Conversion of Epoxides to 1,3-Dioxolanes Catalyzed by Tin(II) Chloride

Article abstract of DOI:10.1021/jo035112y

Anhydrous tin(II) chloride is an efficient catalyst for the reaction of epoxides with acetone to prepare 2,2-dimethyl-1,3-dioxolanes (acetonides) in good to excellent yields. Mono-, di-, and trisubstituted epoxides participate equally well in this diastereospecific reaction. The use of single enantiomer epoxides under the reported conditions results in significant erosion of optical activity.

Full text of DOI:10.1021/jo035112y

TABLE 1. Con ver sion of Mon osu bstitu ted Ep oxid es to
Aceton id es
Con ver sion of Ep oxid es to 1,3-Dioxola n es
Ca ta lyzed by Tin (II) Ch lor id e
J ames R. Vyvyan,*,† J ennifer A. Meyer, and
Korin D. Meyer
Department of Chemistry, Western Washington University,
Bellingham, Washington 98225-9150
mol %
SnCl2
3
R
4
% yielda
vyvyan@chem.wwu.edu
Received J uly 29, 2003
3a
3a
3b
3c
3d
3e
3f
3g
3h
3i
CH3(CH2)5
CH3(CH2)5
CH3(CH2)9
CH2dCHCH2OCH2
C6H5
BnOCH2
CH2dCHCH2CH2
CH2dCH
10
1
1
1
1
1
1
2
5
1
1
1
1
4a
4a
4b
4c
4d
4e
4f
4g
4h
4i
95
97
92
95
90
80
71
48
63
77
67
73
64
Abstr a ct: Anhydrous tin(II) chloride is an efficient catalyst
for the reaction of epoxides with acetone to prepare 2,2-
dimethyl-1,3-dioxolanes (acetonides) in good to excellent
yields. Mono-, di-, and trisubstituted epoxides participate
equally well in this diastereospecific reaction. The use of
single enantiomer epoxides under the reported conditions
results in significant erosion of optical activity.
c-C6H11
MOMOCH2(CH2)8
BnOCH2(CH2)8
TBSOCH2(CH2)8
PMBOCH2(CH2)8
3j
3k
3l
4j
4k
4l
a
Isolated yield of purified material.
The 2,2-dimethyl-1,3-dioxolane (acetonide) group is
perhaps the most widely used protecting group for vicinal
diols. Preparation of acetonides usually involves reaction
of the diol with acetone, 2,2-dimethoxypropane, or 2-meth-
oxypropene under acidic conditions.1 The diols themselves
are typically prepared via osmium-catalyzed dihydroxy-
lation of the corresponding alkene or hydration of the
epoxide precursor, respectively.2
or protecting groups. Herein we report the direct conver-
sion of epoxides to 2,2-dimethyl-1,3-dioxolanes (aceto-
nides) catalyzed by the mild Lewis acid SnCl2.
During the course of our studies directed toward the
synthesis of benzoxocane-containing natural products, we
observed that acetonide 2 was formed (along with other
products) when acetone was added to a suspension of
epoxide 1 and anhydrous SnCl2 in chloroform in an
attempt to improve the solubility of the reaction inter-
mediates (eq 1).17 We then investigated the action of
SnCl2 on a variety of structurally simplified epoxides in
acetone solvent.
The direct conversion of epoxides to the corresponding
acetonides has been previously reported using a variety
of Lewis acid catalysts including BF3‚OEt2,3 SnCl4,4 and
5
anhydrous CuSO4 with varying degrees of success
pertaining to yield and selectivity. Other catalysts that
have been used for this transformation include TiCl4,6
TiCl3(OTf) and TiO(TFA)2,7 K5CoW12O40‚3H2O,8 [C5Me5-
Ir(NaMe)3],9 RuCl3,10 K10-montmorillonite,11 bismuth(III)
salts,12 2,4,4,6-tetrabromo-2,5-cyclohexadienone,13 tin(IV)
tetraphenylporphyrin perchlorate,14 CH3ReO3,15 and vari-
ous zeolites.16 Many of these catalysts are rather strong
Lewis acids and are incompatible with other functional
Reaction of 1,2-epoxyoctane (3a ) with 10 mol % anhy-
drous SnCl2 in acetone at reflux for 1 h provided di-
oxolane 4a in 95% yield after extractive workup and
purification by MPLC on silica gel (Table 1). GC analysis
of the reaction mixture showed complete conversion of
3a to 4a with no other products detected. The catalyst
loading could be reduced to 1 mol % without compromis-
ing reaction time or yield of dioxolane (entry 2). Reducing
the amount of catalyst to 0.1 mol %, however, resulted
in incomplete conversion of the epoxide after refluxing
the mixture overnight. A variety of monosubstituted
† Henry Dreyfus Teacher-Scholar 2003.
