6
40
D. W. Knight et al. / Tetrahedron Letters 51 (2010) 638–640
8.
Gallou, F.; Saim, S.; Koenig, K. J.; Bochniak, D.; Horhota, S. T.; Yee, N. K.;
Senanayake, C. H. Org. Process Res. Dev. 2006, 10, 937–940.
9. Michrowska, A.; Gulajski, L.; Kaczmarska, Z.; Mennacke, K.; Kirschning, A.;
Grela, K. Green Chem. 2006, 8, 685–688.
0. Galan, B. R.; Kalbarczyk, K. P.; Szczepankiewicz, S.; Keister, J. B.; Diver, S. T. Org.
Lett. 2007, 9, 1203–1206.
1. Hong, S. H.; Grubbs, R. H. Org. Lett. 2007, 9, 1955–1957.
12. Paquette, L. A.; Schloss, J. D.; Efremov, I.; Fabris, F.; Gallou, F.; Mendez-Andino,
MesN
NMes
Ph
H O
2
2
Cl
Cl
RuO
2
+
Cy P=O
+
PhCO H
2
3
Ru
1
PCy3
+
MesN
NMes (?)
1
2
; Grubbs Mark II
O
J.; Yang, J. Org. Lett. 2000, 2, 1259–1261.
1
1
3. Clavier, H.; Grela, K.; Kirschning, A.; Mauduit, M.; Nolan, S. P. Angew. Chem., Int.
Ed. 2007, 46, 6786–6801.
4. Proctor, A. J.; Knight, D. W.; Beautement, K.; Clough, J. M.; Li, Y.-F. Tetrahedron
Lett. 2006, 47, 5151–5154.
RuO2
2
.H O
2.H O + O2
2
2
2
1
1
5. Knight, D. W.; Morgan, I. R. Tetrahedron Lett. 2009, 50, 35–38.
6. Diisopropyl (2E,14E)-hexadec-2,14-dienoate [5; R = Pr]: Cyclododecene (4)
Scheme 4. A proposed overall reaction scheme for the decomposition of Grubbs
metathesis catalysts.
i
(
1.85 ml, 9.02 mmol) was dissolved in dry dichloromethane (90 ml) and
isopropyl acrylate (2.31 ml, 18.04 mmol) was added dropwise followed by
Grubbs Mark II catalyst (28 mg, 33 mmol). The resulting solution was gently
l
as a slow stream. In our view, this should be an easily scalable meth-
od, given due attention to the formation of oxygen, which surely can
be readily controlled at a perfectly safe level.
refluxed under dry nitrogen for 16 h then cooled in an ice bath and stirred open
to the air. Water (17 ml) followed by 30% aqueous hydrogen peroxide (17 ml,
0.165 mol) was added and the biphasic mixture was stirred vigorously for 1 h
at this temperature. The mixture soon began to effervesce with increasing
vigour (use a large flask) before gradually subsiding, usually during around 15–
Given the cheapness of hydrogen peroxide, together with the
fact that no by-products are produced during the oxidation which
require any separation, we contend that this method should find
many applications on both small scale and large scale, the latter
after some further development. Indeed, given that it is easy to
separate the ruthenium dioxide, which is produced most likely as
a hydrate, this might be regarded as a ‘green’ method and will cer-
tainly be amenable to the easy isolation and re-use of the ruthe-
nium dioxide, which is not a particularly cheap reagent.
20 min. (Caution: oxygen released), as a blue–black precipitate formed. The
mixture was then transferred to a separating funnel and the layers were
separated. The aqueous layer was extracted with dichloromethane (2 Â 30 ml)
and the combined organic solutions checked for peroxide content using damp
starch–iodine paper. Usually this test was negative; if positive, then the
solution was washed with aqueous sodium sulfite until a negative test was
observed. Typically, a single wash was sufficient. The organic solution was then
4
dried (MgSO ) and filtered through a small plug of silica gel. The combined
filtrate and dichloromethane washings were then evaporated to leave the
i
diester [5; R = Pr] (2.67 g, 81%) as a colourless oil, which showed spectroscopic
and analytical data identical to those reported previously:11
d
H
(400 MHz;
In terms of group and compound compatibility, dilute aqueous
hydrogen peroxide is a relatively innocuous reagent and will not
attack many functionalities, especially during the brief exposure
CDCl
- and 15-H), 5.05 (2H, app. hept., J = 6.2 Hz, 2 Â PrCH), 2.20 (4H, app. qd,
J = ca. 6.9, 1.4 Hz, 4- and 13-CH ), 1.50–1.40 (4H, m), 1.30–1.20 (12H, m), 1.26
3
) 6.95 (2H, dt, J = 15.6, 6.3 Hz, 3- and 14-H), 5.88 (2H, dt, J = 15.6, 1.4 Hz,
i
2
2
1
4
+
(
12H, d, J = 6.2 Hz, 4 Â Me); m/z [APCI] 367 (M+H , 100%).
under these neutral conditions required here. In our earlier work,
1
1
7. Beauliev, N.; Deslongchamps, P. Can. J. Chem. 1980, 58, 875–877.
we showed that 1,3-dithiane was not oxidized by exposure to 15%
aqueous hydrogen peroxide during around 10–15 min at ambient
temperature, approximately the conditions used here. No doubt
there will be some incompatibilities but we anticipate that these
will be very few.
8. Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett. 1999, 1, 953–956.
19. Dimethyl cyclopent-3-en-1,1-dicarboxylate 7: A solution of the diallyl diester 617
(0.25 g, 1.18 mmol) in dry dichloromethane (250 ml) was degassed by passing
a stream of dry nitrogen through it for 0.5 h. Grubbs’ Mark I catalyst 1 (49 mg,
59 lmol) was added in one portion and the resulting mixture stirred under dry
nitrogen for 1 h at ambient temperature when tlc monitoring indicated
completion of the reaction. The mixture was opened to the air and stirred
vigorously as water (30 ml) followed by 30% aqueous hydrogen peroxide
Acknowledgements
(
30 ml, 0.295 mol) were added. Vigorous stirring of the resulting biphasic
mixture was continued as effervescence increased during the first 10–15 min
before subsiding, as a blue–black precipitate formed. After 1 h, a starch–iodine
test was negative and the mixture was worked up as described in Ref. 16 to
We are grateful to Miss Sarah C. Heasman and Miss Lisa E.
Knight for experimental assistance, to Dr. Ian McDonald (Earth
and Ocean Sciences, Cardiff University) for provision of the ICPMS
analyzes, to Professor J. M. Clough for helpful advice and support
and to Syngenta and the EPSRC for financial support.
leave the diester
spectroscopic and analytical data identical to those reported previously: d
(400 MHz; CDCl
) 5.61 (2H, app. s, 3- and 4-H), 3.72 (6H, s, 2 Â OMe), 3.00 (4H,
app. s, 2- and 5-CH ).
7 a colourless oil which showed
(0.177 g, 82%)18 as
H
3
2
2
0. A sample of both treated and untreated reaction product was accurately
weighed and added to a volumetric flask. Each sample was digested overnight
in aqua regia (20 ml) and the resulting solution diluted to 100 ml with distilled
water. The solution was then analyzed by ICPMS, which had been standardized
using a ruthenium solution of known concentration. Each run was duplicated
References and notes
1
.
Handbook of Metathesis; Grubbs, R. H., Ed.; Wiley-VCH: Weinheim, Germany,
99
2
1
003; Vol. 1–3, Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003, 42, 1900–
923; Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592–4633;
as a check. Typical results were as follows: The total ruthenium content [ Ru
and 1 Ru] of an untreated sample according to ICPMS was 1542.8 ppb,
01
À1
Grubbs, R. H. Tetrahedron 2004, 60, 7117–7140.
equivalent to 1.5428 ppm or 1.5428
solution thus contained 154.28
l
g ml . The 100 ml total volume of
2
.
Welch, C. J.; Leonard, W. R.; Henderson, D. W.; Domer, B.; Childers, K. G.;
Chung, J. Y. L.; Harmer, F. W.; Albaneze-Walker, J.; Sajonz, P. Org. Process Res.
Dev. 2008, 12, 81–87.
lg
of Ru. The original untreated product
sample weighed 58.00 mg, which therefore contained 154.28
l
g of ruthenium,
À1
equivalent to 2660
lg g or 2660 ppm of ruthenium. A typical equivalent
figure for a treated sample weighing 74.00 mg was [Ru] = 0.984 ppb. This
equates to 0.0984
finally equates to 1.33
l
g in 100 ml of solution and hence in the 74 mg sample. This
À1
3.
4.
5.
Maynard, H. D.; Grubbs, R. H. Tetrahedron Lett. 1999, 40, 4137–4140.
Ahn, Y. M.; Yang, K.; Georg, G. I. Org. Lett. 2001, 3, 1411–1413.
Westhus, M.; Gonthier, E.; Brohm, D.; Breinbauer, R. Tetrahedron Lett. 2004, 45,
lg g or 1.33 ppm of ruthenium. The values quoted in
Table 1 are the average of two runs.
21. Keattch, C. J. GB Patent, 1963, 915,785; Chem. Abstr. 1963, 58, 43435.; Kitajima,
N.; Fukuzumi, S.; Ono, Y. J. Phys. Chem. 1978, 82, 1505–1509; Nawata, T.;
Sakaguchi, S.; Takeuchi, T. Jpn. Kokai Tokkyo Koho, JP 1987, 01097920; Chem.
Abstr. 1990, 112, 25719.; Rusek, J. J. J. Propul. Power 1996, 12, 574–579;
Venkatachalapathy, R.; Davila, G. P.; Prakash, J. Electrochem. Commun. 1999, 1,
614–617.
3
141–3142.
McEleney, K.; Allen, D. P.; Holliday, A. E.; Crudden, C. M. Org. Lett. 2006, 8,
663–2666. We suggest that this method can deliver ruthenium levels as low
6
.
.
2
as 35 ppm and that some calculations in this paper may be incorrect.
Cho, J. H.; Kim, B. M. Org. Lett. 2003, 5, 531–533.
7