title: Reductive Chlorination and Bromination of Ketones via Trityl Hydrazones.
abstract: A method is presented for the direct transformation of a ketone to the corresponding reduced alkyl chloride or bromide. The process involves the reaction of a ketone trityl hydrazone with tBuOCl to give a diazene which readily collapses to the α-chlorocarbinyl radical, reduction of which by a hydrogen atom source gives the alkyl chloride product. The use of N-bromosuccinimide provides the corresponding alkyl bromide. This unique transformation provides a reductive halogenation that complements Barton's redox-neutral vinyl halide synthesis.
authors.affiliation: Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, IL, 60637, USA.
authors.forename: Julius R
authors.initials: JR
authors.lastname: Reyes
authors.affiliation: Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, IL, 60637, USA. vrawal@uchicago.edu.
authors.forename: Viresh H
authors.initials: VH
authors.lastname: Rawal
mesh_terms: D001966:Bromine / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry*; D006835:Hydrazones / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D006835:Hydrazones; D007659:Ketones; D002713:Chlorine; D001966:Bromine
keywords: diastereoselectivity; halogenation; hydrazones; radical reactions; synthetic methods
references.citation: J Am Chem Soc. 2004 May 5;126(17):5436-45
references.pmid: 15113215
references.citation: Nat Prod Rep. 2011 Jan;28(1):15-25
references.pmid: 21125121
references.citation: J Am Chem Soc. 2014 Jan 29;136(4):1300-3
references.pmid: 24428640
references.citation: Alkaloids Chem Biol. 2014;73:161-222
references.pmid: 26521650
references.citation: Chem Commun (Camb). 2003 Jan 21;(2):204-5
references.pmid: 12585392
references.citation: Chem Rev. 2013 May 8;113(5):3632-85
references.pmid: 23448097
references.citation: Chem Pharm Bull (Tokyo). 1963 Nov;11:1413-7
references.pmid: 14090590
references.citation: J Am Chem Soc. 2014 May 14;136(19):6884-7
references.pmid: 24824195
references.citation: Chem Rev. 2014 Mar 12;114(5):2587-693
references.pmid: 24383397
references.citation: Proc Natl Acad Sci U S A. 2004 Aug 17;101(33):12054-7
references.pmid: 15280544
references.citation: J Am Chem Soc. 2014 Oct 22;136(42):14710-3
references.pmid: 25275668
references.citation: Chem Commun (Camb). 2011 Sep 14;47(34):9705-7
references.pmid: 21792443
references.citation: Org Lett. 2014 Sep 5;16(17):4460-3
references.pmid: 25124334
references.citation: Chem Rev. 1969 Dec;69(6):785-97
references.pmid: 4901998
references.citation: Nature. 2014 Dec 18;516(7531):343-8
references.pmid: 25519131
references.citation: J Am Chem Soc. 2008 Jan 30;130(4):1148-9
references.pmid: 18181631
references.citation: Tetrahedron. 2011 Dec 30;67(52):100997-10104
references.pmid: 22962500