(1) Green, T. W.; Wuts, P. in Protective Groups in Organic Synthesis,
2nd ed.; J ohn Wiley & Sons: New York, 1991, 123-125.
(2) Larock, R. C. Comprehensive Organic Transformations, 2nd ed.;
Wiley-VCH: New York, 1999.
(3) Torok, D.; Figueroa, J .; Scott, W. J . Org. Chem. 1993, 58, 7274-
7276.
(4) Bogert, M.; Roblin, R. J . Am. Chem. Soc. 1933, 55, 3741-3745.
(5) Hanzlik, R.; Leinwetter, J . J . Org. Chem. 1978, 43, 438-440.
(6) Nagata, T.; Takai, T.; Yamada, T.; Imagawa, K.; Mukaiyama,
T. Bull. Chem. Soc. J pn. 1994, 67, 2614-2616.
(7) Iranpoor, N.; Zeynizadeh, B. J . Chem. Res. (S) 1998, 466-467.
(8) Habibi, M.; Tangestaninejad, S.; Mirkhani, V.; Yadollahi, B.
Catal. Lett. 1975, 3-4, 205-207.
(9) Adams, R.; Barnard, T.; Brosius, K. J . Organomet. Chem. 1999,
582, 358-361.
(16) Zatorski, L. W.; Wierzchowski, P. T. Catal. Lett. 1991, 10, 211-
214.
(10) Iranpoor, N.; Kazemi, F. Synth. Commun. 1998, 28, 3189-3193.
(11) Busci, I.; Meleg, A.; Molna´r, A.; Barto´k, M. J . Mol. Catal. 2001,
168, 47-52.
(17) Vyvyan, J . R.; Staben, S. T. Unpublished results. Characteriza-
tion data for acetonide 2: IR (neat, NaCl): 3385 (br s), 1618, 1608,
(12) Mohammadpoor-Baltork, I.; Khosropour, A.; Aliyan, H. Synth.
Commun. 2001, 31, 3411-3416.
1592, 1219, 1115, and 752 (m) cm-1 1H NMR (CDCl3, 300 MHz): δ
.
7.17 (m, 1H), 7.11 (m, 1H), 6.78 (td, J ) 7.4, 1.1, 1H), 6.73 (dd, J )
8.1, 1.1, 1H), 3.78 (dd, J ) 9.2, 4.2, 1H), 3.25 (br sextet, J ) 7.0, 1H),
1.80 (m, 2H), 1.65 (m, 1H), 1.35 (s, 3H), 1.31 (s, 3H), 1.30 (m, 1H),
1.21 (d, J ) 7.0, 3H), 1.14 (s, 3H), and 0.97 (s, 3H). 13C NMR (CD3OD,
75 MHz): δ 156.1, 134.4, 128.1, 127.7, 120.8, 116.2, 107.7, 84.9, 81.7,
35.5, 33.9, 28.96, 28.88, 28.2, 26.5, 23.3, and 21.7.
(13) Firouzabadi, H.; Iranpoor, N.; Shaterian, H. Bull. Chem. Soc.
J pn. 2002, 75, 2195-2205.
(14) Tangestaninejad, S.; Habibi, M.; Mirkhani, V.; Moghadam, M.
J . Chem. Res. (S) 2001, 365-367.
(15) Zhu, Z.; Espenson, J . Organometallics 1997, 16, 3658-3663.
