摘要：StoichiometryDependence in the Consecutive, Competing Reduction, Halogenation,or Deoxygenation of Aryl Carbonyls

转自：康龙化成

StoichiometryDependence in the Consecutive, Competing Reduction, Halogenation,or Deoxygenation of Aryl Carbonyls

P.Veeraraghavan Ramachandran,* Henry J. Hamann, and Abdulkhaliq A. Alawaed

Departmentof Chemistry, Purdue University, United States

—J. Org. Chem. 2024, DOI: 10.1021/acs.joc.4c00869

Recommended by Bing Han_MC3

KEY WORDS: reduction (反应类型),reductive halogenation (反应类型), deoxygenation (反应类型),aryl carbonyls (原料),TiCl4 (试剂), borane-amine (试剂);C(sp3)-X,C(sp3)-O,C(sp3)-H(成键类型)

ABSTRACT: Six fundamental chemical transformations of aryl carbonyls are achievedby properly adjusting the stoichiometry of the borane-amine and titanium tetrachloride reagent system. This set of reagents actscollectively as a hydridedonor, Lewis acid catalyst, and halogen source for the reduction of carbonyls toalcohols, reductive halogenation of carbonyls to halides, deoxygenation ofcarbonyls to alkanes, dehydroxyhalogenation of alcohols to halides, deoxygenation ofalcohols to alkanes, and hydrodehalogenation of halides to alkanes. While thecarbonyl reduction is broadly applicable to both aromatic and aliphaticsubstrates, the remaining reactions are dependent on the stability of theproposed carbocationic intermediates, enabling highly selectivereactions at the substrates’ benzylic position. This unique selectivity allowsbenzylic dehalogenation in the presence of aryl and alkyl halides in additionto highly selective dehydroxyhalogenation of alcohols even for tertiary versussecondary aliphatic and secondary versus primary benzylic substrates using onlytitanium tetrachloride as the chlorinating agent.

Reactions of the BH3NH3/TiCl4Reagent System

Preliminary Examination Using Benzophenone

Selected Scope of TiCl4-CatalyzedCarbonyl Reduction Using BH3NH3

Selected Scope of Carbonyl ReductiveHalogenation Using BH3NH3 and TiCl4

Selected Scope of Carbonyl DeoxygenationUsing BH3NH3 and TiCl4

Selected Scope of Alcohol Dehydroxyhalogenation Using TiCl4

Deoxygenation of Benzylic Alcohols withAB

Hydrodehalogenation of Benzylic Alcohols

Prof. P.Veeraraghavan Ramachandran andcoworkers reported an efficient set of methods for the rapid performance of six fundamental chemical transformationsunder ambient conditions using a single set of reagents. Performing each of the six transformations[(A) carbonyl reduction, (B) carbonyl reductivehalogenation, (C) carbonyl deoxygenation, (D) alcohol dehydroxyhalogenation, (E) alcohol deoxygenation, and (F) hydrodehalogenation] onseveral sets of corresponding substrates allows several conclusions to bedrawn.The simplicity of the six relatedreactions presented, the broad scope of applicable substrates, and severalunique selectivity features arecertain to make this methodology a valuable addition to the tool kit of organicchemists.

来源：新浪财经