to stand under nitrogen at room temperature for 10 days. The yellow solution was cooled in an ice bath, diluted with 200 ml of 95% aqueous EtOH, and treated with 8 g of NaBH4 (pellets) in portions over 3 min. The mixture was stirred at 0-5°for 1 hr and then at room temperature for 8 hr. The mixture was made strongly basic with 6 N NaOH and extracted with CH2CI2. The organic extract was washed with aqueous NaCl, dried, and concentrated to give a yellow foam. Chromatography over 15 g of activity III basic alumina gave, with benzene elution in four 30-ml fractions, a total of 0.32 g (55%) of 1 as a white solid, mp 151-152°. Recrystallization from ether gave tiny colorless crystals, mp 153-154°(lit.9 mp 152-153°). This material was identical (infrared, tic) with authentic l.5•9•12Ar-[2-(3-Indolyl)ethyl]piperidine ( 7).-To a stirred ice-cold solution of 0.50 g (0.0025 mol) of 2, 15 ml of a KH2PO4-NaHP04 concentrated 6.50 pH buffer solution (Radiometer, Copenhagen), 0.20 g (0.0032 mol) of NaCNBH3 (Alfa Chemical Co.) in 500 ml of distilled H20 was added dropwise over a few min 1.5 g (0.0038 mol) of'a 25% aqueous solution of 3. The solution (pH 6-7) was stirred at 0-5°for 1 hr and then allowed to stand at room temperature for 12 days. The mixture was made strongly basic with 6 N NaOH and extracted with CH2CI2. The organic extract was washed with water, dried, and concentrated to give 0.55 g of a white crystalline mass.
The synthesis of the protected stereo‐co‐oligopeptides with alternating D‐ and L‐valine residues Boc‐(D‐Val)m‐(L‐Val‐D‐Val)n‐OMe (m = 0; n = 1,2,3,4,6,8, and m = 1; n = 1,2,3,4) is described. The synthesis has been carried out by using conventional solution methods. The co‐oligopeptides up to the nonapeptide (m = 1; n = 4) have been prepared in a stepwise fashion. The dodecapeptide (m = 0; n = 6) and the hexadecapeptide (m = 0; n = 8) have been prepared by condensation of smaller peptides, and the criteria used for assessing their stereochemical purity are discussed. Preliminary characterization data are presented. Even the co‐oligopeptides with six or more residues, up to the dodecapeptide included, have given EI/MS. showing the molecular ion peak. The possible reasons for this uncommon behavior are examined.
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