[4749-28-4]  · C3H5NO2  · 2-Nitro-1-propene  · (MW 87.09)

(Michael addition to afford 1,4-diketones,4 furans,7 and pyrroles,11 and an electrophilic reagent for a-keto cation in the Friedel-Crafts reaction12)

Physical Data: bp 56-57 °C/86 mmHg, 50 °C/60 mmHg; n20D 1.4348, d20 1.0492 g cm-3.

Solubility: sol Et2O, THF, acetone, CH2Cl2.

Preparative Methods: by dehydration of 2-nitro-1-propanol (ca. 98% purity commercially or prepared from Nitroethane and formalin, yield 70%2) with phthalic anhydride (73%)3 or Acetic Anhydride-AcONa (85%).4

Handling, Storage, and Precautions: pure 2-nitro-1-propene may be stored in a freezer for several weeks; best prepared immediately before use since it tends to polymerize; this reagent is a powerful lachrymator. Use in a fume hood.

Michael Acceptor.

This reagent readily undergoes addition reactions with many different nucleophiles to give saturated nitro compounds,5 which are readily converted into a variety of compounds such as amines or ketones via reduction or the Nef reaction, respectively (eq 1).1

Lewis acid-promoted addition of silyl enol ethers to this reagent provides a very useful method for the preparation of 1,4-diketones (eq 2).4 The 1,4-diketones thus obtained are converted into cyclopentenones in high yields.5

Carboxylic acid dianions or ester enolates react with this reagent to give g-keto acids after hydrolysis (eq 3). However, a low temperature is required to suppress the polymerization of the nitroalkene.6

The base-catalyzed addition of 1,3-diketones to 2-nitropropene followed by heating the initial Michael adducts results in the formation of furans. Thus dimedone and acetylacetone react with 2-nitropropene to give the furans shown in eqs 4 and 5.7

The reaction of this reagent with ketone enolates followed by treatment with Acetic Anhydride gives acetic nitronic anhydrides, which are converted into 1,4-diketones or pyrroles (eq 6).8

The conjugate addition of sulfonyl carbanions to 2-nitropropene, followed by ozonolysis or acid treatment of the resulting nitronates (Nef reaction9) and subsequent elimination of sulfinic acid from b-ketosulfones with 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU), gives a,b-unsaturated ketones (eq 7).10

A unique pyrrole synthesis is realized by the reaction of nitroalkenes with isocyanoacetates. For example, 2-nitropropene condenses with methyl isocyanoacetate in the presence of DBU to produce the pyrrole which is a trail marker pheromone (eq 8).11

Friedel-Crafts-Type Reactions.

A novel electrophilic reagent is formed by diprotonation of nitroalkenes in Trifluoromethanesulfonic Acid. O,O-Diprotonated 2-nitropropene undergoes two alternative electrophilic reactions with benzene which yields a-phenylacetone12 or 4H-1,2-benzoxazine,13 depending on the reaction conditions. These products are not readily synthesized by the conventional Friedel-Crafts reaction. Benzoxazine acts as a precursor of o-benzoquinone methide (eq 9).14

Diels-Alder Reaction.

This reagent is an excellent dienophile in the Diels-Alder reaction and it reacts with various dienes.15 The regiochemistry of the Diels-Alder reaction is effectively controlled by the nitro group.16

Related Reagents.

Nitroethylene; 1-Nitro-1-propene.

1. (a) Schickh, O.; Padeken, H. G.; Segnitz, A. MOC 1971, 10, pp 9-462. (b) Bauer, H. H.; Urbas, L. The Chemistry of the Nitro and Nitroso Group; Feuer, H., Ed.; Interscience: New York, 1970; Part 2. (c) Yoshikoshi, A.; Miyashita, A. ACR 1985, 18, 284.
2. Feuer, H.; Miller, R. JOC 1961, 26, 1348.
3. Miyashita, M.; Yanami, T.; Yoshikoshi, A. OSC 1990, 7, 396.
4. Hass, H. B.; Susie, A. G.; Heider, R. L. JOC 1950, 15, 8.
5. (a) Miyashita, M.; Yanami, T.; Yoshikoshi, A. JACS 1976, 98, 4679. (b) Miyashita, M.; Yanami, T.; Yoshikoshi, A. OSC 1990, 7, 414.
6. Miyashita, M.; Yamaguchi, R.; Yoshikoshi, A. JOC 1984, 49, 2857.
7. Yanami, T.; Ballatore, A.; Miyashita, M.; Kato, M.; Yoshikoshi, A. JCS(P1) 1978, 1144.
8. Miyashita, M.; Awen, B. Z. E.; Yoshikoshi, A. T 1990, 46, 7569.
9. Pinnick, H. W. OR 1990, 38, 655.
10. Awen, B. Z.; Miyashita, M.; Shiratani, T.; Yoshikoshi, A.; Irie, H. CL 1992, 767.
11. Barton, D. H. R.; Kervagoret, J.; Zard, S. Z. T 1990, 46, 7587.
12. Okabe, K.; Ohwada, T.; Ohta, T.; Shudo, K. JOC 1989, 54, 733.
13. Ohwada, T.; Okabe, K.; Ohta, T.; Shudo, K. T 1990, 46, 7539.
14. Yato, M.; Ohwada, T.; Shudo, K. JACS 1990, 112, 5341.
15. Noland, W. E.; Bambury, R. S. JACS 1955, 77, 6386.
16. Ono, N.; Miyake, H.; Kamimura, A.; Kaji, A. JCS(P1) 1987, 1929. Noboru OnoEhime University, Matsuyama, Japan

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