Propanediol led to a crystalline compound that was unam-
biguously proven to be the sulfonimidate by X-ray diffraction
Table 2. Preparation of Sulfonimidates with 3 Equiv of
Alcohol
(entry 8). The ethyl compound was also prepared according
to the Roy method; both reactions gave the same product.
As stated before, the only observed byproducts were sul-
fonamides. Lowering the amount of alcohol below 3 equiv
leads to an increase of oxidation at the expense of the desired
product. This result is still interesting, since to the best of
our knowledge no such oxidation involving iodine (III)
derivatives has been reported in the literature. Finally, we
were pleased to see that our reaction was not limited to
primary sulfinamides. The N-butyl sulfonimidate is then
produced in fair yield (entry 12; when the solvent was
methanol, sulfonimidate was obtained in 74% yield), while
aromatic alcohols are not suitable: degradation occurs
presumably through electrophilic aromatic substitution (entry
entry
1
2
3a
R
R′
2 (%)
4 (%)
Me
Et
i-Pr
allyl
H
85
67
39
60
76
71
57
60
95
62
-
5
23
30
36
21
13
27
1
H
H
H
H
H
H
H
H
H
H
Bu
4
5a
6a
7
HCtCCH2
CH2dCH-(CH2)2
Ph-(CH2)4
HO-(CH2)3
HO-(CH2)5
Br-(CH2)2
Ph
8
9
3
11
-
1
1).
In conclusion, we have devised an efficient one-pot
1
1
1
0
1b
2
Me
52
22
procedure to prepare sulfonimidates in good to excellent
yields, where the reported methods required two steps. We
also observed a dramatic difference in reactivity between
sulfinamides and sulfonamides toward iodosobenzene, which
a
MS 3 Å was also used. b Immediate degradation was observed.
a
can be rationalized by a strong pK difference. In addition,
The main limitation was, of course, the amount of alcohol
needed for the transformation. While this posed no problem
when methanol or ethanol were used, it became more
troublesome when a more expensive alcohol was targeted.
We reasoned that if the limiting step was the solvolysis of
the starting material, then we should be able to reduce the
equivalents of alcohol used, ideally lowering it to two.
Therefore we switched to acetonitrile, anticipating that its
polarity could allow the formation of the dialkoxy adducts.
Indeed we observed the formation of the desired sulfonimi-
dates, albeit in slightly lower yields. Sulfonamidesarising
from the standard oxidation of sulfinamidesswas also
isolated, and this accounts for the loss in yield. The results
are given in Table 2.
The reaction was smooth except in the case of secondary
alcohols (entry 3), which led to a dramatic drop in yield of
the desired product. We imagined that the water released
during the formation of the dialkoxyiodosobenzene was
accountable for this loss, but the addition of molecular sieves
in the reaction mixture was not entirely conclusive. It may
sometimes slightly improve yields, but not as a general rule.
Nonetheless, the result was quite satisfactory for expensive
primary alcohols or for those whose physical properties
would not allow them to be used as solvents (e.g. entry 7).
sulfonimidates can rearrange to sulfonamides.16 We are
currently looking for conditions that could trigger this
rearrangement in the same pot, leading to a one-pot alterna-
tive to the Mitsunobu reaction. These results, as well as the
asymmetric version of our reaction, will be reported in due
1
7
course.
Acknowledgment. This work was supported by the
CNRS and Minist e` re de la Recherche. D.L. thanks the
Minist e` re de la Recherche for a grant (AMX). The authors
thank Dr. J. Vaisserman (UPMC) for the X-ray analysis.
Supporting Information Available: Detailed procedure
and full characterization of all new sulfonimidates (including
copies of their NMR spectra); crystal structure of the
sulfonimidate derived from propanediol. This material is
available free of charge via the Internet at http://pubs.acs.org.
OL026837B
(
11) Davis, F. A.; Zhou, P.; Reddy, G. V. J. Org. Chem. 1994, 59, 3243-
3
245.
(
12) Stang, P. J.; Zhdankin, V. V. Chem. ReV. 1996, 96, 1123-1178.
(13) (a) Abramovitch, R. A.; Bailey, T. D.; Takaya, T.; Uma, V. J. Org.
Chem. 1974, 39, 340-345. (b) Mansuy, D.; Mahy, J. P.; Dur e´ ault, A.; Bedi,
G.; Battioni, P. J. Chem. Soc., Chem. Commun. 1984, 1161-1163.
(
14) Schardt, B. C.; Hill, C. L. Inorg. Chem. 1983, 22, 1563-1565.
(
7) (a) Johnson, C. R.; Jonsson, E. U.; Bacon, C. C. J. Org. Chem. 1979,
(15) To our knowledge, the pKa values of the two intermediates have
not been measured, but there is usually a four-unit gap between sulfonyl
and sulfinyl derivatives.
4
4
4, 2055-2061. (b) Johnson, C. R.; Wambsgans, A. J. Org. Chem. 1979,
4, 2278-2280.
(8) Johnson, C. R.; Jonsson, E. U.; Wambsgans, A. J. Org. Chem. 1979,
(16) Challis, B. C.; Iley, J. N. J. Chem. Soc., Perkin Trans. 2 1985, 699-
703.
(17) Our initial experiments show that chirality on the sulfur is destroyed
during the reaction. Enantiopure sulfinamides lead to racemic sulfonimidates.
Transfer of chirality from auxiliaries on nitrogen is under study.
4
4, 2061-2065.
(
9) Roy, A. K. J. Am. Chem. Soc. 1993, 115, 2598-2603.
(10) Maricich, T. J.; Jourdenais, R. A.; Albright, T. A. J. Am. Chem.
Soc. 1973, 95, 5831-5832.
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