Sodium triacetoxyborohydride

Abstract

(A) Boros et al. recently reported the synthesis of diazaindoline 3, where the key step involved rapid reductive amination of aldehyde 1 with aniline 2 by sodium triacetoxyborohydride (STAB-H) and TFA.6 (Figure presented). (B) A tandem reductive aminationlactamization strategy using STAB-H, 1-benzyl-4-piperidone (4) and γ- or δ-amino esters or acids resulted in lactam 57 (Figure presented). (C) Dialdehyde 6 can be converted into amine 7 with STAB-H and benzylamine, whereas lactol 8 likewise affords lactam 9 under similar conditions.8,9 (Figure presented). (D) As mentioned already, STAB-H is a milder reducing agent than NaBH4 and hence selective. It can reduce vinylogus carbamate 10 selectively without affecting other functionalities.10 (Figure presented). (E) The reduction of an imine can be effected by STAB-H. The reduced form of the quarter pyrroles 13 can be obtained by using STAB-H from the stable oxidized form 12.11 (Figure presented). (F) It is shown that STAB-H effectively reduced amide 14 to 15 in the total synthesis of a selective D1 antagonist useful in the treatment of psychoses, depression, and D1-dependent neurological disorders.12 (Figure presented). (G) Cleavage of oxazolidines 16 can easily be carried out with STAB-H13 to provide 17 and this tactic was featured in the first enantiospecific synthesis of salinosporamide A. 14 (Figure presented). © Georg Thieme Verlag Stuttgart New York.