M , 344.1991. C H O requires M, 344.1987); ν (CHCl )/
A
B
B,A
21 28
4
max
3
Ϫ1
OCH H Ar), 4.79–4.86 (2H, m, ᎐CH ), 7.28–7.44 (10H, m,
cm 3015m, 2952s, 2893m (CH), 1653w (C᎐C), 1365, 1264,
1100, 1039, 983, 908; δ (200 MHz; CDCl ) 1.26–2.36 (13H, m,
A
B
2
Ar-H) and 7.66–7.70 (5H, m, Ar-H); δ (50 MHz; CDCl ) 17.5,
C
3
H
3
2
1
2.3, 25.5, 26.7, 30.9 (CH , C-9, C-10, C-11, C-4 and C-3),
6 × CH and 5 -H), 2.41 (1H, d, J
dd, J14,15eq 3.4, J14,15ax 4.7, 14 pseudoaxial-H), 3.55–3.78 (2H, m,
13.4, 5 -H), 3.46 (1H,
2
2
eq
5ax,5eq
ax
9.2 (quat., CMe ), 26.8 (CH , CMe ), 39.3, 42.8 (CH , C-1Ј
3
3
3
2
and C-1Љ), 61.4 (CH , C-8), 62.9 (CH , CH OSi), 70.8 (CH,
2 -H and 10 -H), 3.97–4.11 (2H, m, 2 -H and 10 -H), 4.50
2
2
2
eq
eq
ax
ax
C-2), 72.7 (CH , OCH Ar), 79.9 (CH, C-5), 99.9 (quat., C-6),
(1H, d, JA,B 11.9, OCH H Ar), 4.63 (1H, d, J 11.9, OCHA-
2
2
A B B,A
1
13.4 (CH , ᎐CH ), 127.3, 127.6, 127.7, 128.2, 129.6, 135.6
H Ar), 4.78 (1H, br s, ᎐CH H ), 4.74 (1H, br s, ᎐CH H ),
B A B A B
2
2
(
CH, Ar-C), 133.9, 139.2 (quat., Ar-C), 143.6 (quat., C᎐CH );
7.22–7.39 (5H, m, Ar-H); δ (50 MHz; CDCl ) 18.3, 18.6, 25.5,
᎐
2
C
3
ϩ
m/z (CI, CH ) 585 (MH , 9%), 477 (M Ϫ OBn, 22), 399
28.2, 32.4, 34.1 (CH , C-3, C-11, C-12, C-13, C-15 and C-16),
4
2
(
(
M Ϫ OBn Ϫ C H , 20), 329 (M Ϫ C H OSi Ϫ OBn, 34), 261
46.4 (CH , C-5), 61.7 (CH , C-10), 62.6 (CH , C-2), 71.1 (CH ,
6
5
16 19
2
2
2
2
M Ϫ C H OSi, 57), 91 (C H CH , 24) and 153 (C H O , 100).
OCH Ar), 76.1 (CH, C-14), 97.9, 98.1 (quat., C-6 and C-8),
21
27
6
5
2
9
13
2
2
1
09.6 (CH , ᎐CH ), 127.4, 127.6, 128.3 (CH, Ar-C), 138.8
2 2
(
2R*,5S*,6S*)-2-[2Ј-(2Љ-Hydroxyethyl)prop-2Ј-enyl]-5-benzyl-
(quat., Ar-C), 142.1 (quat., C᎐CH ).
