24. Barton-Zard Reaction
D. H. R. Barton et al., Tetrahedron 46, 7587 (1990).
Formation of a pyrrole by condensation of a substituted nitroso-alkene with an isocyanoester:
Synthetic applications: T. D. Lash et al., Tetrahedron Letters 35, 2493 (1994); idem. et al., ibid. 38, 2031 (1997); E. T. Pelkey et al., Chem. Commun. 1996, 1909.
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23. Barton Reaction
D. H. R. Barton et al., J. Am. Chem. Soc. 82, 2640 (1960); 83, 4076 (1961).
Conversion of a nitrite ester to a γ-oximino alcohol by photolysis involving the homolytic cleavage of a nitrogen-oxygen bond followed by hydrogen abstraction:
M. Akhtar, Advan. Photochem. 2, 263 (1964); R. H. Hesse, Advan. Free Radical Chem. 3, 83 (1969); J. Kalvoda, Angew. Chem. Int. Ed. 8, 525 (1964). Mechanism: D. H. R. Barton et al., J. Chem. Soc. Perkin Trans. I 1979, 1159. Synthetic application: A. Herzog et al., Angew. Chem. Int. Ed. 37, 1552 (1998).
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22. Barton Olefin Synthesis (Barton-Kellogg Reaction)
D. H. R. Barton et al., Chem. Commun. 1970, 1226; R. M. Kellogg, S. Wassenaar, Tetrahedron Letters 1970, 1987; R. M. Kellogg et al., ibid. 4689.
Olefin synthesis by two-fold extrusion of nitrogen and sulfur from a ∆3-1,3,4-thiadiazoline intermediate. Particularly applicable to the synthesis of moderately hindered tetra-substituted ethylenes:
Scope and limitations: D. H. R. Barton et al., J. Chem. Soc. Perkin Trans. I 1974, 1794. Synthetic applications: A. P. Schaap, G. R. Faler, J. Org. Chem. 38, 3061 (1973); L. K. Bee et al., ibid. 40, 2212 (1975); M. D. Bachi et al., Tetrahedron Letters 1978, 4167; J. E. McMurry et al., J. Am. Chem. Soc. 106, 5018 (1984); F. J. Hoogesteger et al., J. Org. Chem. 60, 4375 (1995). Cf. McMurry Reaction.
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21. Barton Deoxygenation (Barton-McCombie Reaction) D. H. R. Barton, S. W. McCombie, Perkin Trans. I 1975, 1574.
Deoxygenation of alcohols via their thiocarbonyl derivatives which undergo free radical scission upon treatment with tri-n-butyltin hydride:
Mechanistic study: J. E. Forbes, S. Z. Zard, Tetrahedron Letters 30, 4367 (1989). Review: M. Pereyre et al., Tin in Organic Synthesis (Butterworths, Boston, 1987) pp 84-96. Review of methodological improvements, particularly the replacement of tri-n-butyltin hydride with silicon hydrides: C. Chatgilialoglu, C. Ferreri, Res. Chem. Intermed. 19, 755-775 (1993).
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20. Barton Decarboxylation
D. H. R. Barton et al., Chem. Commun. 1983, 939; eidem, Tetrahedron 41, 3901 (1985).
Radical decarboxylation of organic acids to the corresponding noralkane with tri-n-butyltin hydride or t-butylmercaptan:
Synthetic application: F. E. Ziegler, M. Belema, J. Org. Chem. 62, 1083 (1997).
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17. Barbier(-type) Reaction
P. Barbier, C. R. Acad. Sci. 128, 110 (1899).
One-step procedure for the preparation of alcohols from organic halides and aldehydes or ketones:
Review of mechanistic studies of Sm-mediated coupling: D. P. Curran et al., Synlett 1992, 943-961. Book: C. Blomberg, The Barbier Reaction and Related One-Step Processes, K. Hafner et al., Eds. (Springer-Verlag, New York, 1993) 183 pp. Zn-promoted coupling: F. Hong et al., Chem. Commun. 1994, 289. Sm-mediated coupling: M. Kunishima et al., Chem. Pharm. Bull. 42, 2190 (1994). Comparison with Ni(0) insertion chemistry for intramolecular cyclization: M. Kihara et al., Tetrahedron 48, 67 (1992). Cf. Grignard Reaction.
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16. Bamford-Stevens Reaction; Shapiro Reaction W. R. Bamford, T. S. Stevens, J. Chem. Soc. 1952, 4735.
Formation of olefins by base-promoted decomposition of p-toluenesulfonylhydrazones of aldehydes and ketones:
The formation of unrearranged alkenes, generally the less substituted isomers, by treatment of ketone derived p-toluenesulfonylhydrazones with alkyl lithium reagents is known as the Shapiro reaction: R. H. Shapiro, M. J. Heath, J. Am. Chem. Soc. 89, 5734 (1967). Use of N,N-diethylaminosulfonylhydrazones: J. Kang et al., Bull. Korean Chem. 13, 192 (1992).
Silicon directing effect: T. K. Sarkar, B. K. Ghorai, Chem. Commun. 1992, 1184. Reviews: R. H. Shapiro, Org. React. 23, 405-507 (1976); R. M. Adlington, A. G. M. Barrett, Accts. Chem. Res. 16, 55-59 (1983); K. Maruka, H. Yamamoto, Comp. Org. Syn. 6, 776-779 (1991); A. R. Chamberlin, D. J. Sall, ibid. 8, 944-949.
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