α-Nitro Keto Hydrazone and Keto Imine Dianions. Synthetic Equivalents for the Nitroalkene d3 Synthon

Article abstract of DOI:10.1021/jo00241a024

A general method for the preparation of 3-substituted nitrocycloalkenes has been developed. 2-Nitrocycloalkanones are transformed into iether α-nitro N,N-dimethylhydrazones or α-nitro cyclohexylimines, which exist exclusively in the aci-nitro form.Double deprotonation of these materials with sec-BuLi produces higly reactive dianions which can by alkylated with methyl, allyl, n-butyl, isopropyl, or 4-hexenyl iodides in excelent yields.The alkylation occurred uniformly next to the hydrazone or imine function.The alkylated α-nitro hydrazones are converted to nitroalkenes by reduction with NaBH4 followed by elimination induced by heating (120 deg C) with acetic anhydride.The alkylated α-nitro imines undergo facile reduction-elimination with NaBH4/CeCl3 ar room temperature.The overal yield for 2-nitro ketone to nitroalkene transformation ranged from 35percent to 44percent for the hydrazone method and from 19percent to 39percent for the imine method.