Lithium 9,9-di-n-butyl-9-borabicyclo

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. 

A zinc-modifled cyanoborohydride reagent, prepared in situ by the reaction of sodium borohydride with zinc chloride in ether, reduces tertiary halides in high yields, whereas primary and secondary halides remain intact. Similar reactivity is observed with lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]-nonanate (4), as shown in equation (5). ... 

Reversed regioselectivity has been observed in reduction with lithium 9,9-di-n-butyl-9-borabicyclo[3.3.1]nonate 122. This compound reduces aryl-substituted oxiranes a to the aryl groups (in the most-hindered position) and aliphatic oxiranes in the least-hindered position (Eqs. 165 and 166). ... 

Reduction of tertiary, aUylic, and benzyiic halides.1 NaCNBH3 and ZnCl2 in a 2 1 molar ratio in ether reduce these halides selectively in —70-90% yield in the presence of primary, secondary, vinyl, and aryl halides. The selectivity is comparable to that of lithium 9,9-di-/i-butyl-9-borabicyclo[3.3.1]nonate, the ate complex obtained by reaction of n-butyllithium with 9-BBN.2... 

---