Olefin cleavage under osmylation conditions

Full text of DOI:10.1021/jo9812983

J . Org. Chem. 1998, 63, 8071-8073
8071
Sch em e 1
Olefin Clea va ge u n d er Osm yla tion
Con d ition s
Hon-Chung Tsui and Leo A. Paquette*
Evans Chemical Laboratories, The Ohio State University,
Columbus, Ohio 43210
Received J uly 6, 1998
The reliability of osmium tetraoxide for accomplishing
the cis-dihydroxylation of alkenes is unrivaled.1-3 Fur-
thermore, the ability to accomplish cyclic osmate(VI)
ester formation in a diastereoselective4,5 and enantiose-
lective manner6 has provided considerable impetus to the
widespread application of this reagent in synthesis. If
desired, higher level oxidation to give carbonyl products
is customarily accomplished by the coaddition of oxidants
such as sodium periodate7,8 or hydrogen peroxide,9 but
not otherwise.
During the course of a study designed to explore the
reversibility of anionic oxy-Cope rearrangements in the
context of taxoid synthesis, we developed routes to the
bridgehead olefinic ketones 1 and 4.10 In pursuit of
certain objectives, subsequent occasion arose to bring
their derivatives 2 and 5 into reaction with osmium
tetraoxide. Both systems react sluggishly with this
reagent, thereby requiring somewhat more forcing condi-
tions than is customary. We report herein that both
reactions lead to the respective keto aldehyde following
appropriate reduction. To our knowledge, no observation
of comparable cleavage capability with OsO4 has previ-
ously been detailed.
Sch em e 2
The ready reduction of 1 with sodium borohydride in
methanol is shown in Scheme 1. Diol production in this
manner proceeded with excellent stereoselectivity to
1
produce a single diastereomer. Neither its high-field H
NMR spectrum nor that of the derived diacetate 2
provided unequivocal confirmation of the configuration
set at the new stereogenic center, and this issue was
therefore not pursued. This difficulty stems in part from
complexities arising from slow atropisomeric equilibra-
tion on the NMR time scale near room temperature. For
example, 2 exists as a 1:1 mixture of two conformational
isomers under conventional operating conditions. Sa-
ponification of 2 with aqueous sodium hydroxide in
methanol returned uniquely the original diol.
(1) Scho¨der, M. Chem. Rev. 1980, 80, 187.
When preliminary attempts to dihydroxylate the bridge-
head olefinic bond in 2 with osmium tetraoxide under
catalytic conditions gave little evidence of reaction,
recourse was eventually made to somewhat greater than
stoichiometric quantities of the reagent in pyridine
solution at 90 °C. When this measure was taken, 2 was
completely consumed within 2 h. However, subsequent
decomposition of the osmate complex with sodium dithio-
nite or hydrogen sulfide produced not the expected diol
but keto aldehyde 3 instead. The diagnostic spectral
features of 3 include, but are hardly limited to, an
aldehyde proton signal at δ 9.74 (d, J ) 2.6 Hz) and two
carbonyl carbons at 222.3 and 201.9 ppm.
(2) Singh, H. S. In Organic Synthesis by Oxidation with Metal
Compounds; Mijs, W. J ., De J onge, C. R. H. I., Eds.; Plenum: New
York, 1986; Chapter 12.
(3) Fieser, L. F.; Fieser, M. Reagents for Organic Synthesis; J ohn
Wiley and Sons: New York, 1967; pp 759-764.
(4) Haines, A. H. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Eds.; Pergamon Press: Oxford, U.K., 1991; Volume 7,
Chapter 3.3.
(5) Gao, Y. In Encyclopedia of Reagents for Organic Synthesis;
Paquette, L. A., Ed.; J ohn Wiley and Sons: Chichester, U.K., 1995;
Vol. 6, pp 3801-3805.
(6) J ohnson, R. A.; Sharpless, K. B. In Catalytic Asymmetric
Synthesis; Ojima, I., Ed.; VCH: New York, 1993.
(7) Haines, A. H. In Methods for the Oxidation of Organic Com-
pounds; Academic Press: Toronto, 1985; p 117.