10.1021/jo035112y CCC: $25.00 © 2003 American Chemical Society
Published on Web 10/14/2003
9144
J . Org. Chem. 2003, 68, 9144-9147

TABLE 2. Con ver sion of Di- a n d Tr isu bstitu ted
Ep oxid es to Aceton id esa
Reaction of optically pure epoxides under the standard
conditions (acetone, 1 mol % anhydrous SnCl2, reflux)
resulted in significant loss of optical activity in the
products. (R)-(+)-Styrene oxide [(+)-3d , 99% ee] produced
acetonide (+)-4d in 94% yield, but the optical purity had
eroded to 44% ee (eq 2).19 Conducting this reaction at
lower temperature (-78 °C to room temperature) pro-
duced (+)-4d in a slightly improved 55% ee. The enan-
tiomeric excess of the product did not change during the
course of the reaction, however, nor did the enantiomeric
excess change after extended treatment of the product
with SnCl2 in refluxing acetone. To determine to what
extent an SN1-type epoxide opening was occurring, we
next examined epoxides that were not electronically
biased toward formation of a resonance-stabilized cation
intermediate. (S)-(+)-Benzylglycidyl ether [(+)-(3e), 99%
ee] led to acetonide (-)-4e in 92% yield, but the optical
purity had eroded to 65% ee (eq 3).19,20 The major
a
Epoxide was treated with anhydrous SnCl2 (1 mol %) in
b
refluxing acetone for the time period indicated. Isolated yield of
purified material. c 1-Cyclohexenylmethanol also isolated (16%).
d
Reaction conducted at room temperature.
epoxides 3 were then evaluated using the optimized
reaction protocol (Table 1). The yields of dioxolanes 4
range from good to excellent for all substrates; the yield
of dioxolane 4g is lower due to product volatility. Com-
mon alcohol protecting groups such as methoxymethyl
(MOM) ether (3i), benzyl ether (3j), tert-butyldimethyl-
silyl (TBS) ether (3k ), and p-methoxybenzyl (PMB) ether
(3j) are all compatible with the reaction conditions.
Attempts to prepare 1,3-dioxolanes derived from other
ketones (3-pentanone, cyclohexanone) were unsuccessful,
however. Apparently the reaction is sensitive to steric
hindrance with respect to the ketone reaction partner.
Di- and trisubstituted epoxides also participate in the
reaction to yield the corresponding dioxolanes (Table 2).
Spiroepoxide 5 provided the corresponding dioxolane 6
in moderate yield along with 1-cyclohexenylmethanol
from elimination, although no cyclohexanecarboxalde-
hyde, another likely rearrangement product, was de-
tected in this reaction. Cyclohexene oxide (7) provided
only trans-1,2-cyclohexanediol acetonide (8) in moderate
yield, but the reaction had to be done at room tempera-
ture to prevent the formation of an unidentified side
product. Reaction of trans-2,3-epoxyheptane (9) gave only
cis-acetonide 10, and cis-2,3-epoxyheptane (11) provided
only the trans-acetonide 12, respectively.18 The reaction
of epoxide 9 took 3 h to reach completion, presumably
due to the increased steric congestion that occurs after
the epoxide opening. Epoxide 11 was completely con-
sumed in less than 1 h, however, since steric congestion
is released upon epoxide opening in this case. Trisubsti-
tuted epoxide 13 also reacted smoothly under the stan-
dard conditions to yield acetonide 14 in good yield.
enantiomer produced in the reaction of both (+)-3d and
(+)-3e results from attack of acetone at the more sub-
stituted epoxide position with inversion of stereochem-
istry. Treatment of (R)-(+)-1,2-epoxynonane under the
standard conditions formed the corresponding acetonide
with only a 6% enantiomeric excess (not shown). This
result shows that acetone attacks both epoxide positions
with nearly equal frequency when the oxirane is not
electronically biased. Thus the high diastereoselectivity
of this reaction (Table 2, entries 2-4) coupled with the
erosion of optical purity from single enantiomer epoxides
(eqs 2 and 3) supports an SN2-like opening of the epoxide
by acetone that occurs with low regioselectivity.9,21
In summary, we have found that anhydrous SnCl2 is
an efficient catalyst for the conversion of mono-, di-, and
trisubstituted epoxides directly to their 2,2-dimethyl-1,3-
dioxolane derivatives. The reaction is compatible with a
(18) The relative stereochemistry of the dioxolane products was
confirmed by analysis of the 1H-1H coupling constants and their
comparison to literature values: Pihlaja, K.; Nummelin, H.; Klika, K.;
Czombos, J . Magn. Reson. Chem. 2001, 39, 657-671.
