Diastereoselective LiAlH4 reduction of chiral ketone hydrazones derived from (R)-(-)-2-aminobutan-1-ol

Various chiral N,N-dialkylhydrazines were prepared in four to five steps fr om (R)-(-)-2-aminobutan-1-ol 6. They reacted with various prochiral ketones , thus giving the corresponding hydrazones. Reduction of the latter by mean s of LiAlH4 afforded N,N,N'-trisubstituted hydrazines whose d.e.s were in t he range 43-100%. Interestingly, LiAlH4 reduction of the four N-trifluoroet hylhydrazones 34 and 38-40 yielded the hydrazines 46 and 48-50, respectivel y, and with d.e.s = 100% by H-1 and C-13 NMR. (C) 2000 Elsevier Science Ltd . All rights reserved.