᎐
2
oxy-1,7-dioxaspiro[5.5]undecane 5h
Tetra-n-butylammonium fluoride (0.31 cm of a 1.0  solution
in tetrahydrofuran, 0.31 mmol) was added to a solution of 5g
3
(2S*,5S*,6S*)-2-(3Ј-Hydroxypropyl)-5-benzyloxy-1,7-dioxa-
spiro[5.5]undecane 7
To a solution of 5a (169 mg, 0.56 mmol) in dry THF (20 cm ) at
3
3
(
163 mg, 0.28 mmol) in dry tetrahydrofuran (10 cm ) at room
temperature under argon. After stirring for 30 min, the solvent
was evaporated and the oily residue purified by flash chrom-
atography, using hexane–ethyl acetate (7:3) as eluent to afford
the title compound 5h (87 mg, 90%) as a colourless oil (Found:
0 ЊC and under Ar was added dropwise a 1  solution of BH –
THF complex (3.08 cm , 3.08 mmol) and stirred at room tem-
3
3
perature for 5 h. The mixture was then cooled to 0 ЊC and
treated with a 3  aqueous solution of sodium hydroxide (18
ϩ
3
M , 346.2150. C H O requires M, 346.2144); ν (CHCl )/
cm ). Oxidation was then carried out by slow dropwise addition
2
1
30
4
max
3
Ϫ1
3
cm 3450 (br s, OH), 3032w (᎐CH), 2946s, 2881s (CH), 1642w
C᎐C), 1454, 1357, 1262, 1080, 1047, 1009, 908; δ (200 MHz;
of 30% H O (18 cm ) with the temperature being maintained
2
2
(
below 40 ЊC. After stirring for an additional 0.5 h, the reaction
᎐
H
CDCl ) 1.27–2.28 (13H, m, 6 × CH and OH), 2.35 (2H, t,
mixture was poured into water and extracted with dichloro-
methane (3 × 30 cm ). The combined extracts were washed with
3
2
3
J 6.3, CH CH OH), 3.23 (1H, dd, J
11.1 and J5ax,4eq 4.9,
2
2
5ax,4ax
5ax-H), 3.48–3.61 (1H, m, 2 -H), 3.70 (2H, t, J 6.3, CH OH),
brine, dried over sodium sulfate and concentrated under
reduced pressure to give a colourless oil which was purified by
flash chromatography using hexane–ethyl acetate (1:1) as elu-
ent to afford the title compound 7 (120 mg, 68%) as a colourless
ax
2
3
.67–3.73 (1H, m, 8 -H), 3.97–4.07 (1H, m, 8 -H), 4.57 (1H, d,
eq
ax
JA,B 12.0, OCH H Ar), 4.82 (1H, d, J
12.0, OCH H Ar),
A
B
B,A
A
B
4
.90 (1H, br s, ᎐CH H ), 4.94 (1H, br s, ᎐CH H ), 7.16–7.39
᎐
A B A B
ϩ
(
(
5H, m, Ar-H); δ (50 MHz; CDCl ) 17.4, 22.2, 25.4, 26.6, 30.8
oil (Found: M , 320.1992. C H O requires M, 320.1987);
C
3
19 28
4
Ϫ1
CH , C-9, C-10, C-11, C-4 and C-3), 39.6, 41.9 (CH , C-1Ј
νmax(CHCl )/cm 3206 (br s, OH), 3024m (᎐CH), 2947s, 2876s
2
2
3
and C-1Љ), 60.4 (CH , C-8), 61.5 (CH , CH OH), 71.2 (CH,
(CH), 1454, 1357, 1262, 1090, 1009, 908; δ (200 MHz; CDCl )
2
2
2
H
3
C-2), 72.7 (CH , OCH Ar), 79.8 (CH, C-5), 100.0 (quat., C-6),
1.20–2.09 (14H, m, 7 × CH ), 2.21 (1H, br s, OH), 3.25 (1H,
2
2
2
1
14.0 (CH , ᎐CH ), 127.2, 127.6, 128.1 (CH, Ar-C), 139.1
dd, J5ax,4ax 11.0, J5ax,4eq 4.9, 5 -H), 3.32–3.48 (1H, m, 2 -H),
2
2
ax
ax
ϩ
(
quat., Ar-C), 143.4 (quat., C᎐CH ); m/z 346 (M , 0.15%), 261
3.64 (2H, t, J 5.9, CH OH), 3.70–3.79 (1H, m, 8 -H), 3.97–4.14
᎐
2
2
e
q
(
M Ϫ C H O, 7), 155 (M Ϫ C H O , 35), 96 (100), 107 (60) and
(1H, m, 8 -H), 4.60 (1H, d, J 12.0, OCH H Ar), 4.84 (1H,
ax A,B A B
5
9
9
13
2
5
5 (82).
