Science of Synthesis

Margaretha, P., Science of Synthesis, (2007) 35, 82.

Both N-chlorosuccinimide and trichloroisocyanuric acid [1,3,5-trichloro-1,3,5-triazine-2,4,6(1H,3H,5H)-trione] are used as co-reagents with triphenylphosphine for the facile replacement of hydroxy by chlorine with inversion of configuration. The imide formed as a byproduct can be easily removed by a preliminary extraction with water, the chloroalkane being soluble in an organic solvent, whereas the triphenylphosphine oxide is precipitated by the addition of pentane. Thus, 3β-chloro-5α-androstan-7-one can be obtained in 76% yield by treatment of the corresponding sterol with triphenylphosphine and N-chlorosuccinimide in tetrahydrofuran as the solvent,[‌79‌] and various chlorodeoxysugars are obtained by using the same reagents in dimethylformamide.[‌80‌] For trichloroisocyanuric acid, all three chlorine atoms are utilized in the exchange reaction, and therefore a 0.35:1 molar ratio of trichloroisocyanuric acid/triphenylphosphine is used; anhydrous acetonitrile is the solvent in the conversion of decan-1-ol into 1-chlorodecane (‌38‌) (‌Scheme 29‌).[‌81‌]

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References