(8) (a) Lee, D. G. In Oxidation Techniques and Applications in
Organic Synthesis; Augustine, R. L., Ed.; Marcel Dekker: New York,
1969; Vol. 1. (b) Lee, D. G.; Chen, T. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford,
U.K., 1991; Vol. 7, Chapter 3.8.
Comparable behavior was exhibited by 5 (Scheme 2).
This aspect of the investigation was made possible by the
smooth conversion of 410 into the R-alcohol by reduction
with lithium aluminum hydride in ether and subsequent
formation of the p-methoxybenzyl ether. In this instance,
(9) Milas, N. A.; Trepagnier, J . H.; Nolan, J . T., J r.; Iliopulos, M. I.
J . Am. Chem. Soc. 1959, 81, 4730.
(10) Tsui, H.-C.; Paquette, L. A. Submitted for publication.
10.1021/jo9812983 CCC: $15.00 © 1998 American Chemical Society
Published on Web 09/30/1998

8072 J . Org. Chem., Vol. 63, No. 22, 1998
Notes
171.1, 170.2, 170.0, 169.7, 144.8, 143.3, 139.2, 128.4 (2 C), 128.3
(2 C), 127.5 (4 C), 127.3, 126.9 (2 C), 120.1, 118.2, 99.9, 95.6,
95.3, 86.9, 86.5, 85.8, 83.5, 83.2, 81.2, 79.0, 77.8, 75.4, 74.9, 73.8,
71.9, 65.32, 65.27, 58.9 (2 C), 55.7, 55.4, 52.9, 51.4, 48.5, 47.1,
45.6, 44.4, 38.4, 34.9, 34.6, 34.2, 27.3, 27.1, 25.9 (6 C), 25.2, 24.9,
24.5, 22.2, 21.7, 21.3, 21.21, 21.17, 20.6 (2 C), 20.4, 18.3, 13.8,
-5.19, -5.26 (2 C), -5.31; FAB MS m/z (M+ + H) calcd 689.41,
obsd 689.33.
stereochemistry was directly revealed by NOE difference
experiments. Suggested by this stereochemical outcome
is the preferred adoption by 4 of a “carbonyl-down”
conformation, with the hydride reagent then attacking
from the less hindered π-surface.
When 5 was subjected to analogous osmylating condi-
tions, comparable conversion to 6 was similarly noted.
On this basis, it would seem possible that the elevated
temperatures utilized promote reaction beyond the usual
formation of A. Cleavage of the C-C bond with insertion
(rS ,2R ,3S )-3-(Be n zyloxy)-2-[2-(t er t -b u t yld im e t h ylsil-
oxy)eth yl]-r-[1R,2R,4R)-4-[(S)-2,2-d im eth yl-3-oxocyclop en -
tyl]-2,3-d ih yd r oxy-4-(m eth oxym eth oxy)-1-m eth ylbu tyl]-3-
oxeta n ea ceta ld eh yd e Dia ceta te (3). To a solution of 2 (10
mg, 0.017 mmol) in pyridine (0.10 mL) was added osmium
tetraoxide (6.5 mg, 0.026 mmol) in pyridine (0.10 mL). The
mixture was heated at 90 °C for 2 h, and the solvent was
removed in vacuo. Column chromatography of the residue on
silica gel (elution with 2:3 hexanes-ethyl acetate) gave a
dipyridylosmium complex as a brown colored oil: IR (film, cm-1
)
1
1739; H NMR (300 MHz, CDCl3) δ 8.75-8.73 (m, 4 H), 7.85-
7.70 (m, 2 H), 7.45-7.15 (m, 9 H), 5.67 (d, J ) 3.5 Hz, 1H), 5.28
(dd, J ) 12.2, 3.3 Hz, 1 H), 5.07 (d, J ) 8.5 Hz, 1 H), 4.93 (d, J
