Structure Elucidation of a New Icosapeptide from Human Semen

✍ Scribed by Dr. Klaus Schneider; Josef Reiner; Prof. Dr. Gerhard Spiteller

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 332 KB
• Volume: 26
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198707741

✦ Synopsis

reflux for 20 h and allowed to cool, and the nearly quantitatively precipitated dicyclohexylurea was filtered off and washed with a small amount of dichloromethane. The combined organic phases were concentrated in vacuum and the residue was dissolved in ether. The ether solution was washed with NaHCO, solution to a final pH of 7 and then dried over Na2SOI and concentrated once again. The crude 3 was purified by distillation (or by column chromatography). 4 : 3 (0.5 mol) was allowed to stir in 250 mL of methanol with 5 mL of 30% NaOCH, for 12 h. After concentration in vacuum, the residue was distilled without further workup.

Example-Neomenthyl.formate 3c:

The isourea ether 2c obtained from (-)menthol Ic (156 g, 1.0 mol) and dicyclohexylcarbodiimide (248 g, 1.2 mol) was allowed to stir with 45 mL (1.2 mol) of formic acid in 400 mL of dry toluene for 20 h at 1IO"C. The reaction mixture was then worked up according to the general procedure described above. After distillation, 147 g (80%) of 3c was obtained, b.p.=52-6O0C/0.25 mbar, [a]gl= +51.9" (neat) ([a]?= + 5 I 161).