Potassium tri-sec-butylborohydride

Reduction of steroid ketones. Steroid 3-ketones can be reduced selectively by potassium tri-sec-butylborohydride in the presence of 17- and 20-keto groups to the 3-axial alcohol (3a-OH for 5a-steroids 3/f-OH for 5/J-steroids). 

REDUCTION, REAGENTS Aluminum amalgam. Borane-Dimethyl sulfide. Borane-Tetrahydrofurane. t-Butylaminoborane. /-Butyl-9-borabicyclo[3.3.1]nonane. Cobalt boride— f-Butylamineborane. Diisobutylaluminum hydride. Diisopropylamine-Borane. Diphenylamine-Borane. Diphenyltin dihydride. NB-Enantrane. NB-Enantride. Erbium chloride. Hydrazine, lodotrimethylsilane. Lithium-Ammonia. Lithium aluminum hydride. Lithium borohydride. Lithium bronze. Lithium n-butylborohydride. Lithium 9,9-di-n-butyl-9-borabicyclo[3.3.11nonate. Lithium diisobutyl-f-butylaluminum hydride. Lithium tris[(3-ethyl-3pentylK>xy)aluminum hydride. Nickel-Graphite. Potassium tri-sec-butylborohydride. Samarium(II) iodide. Sodium-Ammonia. Sodium bis(2-mcthoxyethoxy)aluminum hydride. 

For the synthesis of the 11-thia-prostanoid analog of the F-series 138, the ketone 131 was reduced with potassium tri-sec.-butylborohydride (K-Selectride), followed by using the methods described above. 

Lithium and potassium tri-sec-butylborohydride (L- and K-Selectride) selectively reduce the olefin of many a,g-unsaturated carbonyl compounds.79 The intermediate enolate anions may also be trapped by electrophiles, providing a regiospecific reductive alkylation of a,g-unsaturated carbonyl compounds. 

Compare Potassium tri-sec-butylborohydride—Cuprous iodide, this volume. 

Potassium tri-sec-butylborohydride, K(sec-C4H9)3BH. Mol. wt. 222.27. Supplier Aldrich (K Selectride). 

Reduction of cyclic ketones. Potassium tri-sec-butylborohydride is equal or superior to hthium tri-sec-butylborohydride (4, 312-313) for stereoselective reduction of cyclic ketones. 

Conjugate reduction. Cyclohexenones unsubstituted at a 3-position are reduced by potassium tri-sec-butylborohydride to the corresponding saturated ketones in nearly quantitative yield. The reaction can be conducted in THF or ether—THF and is rapid even at -78°. An example is the reduction of (1) to... 

Cuprous bromide-Sodium bis(2-methoxyethoxyl)aluminum hydride. Lithium aluminum hydride-Cuprous iodide. Potassium tri-sec-butylborohydride. 

Potassium hydroxide, 20, 239, 303-304 Potassium persulfate, 274 Potassium superoxide, 304-307 Potassium tri-sec-butylborohydride, 307 Prins reaction, 159 Progesterone, 107 Proline, 10, 307 1,3-Propanediol, 37 Propargylic alcohols, 8, 53 Propargylic chlorides, 155 (E)-Propenyllithium, 141 Propiolaldehyde diethyl acetal, 79-80 Propiolamidium salts, 124 Fropiolate esters, 8 Propiolic add, 295 Propylene carbonate, 74 Propylene oxide, 74 Protolichesterinic add, 412 Pterocarpins, 114 Pulegone, 287, 288, 308-309 tosylhydrazones, 375-376 Pulvinic acid pigments, 291 Pumiliotoxin, 28... 

Henkel-Loctite appears to have been careful to avoid the patent minefield laid by 3M and Dow. Their patent strategy in this field has involved mainly the use of metal alkali borohydrides [113,114], or tetralkylboranes [115-117]. In particular, alkali metal trialkyl borohydrides are used, the alkali metal salt being selected from lithinm triethylborohydride, sodium triethylborohydride, potassium triethylborohydride, lithium tri-sec-butylborohydride, sodium tri-sec-butylborohydride, potassium tri-sec-butylborohydride, and lithium triethylborodeuteride. 

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