4510 J . Org. Chem., Vol. 64, No. 12, 1999
Notes
Ta ble 1. Con ver sion of Olefin s in to r-Nitr o Keton es w ith Me3SiONO2-Cr O3 or Me3SiONO2-DMSO Rea gen t System s
Me3SiONO2/CrO3 Me3SiONO2/DMSO
entry
olefin
R-nitro ketone
yield (%)
time (h)
yield (%)
time (h)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
cyclopentene
cyclohexene
cycloheptene
cyclooctene
cyclododecene
1-hexene
1-octene
2-octene
1-dodecene
1-tridecene
2-nitrocyclopentanone24a
27
61
70
65
72
88
70
60b
94
81
76
76c
24
24
24
24
24
24
24
24
20
20
10
10
a
3
3
6
5
2-nitrocyclohexanone24b
70
73
45
64
68
52
2-nitrocycloheptanone24b
2-nitrocyclooctanone24a
2-nitrocyclododeca-none24b
1-nitro-2-hexanone24c
6
1-nitro-2-octanone24d
10a
a
2-nitro-3-octanone24e + 3-nitro-2-octanone
1-nitro-2-dodecanone24f
65
72
6
8
a
a
a
a
1-nitro-2-tridecanone
R-methylstyrene
trans-stilbene
1,2-dimethylstyrene
1,5-cyclooctadiene
R-nitro-2-phenyl-2-ethanone7b
1-nitro-1,2-diphenyl-2-ethanone24g
acetophenone + nitroethane
45
2
a
No reaction occurred. b 1:1 ratio of the two nitro ketones was formed that could not be separated. c A small amount (7%) of benzaldehyde
was formed in this reaction.
species NO2OCrO2SiMe3, which can function both as a
source of +NO2 as well as the oxidant -OCrO2OSiMe3.
When olefins are reacted with this species, intermedi-
ate 2 (Y ) CrO2OSiMe3, Scheme 1) should form, eventu-
ally to result in the corresponding R-nitro ketone. It is,
however, possible that the intermediate 2 forms via a
The success of this reagent system led us to explore
the use of DMSO as an oxidant. It was expected that a
Kornblum-type19b intermediate 2 (Y ) +SMe2) should
form, which under basic conditions would give an R-nitro
ketone. Thus, the reagent system Me3SiONO2-DMSO
readily reacted with several olefins (Table 1) to give the
corresponding R-nitro ketones in fair yields (45-73%).
Unfortunately there was no reaction with cyclopentene,
2-octene, â-methylstyrene, stilbene, 1,2-dimethylstyrene,
and 1,5-cyclooctadiene possibly due to lower nucleophi-
licity of DMSO (Table 1). On the other hand, regioselec-
tivity was similar to that found with the Me3SiONO2-
CrO3 reagent. These results clearly indicate that these
new reagent systems are excellent in situ sources of +NO2
associated with chromium- and sulfur-based oxidants.
They are convenient to handle and are useful for both
cyclic as well as acyclic olefins. We anticipate that these
reagent systems will find application26 in organic syn-
thesis.
radical pathway,21 akin to N2O4 or NO2Cl23 addition to
22
olefins.
In practice, a variety of cyclic disubstituted as well as
acyclic mono- and disubstituted olefins react with this
reagent system to yield R-nitro ketones in good to
excellent yields (Table 1). Among cyclic olefins, cyclopen-
tene gave a relatively poor yield (27%) of R-nitrocyclopenta-
none.24a The reaction exhibits remarkable Markovnikov-
like regioselectivity with terminal olefins, giving the
R-nitro ketones exclusively (entries 6, 7, 9, and 10).
Unfortunately, the reaction leads to C-C bond cleavage
with trisubstituted olefins25 (entry 13), and with unsym-
metrical internal olefins no regioselectivity is observed
(entry 8). It is, therefore, clear that the reaction is most
suitable for terminal olefins and symmetric cyclic olefins
unsubstituted at the double bond.