) 12.3 Hz, 1 H), 4.86 (d, J ) 12.3 Hz, 1 H), 4.79 (d, J ) 6.7 Hz,
1 H), 4.70 (d, J ) 8.3 Hz, 1 H), 4.64-4.59 (m, 2 H), 4.48 (dd, J
) 9.9, 2.9 Hz, 1 H), 4.05 (d, J ) 8.5 Hz, 1 H), 3.70-3.63 (m, 1
H), 3.44 (s, 3 H), 2.80-2.67 (m, 3 H), 2.44-2.21 (m, 2 H), 2.17-
1.90 (m, 4 H), 2.05 (s, 3 H), 2.01 (s, 3 H), 1.41 (s, 3 H), 1.39 (s,
3 H), 0.89 (d, J ) 7.3 Hz, 3 H), 0.82 (s, 9 H), -0.026 (s, 3 H),
-0.030 (s, 3 H); 13C NMR (75 MHz, CDCl3, ppm) 170.9, 169.6,
149.6 (4 C), 140.3, 139.5 (2 C), 128.1 (4 C), 126.6 (2 C), 126.4,
124.6 (2 C), 100.0, 96.1, 92.9, 90.0, 86.5, 82.9, 75.5, 73.8, 71.6,
63.4, 60.2, 55.5, 54.8, 50.0, 42.6, 36.6, 35.8, 30.6, 30.1, 26.1 (3
C), 23.4, 21.5, 21.0, 20.7, 18.5, 11.4, -5.09, -5.12.
of an oxygen atom as depicted in B would set the stage
for direct keto aldehyde production during reductive
workup. Our attempts to obtain crystalline samples of
the osmate intermediates for X-ray crystallographic
analysis were to no avail. Notwithstanding, these results
provide unambiguous evidence that olefinic cleavage can
indeed occur during osmylation.
Exp er im en ta l Section
(1S,2R,4R,5R,6S,7E)-6-[(2R,3S)-3-(Ben zyloxy)-2-[2-(ter t-
b u t y ld im e t h y ls ilo x y )e t h y l]-3-o x e t a n y l]-2-(m e t h o x y -
m et h oxy)-5,11,11-t r im et h ylb icyclo[6.2.1]u n d ec-7-en e-3,4-
d iol Dia ceta te (2). To a solution of 110 (60 mg, 0.10 mmol) in
methanol (2 mL) at 0 °C was added sodium borohydride (19 mg,
0.50 mmol). The mixture was allowed to warm slowly to room
temperature, stirred for 2 h, quenched with saturated NaHCO3
solution, and diluted with ether. The separated aqueous layer
was extracted further with ether (×2). The combined organic
layers were dried, filtered, and evaporated, followed by chro-
matography on silica gel (elution with 1:1 hexanes-ethyl
acetate). There was isolated 50 mg (83%) of the diol as a
colorless oil: IR (film, cm-1) 3483; 1H NMR (300 MHz, CDCl3) δ
7.48-7.22 (m, 5 H), 5.83 (d, J ) 11.3 Hz, 1 H), 5.04-4.95 (m, 3
H), 4.76-4.63 (m, 4 H), 4.50 (s, 1 H), 3.88 (t, J ) 3.0 Hz, 1 H),
3.81 (d, J ) 5.0 Hz, 1 H), 3.75-3.58 (m, 2 H), 3.52 (dd, J ) 9.5,
3.0 Hz, 1 H), 3.47 (s, 3 H), 3.07 (d, J ) 9.6 Hz, 1 H), 2.92 (dd, J
) 11.5, 7.5 Hz, 1 H), 2.49-2.40 (m, 2 H), 2.24-1.90 (m, 6 H),
1.29 (s, 3 H), 1.07 (s, 3 H), 1.05 (d, J ) 7.4 Hz, 3 H), 0.86 (s, 9
H), -0.01 (s, 6 H); 13C NMR (75 MHz, CDCl3, ppm) 140.6, 139.7,
128.3 (2 C), 127.0, 126.7 (2 C), 121.4, 98.2, 96.7, 87.4, 86.8, 83.5,
77.0, 70.1, 65.6, 59.1, 56.2, 52.0, 48.2, 45.4, 38.3, 35.1, 27.5, 25.9
(3 C), 24.6, 22.9, 21.6, 20.4, 18.3, -5.32, -5.34; FAB MS m/z
(M+ + H) calcd 605.21, obsd 605.26; [R]21D -103 (c 0.84, CHCl3).