d, JB,A 12.0, OCH H Ar), 7.19–7.39 (5H, m, Ar-H); δ (50 MHz;
A
B
C
CDCl ) 17.4, 22.0, 25.3, 26.7, 29.2, 31.0, 32.1 (CH , C-9, C-10,
3
2
(
6R*,8S*,14S*)- and (6S*,8S*,14S*)-14-Benzyloxy-4-methyl-
C-11, C-4, C-3, C-1Ј, C-2Ј), 61.4 (CH , C-8), 62.6 (CH ,
CH OH), 71.6 (CH, C-2), 72.6 (CH , OCH Ar), 79.9 (CH,
2 2 2
2
2
idene-1,7,9-trioxadispiro[5.1.5.3]hexadecane 12a and 12b
A solution of the alcohol 5h (70 mg, 0.20 mmol), iodine (102
mg, 0.40 mmol), and iodobenzene diacetate (129 mg, 0.40
C-5), 99.9 (quat., C-6), 127.2, 127.6, 128.1 (CH, Ar-C), 139.0
ϩ
(quat., Ar-C); m/z (CI, CH ) 321 (MH , 17%), 303 (M Ϫ OH,
4
3
mmol) in cyclohexane (20 cm ) was purged with Ar and irradi-
26), 214 (M Ϫ OBn, 81) and 195 (M Ϫ H O Ϫ OBn, 100).
2
ated with a 500 W tungsten filament lamp. After 4 h, during
which time the temperature was maintained at about 23 ЊC, the
(2S*,5S*,6S*)-3-(5-Benzyloxy-1,7-dioxaspiro[5.5]undec-2-yl)-
propyl p-nitrobenzoate 8
3
solution was diluted with diethyl ether (25 cm ), washed with
3
3
1
(
0% aqueous sodium thiosulfate (20 cm ), water (20 cm ), brine
To a solution of the alcohol 7 (58 mg, 0.18 mmol) in dichloro-
3
3
3
20 cm ) and dried over potassium carbonate. The solvent was
methane (9 cm ) was added triethylamine (0.05 cm , 0.36 mmol)
followed by 4-nitrobenzoyl chloride (40 mg, 0.216 mmol) and
evaporated under reduced pressure and the resultant oil puri-
6
82
J. Chem. Soc., Perkin Trans. 1, 1998

View Article Online
3
4
-dimethylaminopyridine (3 mg). The mixture was stirred at
cm ) was added a solution of dimethyldioxirane in acetone (50
3 Ϫ3
room temperature for 30 min. Saturated sodium hydrogen
cm , 5.5 mmol as a 0.1 mmol cm solution in acetone) and the
reaction mixture allowed to stir for 1 h at room temperature.
Removal of solvent under reduced pressure gave an oil which
was dissolved in dichloromethane (50 ml) and dried over
sodium sulfate. To the filtered solution was added dry triethyl-
amine (1.17 g, 11.5 mmol), acetic anhydride (845 mg, 8.28
mmol) and 4-(dimethylamino)pyridine (3 mg) and the reaction
mixture was stirred gently at room temperature for 3 h. The
3
carbonate solution (5 cm ) was added and the mixture extracted
3
3
with dichloromethane (3 × 20 cm ), washed with brine (10 cm )
and dried over potassium carbonate. The solvent was then
evaporated to give a yellow oil which was purified by flash
chromatography using hexane–ethyl acetate (4:1) to afford the
title compound 8 (75.6 mg, 89%) as colourless needles, mp 75–
7
7
3
6 ЊC (from MeOH); δ (200 MHz; CDCl ) 1.30–2.20 (14H, m,
H
3
3
× CH ), 3.26 (1H, dd, J
11.2, J5ax,4eq 5.0, 5 -H), 3.39–
reaction was quenched with water (30 cm ), extracted with
2
5ax,4ax
ax
3
.53 (1H, m, 2 -H), 3.70–3.81 (1H, m, 8 -H), 4.07–4.20
dichloromethane (2 × 50 cm ) and dried over sodium sulfate.
