Diisobutyl-aluminium hydride, reduction

The Stephen s method allows the reduction of nitriles by stannous chloride in acid medium. If the amine chlorhydrate initially formed is hydrolyzed, the corresponding aldehyde is obtained (37, 91). Harington and Moggridge (37) have reduced 4-methyl-5-cyanothiazole by this method (Scheme 23). However, Robba and Le Guen (91) did not obtain the expected products with 4.5-dicyanothiazole and 2-methyl-4,5-dicyanothiazole. These compounds have been reduced with diisobutyl-aluminium hydride with very low yields (3 to 6%) (Scheme 24). In other conditions the reaction gives a thiazole nitrile aldehyde with the same yield as that of the dialdehyde. 

Detty published the first example of the titled approach in his pioneering work on teluropyrans (88MI1). The hexafluorophosphate 76 was reduced with diisobutyl aluminium hydride (DIBAL-H) to a 93 7 mixture of isomeric teluropyrans 77 and 78 accompanied by traces (ca. 1%) of the dimeric product 80. The latter was also obtained after the electrochemical reduction of 76 via radicals 79 or by a modification of the reduction with DIBAL-H (Scheme 5). 

Since sulphones 204 are easily available compounds one would expect that they could be used as starting materials for the preparation of sulphoxides via the selective removal of one oxygen atom from the sulphonyl group (equation 112). Up to now, there is only one example reported of a direct reduction of a sulphone to a sulphoxide. The bicyclic dideuterio sulphone 205 after 24 h treatment with three-fold excess of diisobutyl aluminium hydride in boiling dichloromethane gave the corresponding sulphoxide 206 in 36% yield (equation 113). A two-step procedure for the selective reduction of sulphones to sulphoxides, which involves an initial reaction of sulphone 204 with aryldiazonium tetrafluoroborate 207 to form aryloxysulphoxonium salt 208 and its subsequent reduction (equation 114), was alluded to by Shimagaki and coworkers and... 

Oxidation of the hydroxyl group in 186 with pyridinium chlorochromate (PCC) in CH2CI2 affords the aldehyde 197. The reduction of 197 back to 186 is possible in EtOH in the presence of TiCl4, whereas upon treatment of 197 with diisobutyl-aluminium hydride a competitive reaction with the fullerene core was observed. 

Stronger hydrides can reduce carbonyl groups of dihydropyrimidinediones, and thus both L1A1H4 and diisobutyl-aluminium hydride regioselectively gave the 4-hydroxy derivative 540 on reduction of the 5,6-dihydro-2,4-pyrimidi-nedione 539 <2001TL8629>. 

The aldehyde moiety of 50 can be condensed with either amines or active methylene compounds. In the case of reactions with amines, the aldehyde 50 (presumably obtained by reduction of the cyano group with diisobutyl-aluminium hydride (DIBAL-H)) forms simple Schiff bases 51 (Equation 20) <1998J(P1)3557>. 

Two pseudo-sugars of P-L-allo and a-D-manno have been prepared from the preceding intermediate 143 as follows. Reduction of 143 with diisobutyl aluminium hydride afforded the 3-hydroxyl derivative (155), which gave the 3-O-acetyl derivative (156) on acetylation. Hydroxylation of 156 with osmium tetroxide and hydrogen peroxide gave the compound (157), m.p. 154-155 °C, [a] 1 +71.5° (chloroform), as a main component (53% yield) and an unidentified compound, m.p. 191-193 °C, [a.] —7.9° (chloroform), as a minor component (6% yield). On acetylation, 157 was converted into the tri-0-acetyl derivative (158), m.p. 66-67 °C, [a]23 +41.8° (chloroform). 

Vinyloxiranes are reduced very selectively by diisobutyl-aluminium hydride (Eq. 168). Without regard to the configuration (exo,endo), the reduction of norborn-ane diepoxides with LiAlH proceeds in such a manner that the norbornane moiety remains intact in the reaction. (Eq. 168). ... 

Zakharkin, L.L, and Khorlina, I.M., Preparation of aldehydes by reduction of nitriles with diisobutyl-aluminium hydride, Dokl. Akad. Nauk SSSR, Ser. Khim., 116,422,1957 Chem. Abstr, 52, 8040f. 1958. 

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