Alcohols catalytic halogenation

Catalytic Halogenation of Alcohols and their Silylated Derivatives... 

The introduction of tritium into molecules is most commonly achieved by reductive methods, including catalytic reduction by tritium gas, PH2], of olefins, catalytic reductive replacement of halogen (Cl, Br, or I) by H2, and metal pH] hydride reduction of carbonyl compounds, eg, ketones (qv) and some esters, to tritium-labeled alcohols (5). The use of tritium-labeled building blocks, eg, pH] methyl iodide and pH]-acetic anhydride, is an alternative route to the preparation of high specific activity, tritium-labeled compounds. The use of these techniques for the synthesis of radiolabeled receptor ligands, ie, dmgs and dmg analogues, has been described ia detail ia the Hterature (6,7). 

Halogen-lithium exchange of iodide 71 and subsequent addition of 2-acetyl-furan (72) to the resultant organolithium intermediate yielded two diastereomeric tertiary alcohols (dr=l l), which were converted to (E)-olefin 73 with complete diastereoselectivity upon brief exposure to catalytic amounts of concentrated aqueous hydrogen chloride (Scheme 11) [18]. Diastereoselective hydroboration/oxidation of 73 gave largely the desired stereoisomer 74 due to... 

Alcohols may be prepared (1) by hydration of alkenes (1) in presence of an acid and (11) by hydroboratlon-oxidatlon reaction (2) from carbonyl compounds by (1) catalytic reduction and (11) the action of Grignard reagents. Phenols may be prepared by (1) substitution of (1) halogen atom In haloarenes and (11) sulphonic acid group In aiyl sulphonic acids, by -OH group (2) by hydrolysis of diazonium salts and (3) industrially from cumene. 

Catalytic hydrogenation is hardly ever used for this purpose since the reaction by-product - hydrogen chloride - poses some inconveniences in the experimental procedures. Most transformations of acyl chlorides to alcohols are effected by hydrides or complex hydrides. Addition of acyl chlorides to ethereal solutions of lithium aluminum hydride under gentle refluxing produced alcohols from aliphatic, aromatic and unsaturated acyl chlorides in 72-99% yields [5i]. The reaction is suitable even for the preparation of halogenated alcohols. Dichloroacetyl chloride was converted to dichloro-... 

---