Kharasch Addition

01 February, 2014 / by webmaster / in Reactions

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Kharasch addition is the addition of polyhalogenated compounds to alkenes. This reaction was first reported in the 1940s by Kharasch^[a] and today is known as Kharasch addition or atom transfer radical addition (ATRA). Historically, ATRA reactions were conducted in the presence of radical initiators and light (high yields of monoadduct for ATRA of CX₄ to α-olefins, but low for styrene and methyl acrylate). Kharasch reported the use of several radical electrophiles in his new radical reaction as shown below.

(Ref. http://www.princeton.edu/chemistry/macmillan/group-meetings/NJ_ATRA.pdf)

Transition metal complexes of Fe, Ru, Co, Ni and Cu are particularly effective halogen transfer agents. Variety of alkenes and alkyl halides can be utilized and

can be conducted intermolecularly and intramolecularly. Atom transfer radical cyclization (ATRC) particularly attractive tool because it enables synthesis of functionalized ring systems.

Literature reference

[a] Kharasch, M.; Jensen, E.; Urry, W. Science 1945, 102 , 128. DOI:10.1126/science.102.2640.128; Kharasch, M. S.; Jensen, E. V.; Urry, W. H. J. Am. Chem. Soc. 1947, 69 , 1100. DOI:10.1021/ja01197a035; Kharasch, M. S.; Kuderna, B. M.; Urry, W. J. Org. Chem. 1948, 13, 895. DOI:10.1021/jo01164a020
・ Minisci, F. Acc. Chem. Res. 1975, 8, 165. DOI: 10.1021/ar50089a004

Reaction mechanism

Example of reactions

N– Allyltrichloroacetamides having an appropriate cyclohexenyl or cyclopentenyl group, were easily cyclized to the corresponding trichlorinated ganma-lactams via CuCl or Ru catalysis.^[1]

Bibliography

[1] Nagashima, H.; Ara, K.-i.; Wakamatsu, H.; Itoh, K. J. Chem. Soc., Chem. Commun. 1985, 518. DOI: 10.1039/C39850000518

Related Books

Related Links

・Kharasch addition - Wikipedia
・Kharasch reaction and related transformation (Baran's group, PDF) 
・Metal Catalyzed Redox Reaction (MacMillan's Group. PDF)