Swern oxidation of 2-substituted amino-1, 3-propanediols 20a-d, 38, 41, and 42 smoothly proceeded to give the oxidative dehydration products, 2-substituted aminopropenals 17a-d, 43, 45 and 46, respectively. Reaction of the intriguing 2-substituted aminopropenals 17a-d with N-benzyl-N'-methyl-or N, N'-dimethylethylenediamine (12o or 12p) followed by NaBH 4 reduction of the iminium salt intermediates afforded the corresponding 6-substituted ...