Chloral secondary alcohols

Chloral or benzaldehyde in the presence of dehydrated alumina48 and Al(OtBu)3 in the presence of f-BuOOH,49 are oxidizing systems reminiscent of Oppenauer oxidations that can perform regioselective oxidations of secondary alcohols. 

The method given here is essentially that of Meerwein and his pupils Schmidt5 and von Bock.3 The theory of the reaction and applications are also discussed by Dworzack 4 and by Ver-ley.6 A number of patents have appeared covering this reaction, in some of which a secondary alcohol such as isopropyl alcohol 7 is used in place of ethyl alcohol. Trichloroethyl alcohol is one of the chlorination products of alcohol and is found in the high-boiling fractions in the production of chloral.8 It was prepared by Garzarolli-Thurnlackh 9 and by Delacre10 by the action of diethylzinc on chloral. 

Aldehydes and ketones undergo reduction to primary and secondary alcohols (e.g. chloral is converted to trichloroethanol and prednisone is reduced to prednisolone). 

Chloral (trichloroacetaldehyde), CCI3CHO, oxidizes secondary alcohols to ketones in the presence of very active aluminum oxide (Woelm). This reaction seems to be superior to the Oppenauer oxidation, because it takes place at room temperature or at only slightly elevated temperatures [958, 959, 960],... 

Chloral is used as the hydrogen acceptor in the quantitative oxidation of cyclobutanol to cyclobutanone. The reaction takes place on Woelm alumina at room temperature in carbon tetrachloride after 24 h [95S]. Under similar conditions, primary alcohols are oxidized in preference to secondary alcohols [959]. 

Oxathietan 1,1-dioxide (130) reacts with alcohols to give (2-fluorosulphonyl)-carboxylic esters, and with BFj and EtjN to give fluorosulphonyl(trifluoro-methyl)keten. The latter reaction is more efficient if the ring is first opened with KF and HF. Chloral cyclo-adds to sulphenes to give yff-sultones. 4-Tri-chloromethyl-l,2-oxathietan 2,2-dioxide reacts with primary and secondary amines to give y5-hydroxy-sulphonamides. ... 

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