[108-03-2]  · C3H7NO2  · 1-Nitropropane  · (MW 89.11)

(for aromatic aldehyde to nitrile conversion;2 nitronate, as acyl anion equivalent of n-propanal, as a n-propyl anion equivalent, reaction with electrophiles3)

Physical Data: mp -104 °C; bp 131 °C; d 1.001 g cm-3.

Solubility: 1.5 g wt % in H2O at 25 °C; sol ethanol, ether.

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

Handling, Storage, and Precautions: flammable; avoid contact with bases; toxic; dry nitronate salts can be explosive; 1-nitropropane (pKa = 8.98) can be deprotonated by bases such as NaOH, TEA, DBU, TMG, NaH, or LDA. The resulting 1-nitropropane nitronate is the usual reactive form of the reagent.

Conversion of Aromatic Aldehydes to Nitriles.

A one-step method for the conversion of aromatic and heterocyclic aldehydes to nitriles utilizes 1-nitropropane (as the source of hydroxylamine) and (NH3)2HPO4 as the reagents (eq 1).4

1,2-Addition to Carbonyl Compounds.

As a nucleophile, 1-nitropropane nitronate reacts with the carbonyl group of aldehydes and ketones (Henry reaction5); this is a method of chain extension by three carbon atoms (eq 2).6

The diastereoselectivity of the products obtained from the reaction with aldehydes is dependent upon the reaction conditions employed. The nitro aldol products have been used extensively in synthesis.

1,4-Addition to Carbonyl Compounds.

In the Michael reaction,7 1-nitropropane can serve as an n-propanoyl equivalent by a subsequent Nef reaction of the conjugate addition product (eq 3).8

Alternatively, 1-nitropropane can serve as an n-propyl anion equivalent in the Michael reaction by subsequent radical denitration of the conjugate addition product (eq 4).9

a,a-Doubly Deprotonated 1-Nitropropane.

C-Alkylation, C-acylation, and C-hydroxyalkylation products are obtained in good yields by the reaction of a,a-doubly deprotonated 1-nitropropane with alkyl halides, carboxylic acid derivatives, and aldehydes and ketones (Henry reaction). In the Henry reaction of the dianion with aldehydes, threo-enriched products are obtained. With ketones, better yields of the nitro aldol products are realized than under classical conditions (eq 5).10

Silyl Esters of aci-1-Nitropropane.

Nitropropane is converted to its O-t-butyldimethylsilyl ester, which is used as a reagent in the fluoride ion-catalyzed Henry reaction with aldehydes. The reaction gives good yields of products with a >95% erythro stereoselectivity (eq 6).11

1,3-Dipolar cycloaddition reactions of the silyl nitronates of 1-nitropropane with alkenes have been used to prepare 2-oxazolines, which can be transformed into a variety of nonheterocyclic compounds (eq 7).12

Propanenitrile Oxide Precursor.

The 1,3-dipolarophile propanenitrile oxide is prepared from 1-nitropropane for use in situ13 and can be used to synthesize heterocycles (eq 8).14

Related Reagents.

t-Butyldimethylsilyl Ethylnitronate; O,O-Dilithio-1-nitropropene; Nitroethane; Nitromethane.

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. Blatter, H. M.; Lukaszewski, H.; de Stevens, G. JACS 1961, 83, 2203.
3. (a) Seebach, D.; Colvin, E. W.; Lehr, F.; Weller, T. C 1979, 33, 1. (b) Rosini, G.; Ballini, R. S 1988, 833.
4. Blatter, H. M.; Lukaszewski, H.; de Stevens, G. OS 1963, 43, 58.
5. Rosini, G. COS 1991, 2, Chapter 1.10.
6. Rosini, G.; Ballini, R.; Sorrenti, P. S 1983, 1014.
7. Jung, M. E. COS 1991, 4, Chapter 1.1.
8. Ballini, R.; Petrini, M.; Marcantoni, E.; Rosini, G. S 1988, 231.
9. Ono, N.; Kamimura, A.; Miyake, H.; Hamamoto, I.; Kaji. A. JOC 1985, 50, 3692.
10. Seebach, D.; Lehr, F. AG(E) 1976, 15, 505.
11. Seebach, D.; Beck, A. K.; Mukhopadhyay, T.; Thomas, E. HCA 1982, 65, 1101.
12. (a) Torssell, K.; Zeuthen, O. ACS 1978, B32, 118. (b) Andersen, S. H.; Das, N. B.; Jorgensen, R. D.; Kjeldsen, G.; Knudsen, J. S.; Sharma, S. C.; Torssell, K. B. G. ACS 1982, B36, 1.
13. Mukaiyama, T.; Hoshino, T. JACS 1960, 82, 5339.
14. McMurry, J. C. OS 1973, 53, 59.

Walter W. Zajac, Jr.

Villanova University, PA, USA

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