A solution of this diol (50 mg, 0.083 mmol) in CH2Cl2 (2 mL)
was treated with triethylamine (0.092 mL, 0.66 mmol), acetic
anhydride (0.039 mL, 0.41 mmol), and a catalytic amount of
4-(N,N-dimethylamino)pyridine. After being stirred at room
temperature for 3 h, the mixture was quenched with saturated
NaHCO3 solution and diluted with ether. The separated aque-
ous layer was further extracted with ether (×2), and the
combined organic extracts were dried and filtered. Removal of
the solvents from the filtrate in vacuo followed by column
chromatography on silica gel (elution with 3:1 hexanes-ethyl
acetate) gave an inseparable pair of conformers of 2 (50 mg, 88%)
as a colorless oil: IR (film, cm-1) 1733; 1H NMR (300 MHz,
CDCl3) δ 7.39-7.25 (m, 10 H), 5.68 (d, J ) 10.6 Hz, 1 H), 5.37
(d, J ) 10.8 Hz, 1 H), 5.15 (t, J ) 3.0 Hz, 1 H), 5.10-4.89 (m, 10
H), 4.80-4.67 (m, 4 H), 4.48 (s, 2 H), 4.46 (s, 2 H), 3.76-3.58
(m, 6 H), 3.31 (s, 3 H), 3.30 (s, 3 H), 3.02 (dd, J ) 11.4, 6.6 Hz,
1 H), 2.93 (t, J ) 10.5 Hz, 1 H), 2.85-2.55 (m, 2 H), 2.30-2.09
(m, 5 H), 2.07 (s, 3 H), 2.03-2.06 (m, 2 H), 2.02 (s, 3 H), 2.01-
1.89 (m, 4 H), 1.81 (s, 3 H), 1.67 (s, 3 H), 1.65-1.58 (m, 2 H),
1.35 (s, 3 H), 1.31 (s, 3 H), 1.09 (s, 3 H), 1.07 (s, 3 H), 1.00 (d, J
) 7.4 Hz, 3 H), 0.88 (s, 9 H), 0.87 (s, 9 H), 0.63 (d, J ) 7.1 Hz,
3 H), 0.04 (s, 6 H), 0.03 (s, 6 H); 13C NMR (75 MHz, CDCl3, ppm)
The brown colored oil from above was dissolved in ethyl
acetate (2 mL), and 20% aqueous sodium dithionite (2 mL) was
added. The mixture was stirred at room temperature for 2 h,
water and ether were added, and the separated aqueous layer
was extracted with ether (×2), dried, and filtered. Concentration
of the filtrate followed by chromatography on silica gel (elution
with 2:1 hexanes-ethyl acetate) gave 3 (5.0 mg, 41%) as a
colorless oil: IR (film, cm-1) 1741; 1H NMR (300 MHz, CDCl3) δ
9.74 (d, J ) 2.6 Hz, 1 H), 7.38-7.27 (m, 5 H), 5.37 (dd, J ) 8.1,
1.6 Hz, 1 H), 5.28 (dd, J ) 8.1, 1.3 Hz, 1 H), 5.18 (dd, J ) 10.8,
2.3 Hz, 1 H), 5.05 (d, J ) 12.1 Hz, 1 H), 4.94 (d, J ) 12.1 Hz, 1
H), 4.79 (d, J ) 8.3 Hz, 1 H), 4.71 (d, J ) 7.1 Hz, 1 H), 4.58 (d,
J ) 8.5 Hz, 1 H), 4.51 (d, J ) 7.1 Hz, 1 H), 3.77-3.63 (m, 2 H),
3.33 (s, 3 H), 2.87 (dd, J ) 8.5, 2.6 Hz, 1 H), 2.63-2.56 (m, 1 H),
2.39-2.29 (m, 1 H), 2.08 (s, 3 H), 2.07 (s, 3 H), 2.17-1.81 (m, 7
H), 1.06 (s, 3 H), 0.93-0.86 (m, 15 H), 0.03 (s, 6 H); 13C NMR
(75 MHz, CDCl3, ppm) 222.3, 201.9, 169.92, 169.88, 138.3, 128.7
(2 C), 127.6, 126.8 (2 C), 96.6, 85.6, 83.6, 76.2, 73.0, 72.0, 65.5,
58.2, 56.8, 56.7, 47.8, 47.3, 35.8, 35.7, 32.0, 25.93, 25.89 (4 C),
24.5, 21.0, 20.9, 18.4, 18.3, 11.7, -5.4, -5.5; FAB MS m/z (M+
+ H) calcd 721.40, obsd 721.28; [R]21 +84 (c 0.08, CHCl3).
