Categories: C-Cl Bond Formation >
Synthesis of allyl chlorides
AcCl-EtOH transforms primary and secondary allyl acetates into allyl chlorides that retain the olefinic bond in the more stable position. Secondary allyl alcohols react with almost the same efficacy as the acetates, but the reactions of primary allyl alcohols that possess 1,2-disubstituted alkenes are very slow. Simple removal of the volatiles gives products in high purity.
V. K. Yadav, K. G. Babu, Tetrahedron, 2003, 59, 9111-9116.
A versatile and scalable protocol involving the activation of DMSO by chlorotrimethysilane enables a chemoselective chlorination of polyprenoids. This simple protocol provides an alternative to existing routes for accessing useful synthetic precursors of complex terpenoids.
V. P. Demertzidou, S. Pappa, V. Sarli, A. L. Zografos, J. Org. Chem., 2017, 82, 8710-8715.
The use of chloro tropylium chloride enables a rapid generation of alkyl halides and acyl chlorides from alcohols and carboxylic acids under very mild reaction conditions via aromatic tropylium cation activation. This reactions demonstrate the synthetic potential of tropylium cations in promoting chemical transformations.
T. V. Nguyen, A. Bekensir, Org. Lett., 2014, 16, 1720-1723.
Aryl allylic alcohols are converted to halogenated unsaturated ketones or allylic halides under Moffatt-Swern Conditions using excess DMSO and oxalyl chloride or oxalyl bromide. Electron-poor aromatic rings favor formation of the halogenated ketone, while electron-donating substituents in the ortho or para positions favor formation of the allylic halide.
J. Yin, C. E. Gallis, J. D. Chisholm, J. Org. Chem., 2007, 72, 7054-7057.
Activating of magnesium alkoxides using TiCl4 allows the generation of allylic chlorides. An efficient, one-pot method for the conversion of carbonyl electrophiles to allylic chlorides has been developed.
M. J. Fuchter, J.-N. Levy, Org. Lett., 2008, 10, 4919-4922.
Titanium(IV) halides mediate a highly stereoselective vicinal difuctionalization of α,β-unsaturated ketones to provide multifunctionalized trisubstituted alkenes in very good yields and high Z:E stereoselectivity. The reaction can be performed at room temperature in a convenient vial under air.
G. Li, J. Gao, H.-X. Wei, M. Enright, Org. Lett., 2000, 2, 617-620.