(19) Enantiomeric excesses were determined by GC analysis on a
Cyclosil-B chiral column. The absolute configuration of the major
enantiomer was determined by measuring the optical rotation of the
product and correlating it to literature values. For (+)-4d : Schaus, S.
E.; Brandes, B. D.; Larrow, J . F.; Tokunaga, M.; Hansen, K. B.; Gould,
A. E.; Furrow, M. E.; J acobsen, E. N. J . Am. Chem. Soc. 2002, 124,
1307-1315. For (-)-4e: Fondy, T. P.; Pero, R. W.; Karker, K. L.;
Ghangas, G. S.; Batzold, F. H. J . Med. Chem. 1974, 17, 697-702.
(20) A similar decrease in enantiomeric excess with this substrate
has been observed with other Lewis acids. See ref 6.
(21) (a) Blackett, B.; Coxon, J .; Hartshorn, M.; Lewis, A.; Little, G.;
Wright, G. Tetrahedron 1970, 26, 1311-1313. (b) Eisch, J . J .; Liu, Z.-
R.; Ma, X.; Zheng, G.-X. J . Org. Chem. 1992, 57, 5140-5144.
J . Org. Chem, Vol. 68, No. 23, 2003 9145

(ddt, J ) 10.0, 1.8, 1.2, 1H), 4.06 (m, 2H), 3.51 (m, 1H), 2.13 (m,
2H), 1.75 (m, 1H), 1.59 (m, 1H), 1.40 (s, 3H), and 1.35 (s, 3H).
13C NMR (CDCl3, 75 MHz): δ 137.5, 114.7, 108.4, 75.3, 69.2,
32.7, 29.8, 26.8, and 25.6.
variety of common protecting groups but leads to varying
degrees of racemization with optically pure epoxides.
Exp er im en ta l Section 22
4-Vin yl-2,2-dim eth yl-1,3-dioxolan e (4 g).9 Anhydrous SnCl2
(73 mg, 0.39 mmol), acetone (80 mL), and butadiene monoxide
(3g) (3.14 mL, 39 mmol) yielded 4g as a colorless oil (2.401 g,
Gen er a l P r oced u r e. P r ep a r a t ion of 4-H exyl-2,2-d i-
m eth yl-1,3-d ioxola n e (4a ).12 Anhydrous tin(II) chloride (98%)
(9.9 mg, 0.05 mmol) was placed in a two-necked flask (50 or 100
mL) equipped with a magnetic stir bar and a reflux condenser.
The system was sequentially evacuated and filled with argon
six times. Dry acetone (25 mL) was added through the septum
and stirring was started. 1,2-Epoxyoctane (3a ) (0.76 mL, 5.0
mmol) was added dropwise and the solution was heated to reflux
and maintained at that temperature until GC analysis indicated
complete consumption of the epoxide (typically 1 h). The acetone
was removed by rotary evaporation and the residue was taken
up in CH2Cl2 (20 mL), and 10% NaOH solution (10 mL) and
water (5 mL) were added. The layers were separated, and the
aqueous layer was extracted CH2Cl2 (2 × 5 mL). The combined
organic layers were dried over Na2SO4. After solvent removal
via rotary evaporation, the crude product was purified by MPLC
(75:1 hexanes/ethyl acetate) to give 4a (0.919 g, 97%) as a
colorless oil. 1H NMR (CDCl3, 300 MHz): δ 4.05 (m, 2H), 3.49
(m, 1H), 1.7-1.2 (m, 10H), 1.40 (s, 3H), 1.35 (s, 3H), and 0.88 (t,
J ) 7.0, 3H). 13C NMR (CDCl3, 75 MHz): δ 108.4, 76.1, 69.5,
33.6, 31.7, 29.4, 27.0, 25.8 (2C), 22.6, and 14.1.