ax
eq
(
1H, m, 8 -H), 4.38–4.46 (2H, m, CH OC᎐O), 4.60 (1H, d,
Removal of the solvent under reduced pressure gave a yellow oil
which was purified by flash chromatography using hexane–ethyl
acetate (4:1) as eluent to afford the title compound 10 (810 mg,
56%) as a colourless solid, mp 91–92 ЊC (Found: C, 63.42; H,
ax
2
JA,B 12.0, OCH H Ar), 4.85 (1H, d, J
7
MHz; CDCl ) 17.6, 22.1, 25.4, 25.6, 26.7, 31.2, 32.5 (CH ,
C-9, C-10, C-11, C-4, C-3, C-3Ј, C-2Ј), 60.4 (CH , C-8), 66.0
12.0, OCH H Ar),
A
B
B,A
A B
.28–7.40 (5H, m, Ar-H), 8.20–8.45 (4H, m, Ar-H); δ (50
C
3
2
Ϫ1
7.00. C H O requires C, 63.46; H, 6.93%); ν (CHCl )/cm
2
20 26
7
max
3
(
(
1
(
CH , CH OC᎐O), 71.4 (CH, C-2), 72.7 (CH , OCH Ar), 79.9
CH, C-5), 100.0 (quat., C-6), 123.5, 127.3, 127.7, 128.2,
30.7 (CH, Ar-C), 135.7, 139.1, 150.5 (quat., Ar-C), 164.7
3042w (᎐CH), 2948w (CH), 1740s (C᎐O, acetate), 1228s (C᎐O),
1454, 1370, 1217, 1093, 1053, 983, 796; δ (200 MHz; CDCl )
2
2
2
2
H
3
1.16–1.32 (1H, ddd, J11ax,11eq 13.3, J11ax,10ax 13.3, J11ax,10eq 4.5,
11 -H), 1.50–1.98 (6H, m, 9-CH , 10-CH , 11 -H and 4 -H),
quat., C᎐O).
᎐
ax
2
2
eq
eq
2
.40 (1H, m, 4 -H), 2.11 and 2.18 (2 × 3H, 2s, 2 × Ac), 3.34
ax
(
5S*,7S*,13S*)- and (5R*,7S*,13S*)-13-Benzyloxy-1,6,8-tri-
(1H, t, J 2.8, 5 -H), 3.70–3.80 (1H, m, 8 -H), 4.1–4.2 (1H, m,
8ax-H), 4.55 (1H, d, JA,B 11.9, OCH H Ar), 4.79 (1H, d, J
A B B,A
e
q
e
q
oxadispiro[4.1.5.3]pentadecane 11a and 11b
A solution of the alcohol 7 (94 mg, 0.30 mmol), iodine (153 mg,
11.9, OCH H Ar), 5.18 (1H, ddd, J3ax,4ax11.6, J3ax,2ax 8.5 and
A B
0
.60 mmol), and iodobenzene diacetate (192 mg, 0.60 mmol) in
J3ax,4eq 5.2, 3 -H), 6.0 (1H, d, J
8.5, 2 -H), 7.38–7.41 (5H,
2ax,3ax ax
ax
3
cyclohexane (25 cm ) was purged with Ar and irradiated with a
00 W tungsten filament lamp. After 1 h, during which time the
m, Ar-H); δ (50 MHz; CDCl ) 18.4, 25.2, 27.6, 31.0 (CH , C-9,
C
3
2
5
C-10, C-11 and C-4), 21.4 (CH , 2 × Ac), 61.9 (CH , C-8), 67.5
3 2
temperature was maintained at about 23 ЊC, the solution was
(CH, C-3), 71.1 (CH , OCH Ar), 76.9 (CH, C-5), 89.7 (CH,
2 2
3
diluted with diethyl ether (75 cm ), washed with 10% aqueous
C-2), 99.7 (quat., C-6), 127.5, 128.0, 128.4, 128.6 (CH, Ar-C),
138.0 (quat., Ar-C), 170.2 (quat., 2 × C᎐O); m/z (CI, CH ) 379
