Categories: C-Cl Bond Formation >
Synthesis of 1,2-dichloroalkanes
Recent Literature
An operationally simple triphosgene-pyridine activation enables the conversion
of unactivated terminal aliphatic epoxides to alkyl vicinal dichlorides. The
methodology tolerates a broad of scope of substrates as well as protecting
groups. Furthermore, these mild conditions generally yield clean reaction
mixtures that are free of byproducts upon aqueous workup.
A. H. Cleveland, F. R. Fronczek, R. Kartika, J. Org. Chem., 2018, 83,
3367-3377.
A catalytic Appel reaction using a P(III)/P(V) redox cycling at very low
catalyst loadings, hexachloroacetone as the halogen source and phenylsilane as
the terminal reductant converted alcohols and epoxides containing a wide variety
of functional groups to the respective chlorides and dichlorides in very good
yields and with high enantiospecificities for inversion.
J. Tönjes, L. Kell, T. Werner, Org. Lett., 2023, 25,
9114-9118.
A stereospecific triphenylphosphine oxide-catalyzed 1,2-dichlorination reaction
of epoxides is effective for a range of terminal and internal epoxides. In
contrast to the classical Appel-type dichlorination of epoxides, oxalyl chloride
is used as a stoichiometric reagent to generate the chlorophosphonium salt
responsible for dichlorination from catalytic triphenylphosphine oxide.
R. M. Denton, X. Tang, A. Przeslak, Org. Lett., 2010,
12, 4678-4681.
A Ph3P/I--promoted dihalogenation of epoxides provides
1,2-dihalides in the presence of XCH2CH2X (X = Cl or Br)
as the solvent and halogen source. All reagents are widely available and easy to
handle. The protocol offers mild conditions and operational simplicity.
J. Long, J. Chen, R. Li, Z. Liu, X. Xiao, J.-H. Ling, X. Zheng, J.-C. Xiao, Synlett, 2019,
30,
181-184.
The use of Selectfluor as an oxidant and tetrabutylammonium bromide/chloride
salts as a halogen source enables a metal-free and molecular halogen
reagent-free dihomohalogenation methodology. This effective strategy provides
various fluorine-free halogenated products easily in quantitative yields from
alkenes, alkynes, and natural products.
Z. Dağalan, R. Koçak, A. Daştan, B. Nişancı, Org. Lett., 2022, 24,
8261-8264.
A Mn-catalyzed electrochemical dichlorination of alkenes with MgCl2
as the chlorine source provides an operationally simple, sustainable, and
efficient access to a variety of vicinally dichlorinated compounds. In
particular, alkenes with oxidatively labile functional groups, such as alcohols,
aldehydes, sulfides, and amines, were transformed into the desired vicinal
dichlorides with high chemoselectivity.
N. Fu, G. S. Sauer, S. Lin, J. Am. Chem. Soc., 2017,
139, 15548-15553.
A mild and efficient protocol enables the preparation of 1,2-dichloroalkane
derivatives from olefins in the presence of NH4Cl and Oxone at room
temperature. Various terminal, internal, and cyclic alkenes reacted smoothly to
give the corresponding dichlorinated products in good to excellent yields.
Internal olefins dichlorinated with moderate to excellent diastereoselectivity.
P. Swamy, M. M. Reddy, M. A. Kumar, M. Naresh, N. Narender, Synthesis, 2014, 46,
251-257.