Pyridyne in chemistry is the pyridine analogue of benzyne. Pyridynes are the class of reactive intermediates derived from pyridine. Two isomers exist, the 2,3-pyridine (2,3-didehydropyridine) and the 3,4-pyridyne (3,4-didehydropyridine). The reaction of 3-bromo-4-chloropyridine with furan and lithium amalgam gives 1,4-epoxy-dihydroquinoline through the 2,3-pyridyne intermediate. The reaction of 4-bromopyridine with sodium in liquid ammonia gives both 3-aminopyridine and 4-aminopyridine through the 3,4-pyridyne intermediate and an E1cB-elimination reaction.
History
Pyridynes were first postulated by Levine and Leake in 1955. In 1969 Zoltewicz and Nisi trapped 3,4-pyridyne in a reaction of 3-bromopyridine with methylmercaptan and sodium amide in ammonia. The methylthio and amino pyridines were found to be formed in the same ratio.
In 1972 Kramer and Berry inferred the formation of 3,4-pyridyne in gas-phase photolysis of pyridine-3-diazonium-4-carboxylate via time-of-flight mass spectrometry. The dimer compound diazabiphenylene was detected. In 1988 Nam and Leroy reported the matrix isolation (13K, Ar) of 3,4-pyridyne by photolysis of 3,4-pyridinedicarboxylic anhydride with the IR-spectrum revealing an acetylenic bond in the same way as ortho-benzyne.
Scope
Strategies involving pyridynes have been employed in the total syntheses of ellipticine and (S)-Macrostomine.
References
- Handbook of Heterocyclic Chemistry, (2010) y, Alan R. Katritzky,Christopher A. Ramsden,J. Joule,Viktor V. Zhdankin
- Heterocyclic Chemistry, (2001) Malcolm Sainsbury
- Levine, R.; Leake, W. W. (1955). "Rearrangement in the Reaction of 3-Bromopyridine with Sodium Amide and Sodioacetophenone". Science. 121 (3152): 780. Bibcode:1955Sci...121..780L. doi:10.1126/science.121.3152.780. PMID 17773207.
- Zoltewicz, John A.; Nisi, Carlo (1969). "Trapping of 3,4-Pyridyne by Thiomethoxide Ion in Ammonia". The Journal of Organic Chemistry. 34 (3): 765–766. doi:10.1021/jo01255a072.
- Kramer, Jerry; Berry, R. Stephen (1972). "Gaseous 3,4-Pyridyne and the Formation of Diazabiphenylene". Journal of the American Chemical Society. 94 (24): 8336–8347. doi:10.1021/ja00779a010.
- Synthesis and Diels-Alder reactions of 1,3-dimethyl-4-(phenylsulfonyl)-4H-furoindole. A new annulation strategy for the construction of ellipticine and isoellipticine Gordon W. Gribble, Mark G. Saulnier, Mukund P. Sibi, and Judy A. Obaza-Nutaitis The Journal of Organic Chemistry 1984 49 (23), 4518-4523 doi:10.1021/jo00197a039
- Total syntheses of ellipticine alkaloids and their amino analogues Original Research Article Tetrahedron, Volume 48, Issue 48, 27 November 1992, Pages 10645-10654 Chin-Kang Sha, Jeng-Fenn Yang doi:10.1016/S0040-4020(01)88360-5
- A Five-Step Synthesis of (S)-Macrostomine from (S)-Nicotine Monica F. Enamorado, Pauline W. Ondachi, and Daniel L. Comins Organic Letters 2010 12 (20), 4513-4515 doi:10.1021/ol101887b