Direct Conversion of Alcohols to α‑Chloro Aldehydes and α‑Chloro Ketones

Direct conversion of primary and
secondary alcohols into the corresponding
α-chloro aldehydes and α-chloro ketones using trichloroisocyanuric
acid, serving both as stoichiometric oxidant and α-halogenating
reagent, is reported. For primary alcohols, TEMPO has to be added
as an oxidation catalyst, and for the transformation of secondary
alcohols (TEMPO-free protocol), MeOH as an additive is essential to
promote chlorination of the intermediary ketones.