Borohydride, sodium reaction with enamines, imines

Phosphorylated allenes 195 (R1 = H or Me) are a source of secondary ( )-allylamines. The allenes are treated with an amine R2NH2 (R2 = t-Bu or 4-MeCgH4 and the products, which exist as equilibrium mixtures of enamines 196 and imines 197, are olefinated by successive reaction with methyllithium and an aldehyde R3CHO (R = i-Bu, 4-MeCgH4, PhCH2CH2 etc). Reduction with sodium borohydride finally yields the... 

Azides into Amines 20,23,771,772 H2/Pd or H2/Pt 317,318,339,450,773 H2/Pd-(Boc)20 in N-acyloxazolidinoncs to prevent reaction of the amine with the chiral auxiliary 774 Raney nickel 444 SnCh 444,450,458,775,776 Zn 777 Al/Hg 777 sodium borohydride under phase-transfer conditions 778 lithium aluminum hydride 779 H2S 780 triphenylphosphine.325,781,782 Azides into Imines base.783 785 Azides into Enamines NaReC>4.331... 

In a study of the reduction of steroidal imines with lithium aluminium hydride and sodium borohydride, Lusinchi9 found that with an excess of lithium aluminium hydride the methoxylated imine (8) afforded the two isomeric imines, (12) and (13), together with N-demethylconanine (14), in a ratio dependent on the time of the reaction. The absence of iV-demethylheteroconanine indicated that the reduction at position 20 was stereospecific. The imine (12) was found to result from initial reduction of the 20-N-imine, while the imine (13) was suggested to be derived from an enamine derivative, as in Scheme 1. 

Aldolases produce an imine as the initial intermediate from the reaction of a carbonyl group of the substrate with the c-amino group of a lysine residue of the enzyme (Scheme 4). Reactions of this adduct produce enamines that are tautomers of imines. The imine derivatives of the enzyme can be trapped irreversibly (Scheme 5) by reducing agents, such as sodium borohydride, and by nucleophiles, such as cyanide (5). The enamine structure has a zwitterionic resonance contributor with negative charge localized at the carbon a to the carbon attached... 

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