4-Decyl-2,2-d im eth yl-1,3-d ioxola n e (4b). Anhydrous SnCl2
(9.8 mg, 0.05 mmol), acetone (25 mL), and epoxide 3b (1.10 mL,
5 mmol) yielded 4b (1.117 g, 92%) after MPLC (30:1 hexanes/
ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ 4.05 (m, 2H), 3.49
(m, 1H), 1.7-1.2 (m, 14H), 1.40 (s, 3H), 1.36 (s, 3H), and 0.88 (t,
J ) 7.0, 3H). 13C NMR (CDCl3, 75 MHz): δ 108.2, 75.9, 69.3,
33.5, 31.8, 29.6, 29.5, 29.5, 29.4, 29.3, 26.8, 25.7, 25.6, 22.6, and
14.0. Anal. Calcd for C15H30O2: C, 74.32; H, 12.47. Found: C,
73.97; H, 12.20.
1
48%) after distillation (bp 125 °C). H NMR (CDCl3, 300 MHz):
δ 5.82 (ddd, J ) 17.3, 10.3, 7.3, 1H), 5.34 (ddd, J ) 17.3, 1.5,
1.5, 1H), 5.21 (ddd, J ) 10.3, 1.5, 0.9, 1H), 4.49 (ddddd, J ) 8.2,
7.3, 6.2, 1.5, 0.9, 1H), 4.10 (dd, J ) 6.2, 2.0, 1H), 3.60 (dd, J )
8.2, 6.2, 1H), 1.43 (s, 3H), and 1.40 (s, 3H). 13C NMR (CDCl3, 75
MHz): δ 135.6, 117.6, 109.0, 77.2, 69.1, 26.5, and 25.7.
4-Cycloh exyl-2,2-d im eth yl-1,3-d ioxola n e (4h ). Anhydrous
SnCl2 (9.6 mg, 0.05 mmol), acetone (25 mL), and epoxide 3h
(0.623 g, 5 mmol) yielded 4h as a colorless oil (0.575 g, 63%)
after MPLC (19:1 hexanes: ethyl acetate). 1H NMR (CDCl3, 300
MHz): δ 3.97 (dd, J ) 7.6, 5.8, 1H), 3.78 (dd, J ) 7.6, 5.8, 1H),
3.60 (t, J ) 7.6, 1H), 1.90-0.98 (m, 11H), 1.39 (s, 3H), and 1.35
(s, 3H). 13C NMR (CDCl3, 75 MHz): δ 108.2, 80.2, 67.6, 41.3,
29.4, 28.6, 26.6, 26.3, 25.8, 25.6, and 25.5. Anal. Calcd for
C11H20O2: C, 71.70; H, 10.94. Found: C, 71.54; H, 10.86.
4-(9-Me t h oxym e t h oxyn on yl)-2,2-d im e t h yl-1,3-d ioxo-
la n e (4i). Anhydrous SnCl2 (14 mg, 0.07 mmol), acetone (25 mL),
and epoxide 3i (1.159 g, 5 mmol) yielded 4i (1.101 g, 77%) after
MPLC (15:1 hexanes/ethyl acetate). 1H NMR (CDCl3, 300
MHz): δ 4.60 (s, 2H), 4.05 (m, 2H), 3.50 (m, 3H), 3.38 (s, 3H),
1.7-1.5 (m, 2H), 1.40 (s, 3H), 1.35 (s, 3H), and 1.5-1.3 (m, 14H).
13C NMR (CDCl3, 75 MHz): δ 108.5, 96.3, 76.1, 69.5, 67.8, 55.1,
33.6, 29.8, 29.7, 29.55, 29.51, 29.50, 27.0, 26.3, and 25.8 (2C).
Anal. Calcd for C16H32O4: C, 66.63; H 11.18. Found: C, 66.39;
H, 11.47.
4-(9-Ben zyloxyn on yl)-2,2-dim eth yl-1,3-dioxolan e (4j). An-
hydrous SnCl2 (9.5 mg, 0.05 mmol), acetone (25 mL), and epoxide
3j (1.380 g, 5 mmol) yielded 4j (1.120 g, 67%) after MPLC (12:1
hexanes/ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ 7.3 (m,
5H), 4.5 (s, 2H), 4.0 (m, 2H), 3.45 (m, 3H), 1.7-1.5 (m, 2H), 1.40
(s, 3H), 1.35 (s, 3H), and 1.5-1.2 (m, 14H). 13C NMR (CDCl3),
75 MHz) δ 138.5, 128.1, 127.4, 127.3, 108.4, 76.1, 72.8, 70.4, 69.5,
33.6, 29.8, 29.7, 29.5, 29.46(2C), 27.0, 26.2, and 25.8 (2C). Anal.