To further explore the scope of these reagent systems,
we reacted them with olefinic acetals 3 and 4 (eq 1).27
(19) (a) This intermediate 2 (Y ) +SMe2) is similar to the one
obtained in Moffat oxidation (see: Pftitzner, K. E.; Moffatt, J . G. J .
Am. Chem. Soc. 1965, 87, 5661. Moffatt, J . G. In Oxidation; Augustine,
R. L., Trecker, D. J ., Eds.; Marcell Dekker: New York, 1971; Vol. 2, p
12) or Swern oxidation (Mancuso, A. J .; Huang, S.-L.; Swern, D. J .
Org. Chem. 1978, 43, 2480) of alcohols. (b) Replacement of a halide,
tosylate, or mesylate by DMSO was originally reported by Kornblum
involving similar intermediates. See: Kornblum, N.; J ones, W. J .;
Anderson, G. J . J . Am. Chem. Soc. 1959, 81, 4113.
(20) Kimura, M.; Kajita, K.; Onoda, N.; Morosawa, S. J . Org. Chem.
1990, 55, 4887.
(21) We thank one of the reviewers for pointing out the possibility
of radical reactions.
(22) Shechter, H.; Conrad, F.; Daulton, A. I.; Kaplin, R. E. J . Am.
Chem. Soc. 1952, 74, 3052.
(23) Hassner, A.; Kropp, J . E.; Kent, J . E. J . Org. Chem. 1969, 34,
2628.
Neither of these compounds gave a clean product, though
the IR spectra of the crude reaction mixtures indicated
a lactone group instead of the expected NO2 group. This
led us to explore the possibility of converting cyclic ethers
(24) (a) It is known in the literature (see: Feuer, H.; Pivawer, P.
M. J . Org. Chem. 1966, 31, 3152 and ref 11 above) that R-nitrocyclo-
pentanone is prone to undergo ring cleavage, and hence, it is not
surprising that in the present study we have a low yield of this
compound. (b) Bischoff, C.; Schroden, E. J . Prakt. Chem. 1972, 314,
891. (c) Shvedov, V. I.; Altukhova, L. B.; Ermakov, Yu. I. U.S.S.R.
398,104 (C1. C07C); Chem. Abstr. 1976, 84, 17980f. (d) Lachowickz,
D. R.; Kreuz, K. L. Am. Chem. Soc., Div. Petrol. Chem., preprints 1967,
12, 85; Chem. Abstr. 1967, 67, 43367a. (e) Ono, N.; Miyake, H.; Fuji,
M.; Kaji, A. Tetrahedron Lett. 1983, 24, 3477. (f) Simmons, T.; Kreuz,
K. L. J . Org. Chem. 1968, 33, 836. (g) Saito, I.; Takami, M.; Konoike,
T.; Matsuuro, T. Bull. Chem. Soc. J pn. 1973, 46, 3198.
(25) Other trisubstituted olefins such as limonene, R-pinene, and
∆3-carene gave a complex mixture of products.
(26) Langlois et al. (see: Chassaing, C.; Haudrechy, A.; Langlois,
Y. Synth. Commun. 1997, 27, 61) have made use of the Me3SiONO2-
CrO3 reagent system in their studies related to the synthesis of
Huperzine A, a Lycopodium alkaloid.
(27) Vankar, Y. D.; Bawa, A.; Kumaravel, G. Tetrahedron 1991, 47,
2027. Vankar, Y. D.; Chaudhuri, N. C. Synth. Commun. 1991, 21, 885.
(28) (a) Sasidharan, M.; Suresh, S.; Sudalai A. Tetrahedron Lett.
1995, 36, 9071 and references therein. (b) Smith, A. B.; Scarborough,
R. M., J r. Synth. Commun. 1980, 10, 205. (c) Booker-Milburn, K. I.;
Cowell, J . K. Tetrahedron Lett. 1996, 37, 2177. (d) Hobbs, P. D.;
Magnus, P. D. J . Am. Chem. Soc. 1976, 98, 4594. (e) Shiori, T.;
Ninomiya, K.; Martin, V. S.; Sharpless, K. B. J . Org. Chem. 1981, 46,
3936.