3
3
3
sodium thiosulfate (30 cm ), water (30 cm ), brine (30 cm ) and
dried over potassium carbonate. The solvent was evaporated
under reduced pressure and the resultant oil purified by flash
chromatography using hexane–ethyl acetate (4:1 containing 1%
of triethylamine) as eluent to afford:
᎐
4
ϩ
(MH , 0%), 319 (MH Ϫ Ac, 73), 259 (MH Ϫ 2Ac, 45) and 211
(MH Ϫ OAc Ϫ OBn, 100).
Crystal data and structure refinement for 1 and 8
(
i) The less polar product identified as the (5S*,7S*,13S*)-
1: C H O , M = 320.38, orthorhombic, space group Pbca
18
24
5
diastereomer 11a (25.2 mg, 26.4%) as a colourless oil (Found:
(#61), a = 26.882(4), b = 14.808(6), c = 8.632(5) Å, V = 3436(1)
3 Ϫ3
ϩ
M , 318.1836. C H O requires M, 318.1831); ν (CHCl )/
Å , Z = 8, D = 1.239 g cm , F(000) = 1376.00, µ(Cu-Kα) = 7.36
c
Ϫ1
1
9
26
4
max
3
Ϫ1
cm 3004m, 2947s, 2881m (CH), 1585, 1453, 1359, 1148, 1097,
cm , crystal size 0.55 × 0.05 × 0.03 mm, T
0.87, 0.99,
min,max
1
7
3
046, 979, 947; δ (200 MHz; CDCl ) 1.49–2.31 (14H, m,
N = 2945, N = 1099 [I > 3.0σ(I)], hkl 0 30, 0 16, 0 9, 2θ
=
H
3
o
max
× CH ), 3.25 (1H, dd, J
7.5, J13ax,14eq 4.4, 13 -H), 3.62–
120.1Њ, R* = 0.041, R * = 0.041, residual extrema Ϫ0.19 0.15 e
2
13ax,14ax
ax
w
Ϫ3
.75 (1H, m, 9 -H), 3.82–3.95 (2H, m, 2-CH ), 4.00–4.14 (1H,
Å .
eq
2
m, 9 -H), 4.61 (1H, d, J 12.0, OCH H Ar), 4.70 (1H, d, J
8: C H NO , M = 469.53, monoclinic, space group P2 /a
ax
A,B
A
B
B,A
26 31
7
1
1
2.0, OCH H Ar), 7.24–7.42 (5H, m, Ar-H); δ (50 MHz;
(#14), a = 11.352(4), b = 11.775(2), c = 18.602(2) Å, β =
A
B
C
3
Ϫ3
CDCl ) 18.5, 23.0, 24.4, 25.6, 29.4, 31.5, 37.8 (CH , C-3, C-4,
C-10, C-11, C-12, C-14, C-15), 61.6 (CH , C-9), 68.1 (CH ,
100.65(2)Њ, V = 2443.7(8) Å . Z = 4, D = 1.276
g
cm ,
3
2
c
Ϫ1
F(000) = 1000.00, µ(Cu-Kα) = 7.64 cm , crystal size 0.30 ×
2
2
C-2), 71.9 (CH , OCH Ar), 78.7 (CH, C-13), 100.0 (quat., C-7),
0.10 × 0.08 mm, Tmin,max 0.87, 0.99, N = 4623, Nind = 4286
2
2
1
07.2 (quat., C-5), 127.3, 127.6, 128.2 (CH, Ar-C), 138.9 (quat.,
(Rmerge = 0.024), N = 1386 [I > 3.0σ(I)], hkl 0 13, 0 13, Ϫ21 21,
o
ϩ
Ar-C); m/z (CI, CH ) 319 (MH , 0.7%), 317 (M Ϫ H, 16),
3
2θmax = 130.2Њ, Ϫ3R* = 0.054, R * = 0.051, residual extrema
4
w
01 (M Ϫ OH, 100), 211 (M Ϫ OBn, 87) and 193 (M Ϫ
Ϫ0.20 0.17 e Å .