D
2-[(2R,3S)-3-(Ben zyloxy)-3-[(1E,3R,4S,6R,7R,8S)-6-[(p -
m e t h oxyb e n zyl)oxy]-7-(m e t h oxym e t h oxy)-4,11,11-t r i-
m et h ylb icyclo[6.2.1]u n d ec-1-en -3-yl]-2-oxet a n yl]et h oxy]-
ter t-bu tyld im eth ylsila n e (5). To a solution of 410 (61 mg, 0.10
mmol) in ether (0.5 mL) at 0 °C was added lithium aluminum
hydride (12 mg, 0.32 mmol). The cooling bath was removed, and
the mixture was allowed to stir at room temperature for 3 h,
cooled to 0 °C, and quenched with saturated NH4Cl solution.
Water and ether were added, and the separated aqueous layer
was extracted with ether (×2). The combined organic extracts
were dried and filtered. Removal of solvents from the filtrate
in vacuo followed by chromatography on silica gel (elution with
2:1 hexanes-ethyl acetate) gave a single diastereoisomeric
alcohol (53 mg, 86%) as a colorless oil: IR (film, cm-1) 3480; 1H
NMR (300 MHz, CDCl3) δ 7.41-7.28 (m, 5 H), 5.16 (d, J ) 11.3
Hz, 1 H), 5.05-4.96 (m, 3 H), 4.81 and 4.77 (ABq, J ) 7.8 Hz, 2
H), 4.64 and 4.61 (ABq, J ) 6.7 Hz, 2 H), 3.77-3.60 (m, 2 H),
3.47 (d, J ) 4.9 Hz, 1 H), 3.39 (s, 3 H), 3.33-3.29 (m, 1 H), 2.93
(d, J ) 9.8 Hz, 1 H), 2.80 (dd, J ) 11.6, 7.7 Hz, 1 H), 2.49-2.41
(m, 1 H), 2.36-2.23 (m, 2 H), 2.22-1.95 (m, 5 H), 1.38-1.30 (m,
1 H), 1.28 (s, 3 H), 1.12 (d, J ) 7.0 Hz, 3 H), 1.05 (s, 3 H), 1.03-
0.90 (m, 1 H), 0.86 (s, 9 H), 0.02 (s, 6 H); 13C NMR (75 MHz,
CDCl3, ppm) 143.4, 139.7, 128.3 (2 C), 127.1, 126.6 (2 C), 121.8,
98.3, 95.0, 86.6, 83.8, 76.8, 68.3, 65.4, 59.0, 55.7, 52.8, 47.7, 46.0,

Notes
J . Org. Chem., Vol. 63, No. 22, 1998 8073
41.2, 35.2, 30.9, 27.3, 25.9 (3 C), 25.8, 23.0, 22.9, 21.4, 18.3,
(m, 1 H), 3.43 (s, 3 H), 3.41-3.35 (m, 1 H), 2.76 (t, J ) 8.8 Hz,
1 H), 2.52 (d, J ) 10.6 Hz, 1 H), 2.26-2.02 (m, 3 H), 1.87-1.54
(m, 4 H), 1.37 (s, 3 H), 1.36 (s, 3 H), 1.32-1.21 (m, 2 H), 0.94 (d,
-5.32, -5.35; FAB MS m/z (M+ + H) calcd 589.39, obsd 589.18;
[R]23 -121 (c 1.29, CHCl3).
