15780-23-1Relevant academic research and scientific papers
METAL-ASSISTED REACTIONS-12. UNUSUAL SELECTIVITY IN THE REDUCTION OF KETONES WITH ZINC OR CADMIUM BIS-TETRAHYDROBORATE/DIMETHYLFORMAMIDE COMPLEX
Hussey, Brendan J.,Johnstone, Robert A. W.,Boehm, Peter,Entwistle, Ian D.
, p. 3769 - 3774 (1982)
Zinc bis-tetrahydroborate forms a solid complex with dimethylformamide (DMF) of composition, Zn(BH4)2*1.5DMF.Unlike zinc bis-tetrahydroborate itself, the complex with DMF can be stored as a solid at room temperature.Ketones and aldehydes are reduced to the corresponding alcohols by the complex but the mechanism of reduction appears to be different from that using zinc bis-tetrahydroborate itself and from other tetrahydroborates in that only one hydride equivalent from each BH4- unit is utilized and not four.Further, although saturated aliphatic ketones are reduced rapidly to alcohols, aromatic ketones react much more slowly and α,β-unsaturated ketones react very slowly so that the complex appears to have selective reducing potential with regard to different classes of ketones.It is also apparent that the zinc bis-tetrahydroborate/DMF complex reduces sterically hindered saturated ketones much more slowly than it does unhindered ketones.An analogous cadmium bis-tetrahydroborate/DMF complex can be prepared in solution and reacts with ketones similarly to the zinc complex.
SELECTIVITE DE LA REDUCTION DE L'ANDROSTEN-4 DIONE-3,17 ET DE LA PROGESTERONE PAR DIVERS BOROHYDRURES: ROLE DE L'ASSISTANCE ELECTROPHILE PAR LE CATION OU UN SOLVANT HYDROXYLE
D'Incan, E.,Loupy, A.,Restelli, A.,Seyden-Penne, J.,Viout, P.
, p. 1755 - 1760 (2007/10/02)
The reduction of Δ4-androsten-3,17 dione 1 and of progesterone 2 by nBu4NBH4 is highly chemisoselective: in THF only the α-enone moiety is reduced, the saturated C17 or C20 keto group being kept unchanged.When TMEDA is added, saturated alcohols are obtained, without any allylic alcohol when the reaction goes to completion.However this reduction is poorly stereoselective as 70:30 mixtures of A/B cis and trans ring junction compounds are obtained.In MeOH, the saturated keto group is more than 90percent selectively reduced.However, the reduction of 1 and 2 by LiBH4 and Zn(BH4)2 is poorly chemioselective.These results are interpreted in terms of competition between electrophilic assistance and steric effects.
