Some aspects of NaBH(4) reduction in NMP.
In our solvent optimization study of NaBH(4) reduction, NMP was found to enhance the reactivity. A chemoselective debromination of the bromide and sulfonates can be attained in the new borohydride reagent system: NaBH(4)-LiOTf-NMP. This mixed system worked as an alternative to NaBH(3)CN and Bu(3)SnH for the S(N)2 type displacement of alkylbromide and sulfonate. Also mentioned is an expedient reduction of an azide group into amine by NaBH(4) in NMP without any additive, which offers a convenient protocol for the direct transformation of halides into amines via azide in one flask. Some examples of other reductions were also presented.
Torisawa
Yasuhiro
Y
Process Research Laboratory, Second Tokushima Factory, Otsuka Pharmaceutical Co. Ltd., Kawauchi-cho, Tokushima 771-0182, Japan. torisawa@fact.otsuka.co.jp
Nishi
Takao
T
Minamikawa
Jun-ichi
J
D001386:Azides / Q000737:chemistry; D001894:Borohydrides / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D006842:Hydrocarbons, Brominated / Q000737:chemistry; D010084:Oxidation-Reduction; D011759:Pyrrolidines / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
D001386:Azides; D001894:Borohydrides; D006842:Hydrocarbons, Brominated; D011759:Pyrrolidines; D012997:Solvents; C054965:N-methylpyrrolidine; C025364:sodium borohydride