Calcd for C21H34O3: C, 75.41; H, 10.25. Found: C, 75.44; H,
10.37.
4-Allyloxym eth yl-2,2-d im eth yl-1,3-d ioxola n e (4c).8 An-
hydrous SnCl2 (9.8 mg, 0.05 mmol), acetone (25 mL), and epoxide
3c (0.59 mL, 5 mmol) yielded 4c (0.818 g, 95%) after MPLC (15:1
hexanes/ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ 5.89 (ddt,
J ) 17.3, 10.3, 5.7, 1H), 5.26 (ddt, J ) 17.3, 1.8, 1.8, 1H), 5.18
(ddt, J ) 10.3, 1.2, 1.2, 1H), 4.28 [tt (app pentet), J ) 6.0, 6.0,
1H], 4.04 (m, 3H), 3.73 (dd, J ) 8.2, 6.4, 1H), 3.48 (m, 2H), 1.43
(s, 3H), and 1.37 (s, 3H). 13C NMR (CDCl3, 75 MHz): δ 134.2,
117.0, 109.1, 74.5, 72.3, 70.9, 66.6, 26.6, and 25.3.
ter t-Bu tyl-[9-(2,2-d im eth yl-1,3-d ioxola n -4-yl)n on yloxy]-
d im eth ylsila n e (4k ). Anhydrous SnCl2 (9.6 mg, 0.05 mmol),
acetone (25 mL) and epoxide 3k (1.50 g, 5 mmol) yielded 4k (1.32
g, 73%) after MPLC (19:1 hexanes/ethyl acetate). 1H NMR
(CDCl3, 300 MHz): δ 4.05 (m, 2H), 3.58 (t, J ) 6.6, 2H), 3.50
(m, 1H), 1.7-1.4 (m, 2H), 1.40 (s, 3H), 1.35 (s, 3H), 1.4-1.2 (m,
14H), 0.85 (s, 9H), and 0.05 (s, 6H). 13C NMR (CDCl3, 75 MHz):
δ 108.4, 76.1, 69.5, 63.3, 33.6, 32.9, 29.7, 29.6, 29.5, 29.4, 27.0,
26.0 (2C), 25.8 (2C), 18.4, and -5.2. Anal. Calcd for C20H42O3Si:
C, 66.98; H, 11.80. Found: C, 66.66; H, 12.14.
2,2-Dim et h yl-4-p h en yl-1,3-d ioxola n e (4d ).5 Anhydrous
SnCl2 (9.6 mg, 0.05 mmol), acetone (25 mL), and epoxide 3d (0.57
mL, 5 mmol) yielded 4d (0.803 g, 90%) after MPLC (50:1
1
hexanes/ethyl acetate). H NMR (CDCl3, 300 MHz): δ 7.33 (m,
5H), 5.06 (dd, J ) 8.0, 6.2, 1H), 4.29 (dd, J ) 8.0, 6.2, 1H), 3.70
(t, J ) 8.0, 1H), 1.55 (s, 3H), and 1.49 (s, 3H). 13C NMR (CDCl3,
75 MHz): δ 138.8, 128.2, 127.7, 125.9, 109.4, 77.8, 71.5, 26.5,
and 25.9.