D
A suspension of sodium hydride (4.0 mg, 0.16 mmol) in THF
(1 mL) cooled to 0 °C was treated with a solution of the above
alcohol (48 mg, 0.082 mmol) in DMF (0.5 mL). The mixture was
stirred at 0 °C for 15 min whereupon a mixture of p-methoxy-
benzyl chloride (26 mg, 0.16 mmol) and a catalytic amount of
tetra-n-butylammonium iodide in DMF (0.5 mL) were intro-
duced. The mixture was warmed to room temperature, stirred
for another 2 h, returned to 0 °C, and quenched with saturated
NH4Cl solution. Water and ether were added, and the separated
aqueous layer was extracted with ether (×2). The combined
organic extracts were dried and filtered. Solvent evaporation
followed by column chromatography on silica gel (elution with
5:1 hexanes-ether) afforded 5 (46 mg, 79%) as a colorless oil:
IR (film, cm-1) 1613; 1H NMR (300 MHz, CDCl3) δ 7.41-7.22
(m, 7 H), 6.88-6.83 (m, 2 H), 5.20 (d, J ) 11.6 Hz, 1 H), 5.05-
4.95 (m, 3 H), 4.78 (s, 2 H), 4.68 and 4.66 (ABq, J ) 6.5 Hz, 1H),
4.49 (d, J ) 10.2 Hz, 1 H), 4.19 (d, J ) 10.1 Hz, 1 H), 3.91 (d, J
) 4.4 Hz, 1 H), 3.79 (s, 3 H), 3.78-3.61 (m, 2 H), 3.35 (s, 3 H),
3.08 (d, J ) 3.6 Hz, 1 H), 2.76 (dd, J ) 11.6, 8.0 Hz, 1 H), 2.55-
2.12 (m, 6 H), 2.03-1.97 (m, 2 H), 1.34 (s, 3 H), 1.34-1.24 (m,
2 H), 1.08 (s, 3 H), 1.02 (d, J ) 7.0 Hz, 3 H), 0.87 (s, 9 H), 0.03
(s, 6 H); 13C NMR (75 MHz, CDCl3, ppm) 159.1, 143.3, 139.6,
130.6, 129.5 (2 C), 128.3 (2 C), 127.1, 126.6 (2 C), 122.0, 113.7
(2 C), 95.7, 86.6, 83.7, 82.0, 77.7, 76.9, 69.8, 65.3, 59.0, 55.3, 55.2,
51.3, 48.0, 46.1, 37.6, 35.2, 31.0, 27.4, 26.0, 25.9 (3 C), 23.1, 22.7,
21.5, 18.3, -5.3, -5.4; FAB MS m/z (M+ + H) calcd 709.45, obsd
J ) 7.3 Hz, 3 H), 0.83 (s, 9 H), -0.02 (s, 3 H), -0.04 (s, 3 H); 13
C
NMR (75 MHz, CDCl3, ppm) 159.2, 149.6 (4 C), 140.4, 139.4 (2
C), 130.7, 129.3 (2 C), 128.0 (4 C), 126.5 (2 C), 126.4, 124.5 (2
C), 113.9 (2 C), 100.3, 96.1, 93.4, 90.2, 86.7, 83.4, 75.9, 75.8, 70.0,
63.4, 60.1, 55.5, 55.2, 53.5, 50.1, 43.1, 38.4, 36.7, 36.0, 30.6, 26.1
(3 C), 25.7, 23.5, 21.3, 18.5, 18.4, -5.1, -5.2.
