Synthesis of Vicinal Dichlorides via Activation of Aliphatic Terminal Epoxides with Triphosgene and Pyridine

Abstract

Herein we report a novel synthetic reaction to convert unactivated terminal aliphatic epoxide to alkyl vicinal dichloride based on triphosgene-pyridine activation. Our methodology is operationally simple and readily tolerated by 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.

Ph3P/I–-Promoted Dichlorination or Dibromination of Epoxides with XCH2CH2X (X = Cl or Br)

“…3). 8 In contrast to previous methods, no triphenylphosphine oxide was generated, and clean crude products could be obtained simply upon aqueous workup. However, the use of the hazardous reagent, triphosgene, may limit the synthetic utility of this method.…”

Triphosgene: an efficient chlorination reagent for synthesis of 5-chloro-2-pentanone from acetyl-n-propanol

“…Furthermore, BTC has been proven to be a convenient substitute to the extremely toxic phosgene and diphosgene gases. The transportation, storage, and operation of BTC are more practicable than phosgene and diphosgene gases because of its stable crystalline form [20]. Besides, the chlorination reactions with BTC require neither strict inert condition nor anhydrous condition, and can achieve excellent yield simultaneously [21].…”

Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols

“…In recent years, our group has developed methods to chlorinate primary and secondary alcohols using a mixture of triphosgene and amine bases, particularly triethylamine or pyridine . Recognizing that SOCl 2 or POCl 3 also serve as reagents for the chlorination of alcohols, we hypothesized that our triphosgene-amine base chemistries could be perhaps applied to dehydrate tertiary alcohols.…”