4-[9-(4-Met h oxyb en zyloxy)n on yl]-2,2-d im et h yl-1,3-d i-
oxola n e (4l). Anhydrous SnCl2 (9.6 mg, 0.05 mmol), acetone
(25 mL), and epoxide 3l (1.82 g, 5.9 mmol) yielded 4l (1.38 g,
2,2-Dim e t h yl-4-[(p h e n ylm e t h oxy)m e t h yl]-1,3-d ioxo-
la n e (4e).23 Anhydrous SnCl2 (9.5 mg, 0.05 mmol), acetone (25
mL), and epoxide 3e (0.76 mL, 5 mmol) yielded 4e (0.886 g, 80%)
1
64%) after MPLC (9:1 hexanes/ethyl acetate). H NMR (CDCl3,
1
after MPLC (12:1 hexanes/ethyl acetate). H NMR (CDCl3, 300
300 MHz): δ 7.24 (m, 2H), 6.85 (m, 2H), 4.42 (s, 2H), 4.05 (m,
2H), 3.79 (s, 3H), 3.6-3.4 (m, 3H), 1.40 (s, 3H), 1.35 (s, 3H),
and 1.7-1.2 (m, 16H). 13C NMR (CDCl3, 75 MHz): δ 158.8, 130.6,
129.1, 113.6, 108.4, 76.1, 72.4, 70.1, 69.5, 55.2, 33.6, 29.8, 29.7,
29.5, 29.47 (2C), 27.0, 26.2, and 25.8 (2C). Anal. Calcd for
C22H36O4: C, 72.49; H, 9.95. Found C, 72.36; H, 10.20.
2,2-Dim eth yl-1,3-d ioxa sp ir o[4.5]d eca n e (6).25 Anhydrous
SnCl2 (9.5 mg, 0.05 mmol), acetone (25 mL), and epoxide 5 (0.56
g, 5 mmol) yielded 6 as a colorless oil (0.488 g, 57%) along with
(1-cyclohexenyl)methanol26 (0.137 g, 16%) after MPLC (19:1
hexanes/ethyl acetate). Characterization data for 6: 1H NMR
(CDCl3, 300 MHz): δ 3.76 (s, 2H), 1.8-1.5 (m, 5H), 1.39 (s, 6H),
and 1.4-1.2 (m, 5H). 13C NMR (CDCl3, 75 MHz): δ 108.3, 80.9,
73.1, 36.5, 27.3, 25.2, and 23.7.
MHz): δ 7.32 (m, 5H), 4.57 (AB, J ) 12.3, 2H), 4.29 [dddd (app
tt), J ) 6.2, 5.6, 1H], 4.05 (dd, J ) 8.2, 6.2), 3.73 (dd, J ) 8.2,
6.5, 1H), 3.55 (dd, J ) 10.0, 5.6, 1H), 3.46 (dd, J ) 10, 5.6, 1H),
1.42 (s, 3H), and 1.36 (s, 3H). 13C NMR (CDCl3, 75 MHz): δ
137.6, 128.1, 127.4 (2C), 109.1, 74.5, 73.3, 70.8, 66.6, 26.6, and
25.3.
4-(3-Bu t en yl)-2,2-d im et h yl-1,3-d ioxola n e (4f).24 Anhy-
drous SnCl2 (9.7 mg, 0.05 mmol), acetone (25 mL), and epoxide
3f (0.56 mL, 5 mmol) yielded 4f (0.556 g, 71%) after MPLC (30:1
hexanes/ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ 5.81 (ddt,
J ) 17.0, 10.3, 6.5, 1H), 5.03 (ddt, J ) 17.0, 1.8, 1.8, 1H), 4.97
(22) For general experimental considerations, see Supporting In-
formation.
(23) Shiao, M.; Yang, C.; Lee, S.; Wu, T. Synth. Commun. 1988, 18,
359-366.
(24) Wipf, P.; Xu, W.; Smitrovich, J .; Lehmann, R.; Venanzi, L.
Tetrahedron 1994, 50, 1935-1954.
(25) J ones, R. A. Y.; Katritzky, A. R.; Nicol, D. L.; Scattergood, R.
J . Chem. Soc., Perkin Trans. 2 1973, 337-338.
(26) Majetich, G.; Song, J . S.; Ringold, C.; Nemeth, G. A.; Newton,
G. M. J . Org. Chem. 1991, 56, 3973-3988.
9146 J . Org. Chem., Vol. 68, No. 23, 2003

Hexah ydr o-2,2-dim eth yl-tr a n s-1,3-ben zodioxole (8).27 An-
hydrous SnCl2 (8.7 mg, 0.05 mmol), acetone (25 mL), and epoxide
7 (0.51 mL, 5 mmol) yielded 8 (0.498 g, 64%) after MPLC (19:1
J ) 7.0 Hz, 3H). 13C NMR (CDCl3, 75 MHz): δ 107.4, 82.4, 76.7,
32.0, 28.3, 27.2 (2C), 22.9, 17.6, and 13.9. Anal. Calcd for
C
10H20O2: C, 69.72; H, 11.70. Found: C, 69.65; H, 11.38.
