Oppenauer oxidation unsaturated alcohols

Vicinal effects can also play a part in the course of the reaction utilizing Oppenauer conditions. 1,3-Diols or / -amino alcohols may not react, presumably on account of formation of an aluminum complex.5 5 46b> If oxidation were to take place it would probably be followed by dehydration to give an unsaturated ketone. Retro-aldol cleavage has been found to occur with a 17,21-dihydroxy steroid.32 The 11 -hydroxyl group which is generally inert to Oppenauer oxidation will react if a hydroxyl group is present on the... 

A number of non-steroidal unsaturated alcohols have been oxidized using the Oppenauer procedure.2,3 For example, bicyclic alcohol 20 was oxidized to the corresponding... 

Oppenauer applied this reaction to the oxidation of unsaturated steroidal alcohols using aluminum triiso-propoxide [Al(0/-Pr)3] in acetone. 37 The acetone acts as a hydrogen acceptor and the presence of excess acetone drives the reaction toward the oxidation product. Oppenauer used this method to oxidize the alcohol... 

The following observations indicate the position of the double bond and of one of the secondary hydroxyls Oppenauer oxidation of veratramine affects only one of the hydroxyls to yield an a,/3-unsaturated ketone, Cj7H3702N, (XLIII) which was isolated as its crystalline hydrochloride. iV-Acetylveratramine (XXIX) similarly yields the analogous iV-acetyl derivative, C29H39O3N. Reduction of the unsaturated ketone (XLIII) serves to form a mixture of epimeric alcohols, C27H39O2N (XLIV... 

Recent advances in alcohol oxidations by rhodium and iridium complexes have mainly focused on Oppenauer-type oxidations or reactions in which this type of oxidation is an intermediate step. An independent result is the oxidation of allyhc (Eq. 9) and benzyUc alcohols with f-BuOOH to the corresponding a,/l-unsaturated ketones [38] with [Rh2(p.-OAc)4]. The reactions were carried out at room temperature in dichloromethane and yields of up to 92% (by GC) in 24-48 h have been described. 

The reversible nature of the above reaction was demonstrated by Verley5 in 1925 and shortly thereafter by Pondorff,6 but it was not until 1937 that Oppenauer showed that unsaturated steroid alcohols 5 could be oxidized to the corresponding ketones 6 through action of aluminum /-butoxide in the presence of a large amount of acetone in excellent yields.1... 

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