2-Nitropropane1

[79-46-9]  · C3H7NO2  · 2-Nitropropane  · (MW 89.11)

(as nitronate, oxidant for allyl and benzyl halides;2 acyl anion equivalent of acetone, reacts with electrophiles;3 reactant in electron-transfer reactions;4 isopropylidene equivalent in cyclopropanations5)

Physical Data: mp -91 °C; bp 120 °C; d 0.988 g cm-3.

Solubility: 1.7 g wt % in H2O at 25 °C; sol ethanol and ether at 20 °C.

Form Supplied in: liquid; widely available. Drying: use calcium chloride, calcium sulfate, or magnesium sulfate.

Handling, Storage, and Precautions: flammable; avoid contact with base; cancer suspect agent; dry nitronate salts can be explosive; bases such as NaOH, TEA, DBU, TMG, NaH, or LDA can be used to deprotonate 2-nitropropane (pKa = 7.67) to give the ambident nucleophile 2-nitropropane nitronate, which is the reactive form of the reagent. Use in a fume hood.

Oxidizing Agent.

Primary benzylic halides,2 including heterocyclic halides,6 are converted to aldehydes by means of 2-nitropropane-Sodium Ethoxide (eq 1).

Secondary benzylic halides are not oxidized, but secondary allyl halides are oxidized regioselectively and stereoselectively to a,b-unsaturated aldehydes with sodium 2-nitropropane nitronate in the presence of Tetrakis(triphenylphosphine)palladium(0) (eq 2).7

C-Allylation.

Unlike secondary allyl halides, which alkylate the oxygen atoms of the nitronate of 2-nitropropane, primary allyl alcohols, acetates, and phenyl ethers alkylate the carbon atom, leading to C-allylated 2-nitropropanes (eq 3).8 Dichlorobis(triphenylphosphine)palladium(II) with 2 additional equiv of Triphenylphosphine is used as catalyst.

C-Alkylation.

A variety of alkylating reagents, including o- and p-nitrobenzyl chlorides,3 N-substituted pyridinium salts,9 hypervalent iodofluoroalkanes,10 and organomercury compounds,11 can be used to alkylate the potassium salt of 2-nitropropane (eq 4).

Conjugate Addition.

The nitronate salt of 2-nitropropane adds to electron-deficient alkenes (Michael reaction) and with subsequent radical denitration serves as an isopropyl anion equivalent (eq 5).12

Synthesis of 1,1-Dimethylethylenes.

The nitronate salt of 2-nitropropane reacts with geminal dinitroalkanes, resulting in vicinal dinitroalkanes13a which can be converted to tetrasubstituted alkenes by reduction (eq 6).13b

Synthesis of Substituted gem-Dimethylcyclopropanes.

The sodium or potassium salts of 2-nitropropane can be used as isopropylidene-transfer reagents. In a one-pot, tandem Michael addition-nitrite displacement sequence of reactions, electron-deficient alkenes react with the nitronate salt of 2-nitropropane to give gem-dimethylcyclopropanes in good yields (eq 7).5 The reaction appears to be stereoselective with the various substrates that have been used.5

C-C Coupling at b-Carbon.

The a,b-doubly deprotonated 2-nitropropane can be benzylated, benzoylated, and hydroxybenzylated at the b-carbon in modest yields (eq 8).14

Related Reagents.

O,O-Dilithio-1-nitropropene; 1-Nitropropane.


1. (a) Torssell, K. B. G. Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis; VCH: New York, 1988. (b) The Chemistry of the Nitro and Nitroso Groups, Part 2; Feuer, H., Ed.; Interscience: New York, 1970. (c) The Chemistry of Amino, Nitroso, and Nitro Compounds and Their Derivatives; Patai, S., Ed.; Wiley: Chichester, 1982. (d) Nitroparaffins, TDS1; Angus Chemical Co.: Northbrook IL, 1989. (e) Nitro Compounds: Recent Advances in Synthesis and Chemistry; Feuer, H; Nielsen, A. T., Eds.; VCH: New York, 1990.
2. Kilenyi, S. N. COS 1991, 7, Chapter 4.4.
3. Rosini, G.; Ballini, R. S 1988, 833.
4. Kornblum, N. Aldrichim. Acta 1990, 23, 71.
5. (a) Ono, N.; Yanai, T.; Hamamoto, I.; Kamimura, A.; Kaji, A. JOC 1985, 50, 2806. (b) Babler, J. H.; Spina, K. P. TL 1985, 26, 1923.
6. Meerpoel, L.; Deroover, G.; Van Aken, K.; Lux, G.; Hoornaert, G. S 1991, 765.
7. Suzuki, S.; Onishi, T.; Fujita, Y.; Otera, J. SC 1985, 15, 1123.
8. Aleksandrowicz, P.; Piotrowska, H.; Sas, W. T 1982, 38, 1321.
9. Katritzky, A. R.; De Ville, G.; Patel, R. C. T 1981, 37, Suppl. 1, 25.
10. Umemoto, T.; Kuriu, Y. TL 1981, 22, 5197.
11. Martin, O. R.; Xie, F.; Kakarla, R.; Benhamza, R. SL 1993, 165.
12. Ono, N.; Kamimura, A.; Miyake, H.; Hamamoto, I.; Kaji, A. JOC 1985, 50, 3692.
13. (a) Kornblum, N.; Boyd, S. D.; Pinnick, H. W.; Smith, R. G. JACS 1971, 93, 4316. (b) Kornblum, N.; Cheng, J. JOC 1977, 42, 2944.
14. Henning, R.; Lehr, F.; Seebach, D. HCA 1976, 59, 2213.

Walter W. Zajac, Jr.

Villanova University, PA, USA



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