1
hexanes/ethyl acetate). H NMR (CDCl3, 300 MHz): δ 3.27 (m,
2,2,4,4-Tet r a m et h yl-5-n on yl-1,3-d ioxola n e (14). Anhy-
2H), 2.10 (m, 2H), 1.80 (m, 2H), 1.5-1.3 (m, 8H), and 1.3-1.2
(m, 2H). 13C NMR (CDCl3, 75 MHz): δ 107.8, 79.8, 28.6, 26.7,
and 23.5.
drous SnCl2 (6.0 mg, 0.03 mmol), acetone (10 mL), and epoxide
13 (0.479 g, 2.42 mmol) yielded 14 (0.500 g, 81%) after MPLC
(30:1 hexanes/ethyl acetate). 1H NMR (CDCl3, 300 MHz): δ 3.67
(dd, J ) 8.8, 3.5, 1H), 1.6-1.2 (m, 16H), 1.42 (s, 3H), 1.33 (s,
3H), 1.27 (s, 3H), 1.09 (s, 3H), and 0.88 (t, J ) 7.0, 3H. 13C NMR
(CDCl3, 75 MHz): δ 106.2, 83.3, 80.0, 31.9, 29.8, 29.6, 29.5, 29.4,
29.3, 28.5, 27.0, 26.8, 26.0, 22.8, 22.7, and 14.1. Anal. Calcd for
cis-4-Bu tyl-2,2,5-tr im eth yl-1,3-d ioxola n e (10). Anhydrous
SnCl2 (9.5 mg, 0.05 mmol), acetone (25 mL), and epoxide 9 (0.564
g, 4.9 mmol) yielded 10 (0.426 g, 50%) after MPLC (50:1 hexanes/
ethyl acetate). An analytical sample was prepared by distillation
(bp 72-73 °C, 15 mmHg). 1H NMR (CDCl3, 300 MHz): δ 4.22
(dq, J ) 6.2, 6.2, 1H), 4.02 (m, 1H), 1.6-1.2 (m, 6H), 1.44 (s,
3H), 1.33 (s, 3H), 1.14 (d, J ) 6.4, 3H), and 0.91 (t, J ) 7.0, 3H);
13C NMR (CDCl3, 75 MHz): δ 106.9, 77.9, 73.6, 29.4, 28.5, 28.4,
25.7, 22.6, 15.5, and 13.9. Anal. Calcd for C10H20O2: C, 69.72;
H, 11.70. Found: C, 69.64; H, 11.92.
tr a n s-4-Bu tyl-2,2,5-tr im eth yl-1,3-d ioxola n e (12). Anhy-
drous SnCl2 (9.5 mg, 0.05 mmol), acetone (25 mL), and epoxide
11 (0.570 g, 5.0 mmol) yielded 12 (0.390 g, 45%) after MPLC
(50:1 hexanes/ethyl acetate). An analytical sample was prepared
by distillation (bp 62 °C, 16 mmHg). 1H NMR (CDCl3, 300
MHz): δ 3.70 (dq, J ) 8.2, 6.1, 1H), 3.51 (m, 1H), 1.6-1.2 (m,
6H), 1.39 (s, 3H), 1.38 (s, 3H), 1.24 (d, J ) 6.1, 3H), and 0.91 (t,
C
16H32O2: C, 74.94; H, 12.58. Found: C, 74.86; H, 12.80.
Ack n ow led gm en t. We thank the National Science
Foundation (CHE0094378) and the Herman Frasch
Foundation (522-HF02) for financial support of this
work.
Su p p or tin g In for m a tion Ava ila ble: Experimental pro-
cedures and characterization data for epoxides 3h -l and 13.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(27) Larson, G.; Hernandez, A. J . Org. Chem. 1973, 38, 3935-3936.
J O035112Y
J . Org. Chem, Vol. 68, No. 23, 2003 9147