Configuration of 2-Hydroxyputrescine

Abstract S-(+)-2-hydroxyputrescine·2HCl and R-(-)-2-hydroxy-putrescine·2HCl were synthesized from S-(-)- and R-(+)-hydroxysuccinamide, respectively. Their specific rotations were determined to be [α]25°d = +3.21 ± 0.06° and -3.3° (c = 5%, H2O), respectively. The naturally occurring polyamine isolated from Pseudomonas (Kim) appears to be S-2-hydroxyputrescine since the specific rotation of its dihydrochloride corresponds closely to that of the synthesized S-(+)-2-hydroxyputrescine dihydrochloride.

11-c have previously shown that a pseudomonad which contains no spermidine (1) contains 2-hydroxyputrescine (2, 3). Derivatires of this polJ-amine have also been found in rust-resistant wheat leaves (4). Tohari and Tchen (5) hare confirmed the presence of this pclyamine in the p~eudomonad and have reported its specific rotation to be + 16.8", but they have not determined its absolute configuration.
Stoessl ef al. (4) have assigned the chirnlity hy a comparison of the melting ranges of 1 : 1 mixtures of the dihydrochlorides de1 ived from natural Rources with thr synthetic materials of known c~onfiguration.
The specific rotation of these "authentic specimens," however, is reported as +i" and -7" for the S-( +) and R-( -) isomers, respectively.
Our own results agree qualitatively with the?? findings but differ markedly numerically.
The specific rotation of the corresponding R isomer was found to be -3.3" (c = 5% w/v, HZO).
The amides which were used as the starting materials for the synthetic amines were prepared from R-and S-malic acid according to l)ublished procedures and their purity was established by a comparison of their melting points and specific rotations with the values in the literature (6,7).
The reduction to the hydroxydiamine was at first performed by means of lithium aluminum hydride, the prbcedure used by Stoessl et al. (4), and gave rather low yields. Xuch better results (approximately 75% yield) were obtained by the use of diborane in tetrahydrofuran solution (8,9).' The amide, 4.5 g (0.034 mole), was added in small par.. The reaction was carried out in a dry nitrogen atmosphere.
After 8 hours of reflux, 75 ml of 20% aqueous NaOH were added and the heating continued for one more hour. The reaction mixture was dried by means of NaOH pellets.
The solution was separated from the formed cake and the solvent evaporated.
R-and S-2-hydroxyputlescine.2 HCl gave consistent infrared and NMR spectra (3), agreed with each other, with rncemic 2-hydroxyputrescine synthesized from 1,4-diaminohutanone (lo), and with the dihydrochloride of the naturally occurring 2-hydroxyputrescine in melting point, magnitude of the specific rotation, paper electrophoretic mobility, and retention time on chromatographic columns.3 Uecau:e of the discrepancy between the values which we obtained for the specific rotations and those which were ohrelved by Tobari and Tchen (5) and Stoessl et al. (4), we have examined the concentration dependence of the specific rotation of the S isomer, since such a dependence, if existent, could very well account for the reported differences.
We have found no recognizable trend of concentration dependence for aqueous solutions in the range from 0.5 to 15y0 (w/v).
We have therefore calculated the mean value of the specific rotation [a]t5' = +3.21 i= 0.06" (S.D.) from ten of our measurements.
Bc~nowledgments--We are grateful to Mrs. L. JV. Hurley and l\Irs. C. -4. Edwards for determining the specific rotations.