Thallium in Organic Synthesis

Several excellent review articles appeared in the early 1970s [3 a, 4] and in the 1980s [5] in which all the fundamental and characteristic reactions using H salts were included. A recent review by Ferraz et al. [6] thoroughly summarized results from use of Tl(Ill) in organic synthesis from 1989 to 1998. 

This short article deals mainly with typical synthetically useful and important organic transformations using Tl(III) and T1(I) salts, e.g. commercial l1(()Ac) j, T1(OCOCF3)3, T1(NO3)3 3H2O (abbreviated as TTA, TTFA, and TTN, respectively), TlOEt and TlOH and some Tl(III) species generated in situ. Because the examples cited here were selected arbitrarily, readers should consult the reviews mentioned above for more detailed and thorough chemistry. 

Main Group Metals in Organic Synthesis. Edited by H. Yamamoto, K. 0 hima Copyright 2 04 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-30508-4 

---

McKillop, A., Bromley, D. Thallium in organic synthesis. VIII. Preparation of aromatic bromides. Tetrahedron Lett. 1969, 1623-1626. 

I 9 Thallium in Organic Synthesis catalytic cycle for Scheme 9.72... 

The nonoxidative applications of thallium in organic synthesis are relatively few. Organothallium reagents act as mild nucleophiles. Thus, acid chlorides can be alkylated by R3TI, as can a-haloethers. Nucleophilicity is greater for R4TD. Alkyltrimethylthallate(III) is prepared from MesTl and RLi, and may be used to alkylate a,/ -unsaturated ketones. ... 

It would be instructive to apply electron spin resonance spectroscopy in these various metal cation oxidations. Certainly the homogeneous nature of these reactions offers greater possibilities to the kineticist than is afforded by the heterogeneous nature of the metal-catalysed eliminations. Considering the recent discoveries of the synthetic utility of thallium in organic synthesis " , thallous salts might prove to be extremely useful catalysts for dehalogenations. as under the reaction conditions the less stable olefins are rapidly isomerised. 

E. C. Taylor, A. McKillop, and coworkers. Thallium in organic synthesis 49. Oxidative rearrangement of chalcone dimethylketals to methyl-2,3-diaryl-3-methoxypropanoates with thallium(m) trinitrate in trimethylorthoformate. J. Org. Chem., 1977, 42, 4167 50. A convenient synthesis of thallium(i) cyanide, a useful reagent in organic synthesis (for conversion of aroyl chlorides to aromatic a-ketonitriles). J. Org. Chem., 1978, 43, 2280 51. Oxidation of enolizable ketones to a-nitratoketones by thallium(in) nitrate in acetonitrile. 

McKillop A, Taylor EC. Compounds of thallium in organic synthesis. In Wilkinson G, editor. Comprehensive organo-metallic chemistry. Vol. 7. New York Pergamon Press Ltd. 1982 p 465-513. 

McKillop A, Hunt JD, Kienzle F, Bigham E, Taylor EC. Thallium in organic synthesis. 32. Oxidative rearrangement of olefins using thallium(III) nitrate (TTN). J. Am. Chem. Soc. 1973 95 3635-3640. 

Taylor, E.C., Altland, H.W., Kienzle, F., and McKillop, A., Thallium in organic synthesis. XLl. Synthesis of 1-substituted 2(lH)-pyridones. New synthesis of unsymmetrical biphenyls via photochemical nitrogen-oxygen bond cleavage of l-aroyloxy-2(liJ)-pyridones, /. Org. Chem., 41, 24-27, 1976. 

---