OBn Ϫ H O, 37).
* R = Σ(|F | Ϫ |F |)/Σ|F |
2
o
c
o
2
2 ¹
2
R = (Σw(|F | Ϫ |F |) /Σw|F | ) ; w = 1/σ (F )
�
²
(
ii) The more polar product identified as the (5R*,7S*,13S*)-
w
o
c
o
o
diastereomer 11b (37.4 mg, 39%) as a colourless oil (Found:
Atomic coordinates, thermal parameters and bond lengths have
been deposited at the Cambridge Crystallographic Data Centre
(CCDC).‡
ϩ
M , 318.1837. C H O requires M, 318.1831); ν (CHCl )/
1
9
26
4
max
3
Ϫ1
cm 3004m, 2946s, 2885m (CH), 1453, 1442, 1379, 1216, 1181,
1
3
3
069, 982; δ (200 MHz; CDCl ) 1.17–2.21 (14H, m, 7 × CH ),
A colourless acicular crystal of 1 was attached to a thin glass
fibre and mounted on a Rigaku AFC7R diffractometer employ-
ing graphite monochromated Cu-Kα radiation (λ = 1.541 78 Å)
from a rotating anode generator. A colourless blade like crystal
of 8 cut from a cluster was similarly mounted on the AFC7R
diffractometer. Diffraction data were collected at a temperature
of 21 ± 1 ЊC using ω Ϫ 2θ scans to a maximum 2θ value of
120.1Њ for 1 and 130.2Њ for 8. In both cases, the intensities of
three representative reflections measured every 150 reflections,
did not change significantly during the data collection. An
H
3
2
.26 (1H, dd, J 3.3 and 1.5, 13 -H), 3.56–3.66 (1H, m, 9 -H),
eq
eq
.80–3.97 (2H, m, 2-CH ), 4.04–4.13 (1H, m, 9 -H), 4.44 (1H,
2
ax
d, JA,B 12.0, OCH H Ar), 4.65 (1H, d, J 12.0, OCH H Ar),
A
B
B,A
A
B
7
.20–7.42 (5H, m, Ar-H); δ (50 MHz; CDCl ) 18.4, 19.0, 24.4,
C
3
2
5.6, 27.9, 33.0, 39.8 (CH , C-3, C-4, C-10, C-11, C-12, C-14,
2
C-15), 61.0 (CH , C-9), 69.3 (CH , C-2), 70.9 (CH , OCH Ar),
2
2
2
2
7
1
8.2 (CH, C-13), 97.0 (quat., C-7), 106.2 (quat., C-5), 127.5,
27.8, 128.2 (CH, Ar-C), 138.9 (quat., Ar-C); m/z (CI, CH ) 319
4
ϩ
(
(
MH , 0.6%), 317 (M Ϫ H, 19), 301 (M Ϫ OH, 93), 211
M Ϫ OBn, 100) and 193 (M Ϫ OBn Ϫ H O, 46).