The brown colored oil was dissolved in ethyl acetate (2 mL),
and 20% sodium dithionite solution (2 mL) was added. The
mixture was stirred at room temperature for 2 h, water and
ether were introduced, and the separated aqueous layer was
extracted with ether (×2), dried, and filtered. Solvent evapora-
tion followed by chromatography on silica gel (elution with 4:1
hexanes-ethyl acetate) furnished 6 (10 mg, 48%) as a colorless
oil: IR (film, cm-1) 1738, 1722; 1H NMR (300 MHz, CDCl3) δ
9.74 (d, J ) 3.7 Hz, 1 H), 7.33-7.26 (m, 5 H), 7.20 (d, J ) 8.6
Hz, 2 H), 6.82 (d, J ) 8.6 Hz, 2 H), 5.16 (dd, J ) 10.2, 3.0 Hz, 1
H), 4.99 and 4.91 (ABq, J ) 11.8 Hz, 2 H), 4.81 (d, J ) 8.3 Hz,
1 H), 4.80 (d, J ) 6.7 Hz, 1 H), 4.71 (d, J ) 11.0 Hz, 1 H), 4.55
(d, J ) 8.3 Hz, 1 H), 4.50 (d, J ) 6.7 Hz, 1 H), 4.32 (d, J ) 11.0
Hz, 1 H), 3.79 (s, 3 H), 3.74-3.55 (m, 3 H), 3.34 (s, 3 H), 3.27 (d,
J ) 13.7 Hz, 1 H), 2.64 (dd, J ) 5.9, 3.8 Hz, 1 H), 2.42-1.75 (m,
8 H), 1.26-1.00 (m, 2 H), 0.98 (s, 3 H), 0.93 (s, 3 H), 0.87 (s, 12
H), 0.03 (s, 6 H); 13C NMR (75 MHz, CDCl3, ppm) 222.5, 204.1,
159.3, 138.4, 130.4, 129.4 (2 C), 128.4 (2 C), 127.5, 127.0 (2 C),
113.8 (2 C), 97.3, 85.6, 84.0, 78.6, 78.1, 75.4, 71.9, 65.4, 59.7,
58.4, 56.3, 55.3, 47.9, 47.4, 36.0, 35.6, 34.2, 27.7, 25.9 (3 C), 24.3,
22.1, 18.6, 18.4, 18.3, -5.4, -5.5; FAB MS m/z (M+ + H) calcd
709.15; [R]23 -110 (c 1.09, CHCl3).
D
741.44, obsd 741.38; [R]23 +11 (c 0.35, CHCl3).
(rS,2R,3S)-3-(Ben zyloxy)-2-[2-(ter t-bu tyld im eth ylsiloxy-
)eth yl]-r-[1S,3R,4S)-4-[(S)-2,2-d im eth yl-3-oxocyclop en tyl]-
3-[(p-m eth oxyben zyl)oxy]-4-(m eth oxym eth oxy)-1-m eth yl-
bu tyl]-3-oxeta n ea ceta ld eh yd e Dia ceta te (6). A solution of
5 (20 mg, 0.028 mmol) in pyridine (0.10 mL) was treated with
osmium tetroxide (0.10 mL of 0.33 M in pyridine, 0.034 mmol).
The mixture was heated at 90 °C for 2 h, the solvent was
evaporated, and the residue was subjected to chromatography
on silica gel (elution with 1:1 hexanes-ethyl acetate) to leave a
D
Ack n ow led gm en t. We thank the National Cancer
Institute and Hoechst Marion Roussel for their partial
financial support of this research.
Su p p or tin g In for m a tion Ava ila ble: Copies of the 300
MHz NMR spectra of all new compounds (6 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
dipyridylosmium complex as a brown colored oil: IR (film, cm-1
)
2953, 2930, 2855, 1608, 1512, 1450, 1250, 1049, 1068, 1034, 982,
830; 1H NMR (300 MHz, CDCl3) δ 8.77-8.66 (m, 4 H), 7.77-
7.22 (m, 2 H), 7.45-7.15 (m, 11 H), 6.93-6.88 (m, 2 H), 4.95-
4.75 (m, 4 H), 4.72-4.70 (m, 2 H), 4.60-4.43 (m, 4 H), 4.15 (d,
J ) 8.5 Hz, 1 H), 3.88-3.82 (m, 1 H), 3.80 (s, 3 H), 3.66-3.56
J O9812983