2
‡
For details of the deposition scheme, see ‘Instructions for Authors’,
(
2R*,3S*,5S*,6S*)-5-Benzyloxy-2,3-diacetoxy-1,7-dioxaspiro-
5.5]undecane 10
J. Chem. Soc., Perkin Trans. 1, available via the RSC Web page (http://
www.rsc.org/authors). Any request to the CCDC for this material
should quote the full literature citation and the reference number 207/
177.
[
To a solution of (5S*,6S*)-5-benzyloxy-1,7-dioxaspiro[5.5]-
undec-2-ene 2 (1.00 g, 3.85 mmol) in dry dichloromethane (20
J. Chem. Soc., Perkin Trans. 1, 1998
683

View Article Online
empirical absorption correction based on azimuthal scans of
three reflections was applied and the data were also corrected
for Lorentz and polarization effects.
Chemical Society, Washington DC, 1993; (c) P. P. Graczyk and
M. Mikolajczyk, Top. Stereochem., 1994, 21, 159; (d) E. Juaristi and
G. Cuevas, Tetrahedron, 1992, 48, 5019.
M. A. Brimble and G. M. Williams, J. Org. Chem., 1992, 57, 5818.
(a) R. L. Dorta, A. Martin, E. Suarez and T. Prange, Tetrahedron:
Asymmetry, 1996, 7, 1907; (b) A. Martin, J. A. Salazar and
E. Suarez, J. Org. Chem., 1996, 61, 3999.
8
9
16
All calculations were undertaken with the TEXSAN crys-
tallographic software package. Neutral atom scattering factors
17
were taken from Cromer and Waber. Anomalous dispersion
18
effects were included in Fcalc and the values for ∆f Ј and ∆f Љ
10 M. A. Brimble and C. J. Rush, J. Chem. Soc., Perkin Trans. 1, 1994,
497.
11 (a) M. A. Brimble and A. D. Johnston, J. Org. Chem., in the press;
19
were those of Creagh and McAuley. The values for the mass
2
0
attenuation coefficients were those of Creagh and Hubbell.
(
b) M. A. Brimble, A. D. Johnston and R. Furneaux, Tetrahedron
21
The structures were solved by direct methods and expanded
Lett., 1997, 38, 3591.
2 Y. Naruta, Y. Nishigaichi and K. Maruyama, Chem. Lett., 1986,
1857.
13 S. Weigand and R. Bruckener, Synthesis, 1995, 475.
14 A. Barbero, P. Cuadrado, I. Fleming, A. M. Gonzalez and F. J.
Pulido, J. Chem. Soc., Perkin Trans. 1, 1992, 327.
22
using Fourier techniques. Non-hydrogen atoms were modelled
with anisotropic thermal parameters and hydrogen atoms were
included in the model at calculated positions with group
thermal parameters. ORTEP projections of the molecule are
provided in Figs. 1 and 2.
1
23
1
5 G. E. Keck, D. E. Abbott and M. R. Wiley, Tetrahedron Lett., 1987,
8, 139.
2
1
6 TEXSAN: Crystal Structure Analysis Package, Molecular Structure
Corporation (1985 & 1992).
Acknowledgements
This work was supported by an Australian Research Council
Grant. We are indebted to Associate Professor Damon Ridley
for his invaluable help with CAS on-line searching.
17 D. T. Cromer and J. T. Waber, in International Tables for X-ray
Crystallography, The Kynoch Press, Birmingham, England, 1974,
vol. IV, Table 2.2 A.
1
1
8 J. A. Ibers and W. C. Hamilton, Acta Crystallogr., 1964, 17, 781.
9 D. C. Creagh and W. J. McAuley, in International Tables for
Crystallography, ed. A. J. C. Wilson, Kluwer Academic Publishers,
Boston, 1992, vol. C, Table 4.2.6.8, pp. 219–222.
References
1
2
3
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American Chemical Society Symposium Series, 539, American
Paper 7/07607J
Received 21st October 1997
Accepted 26th November 1997
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84
J. Chem. Soc., Perkin Trans. 1, 1998