Nucleoside und verwandte Verbindungen, VI. Synthese der anomeren 2′‐Desoxy‐D‐ribopyranosyl‐uracile

Abstract

Bis‐O‐trimethylsilyl‐uracil (3), das mit Methyljodid oder Acetylchlorid selektiv N‐1‐substituierte Uracile bildet, reagiert in Gegenwart verschiedener Katalysatoren bei niedrigen Temperaturen mit den 2‐Desoxy‐D‐ribopyranosylchloriden 7 und 8 in guten Ausbeuten zu den acylierten α,β‐Nucleosiden 11 (p‐Toluat) bzw. 12 (p‐Nitro‐benzoat). Nach Entacylierung und Säulenchromatographie werden daraus 2′‐Desoxy‐α‐D‐ribopyranosyl‐uracil (α‐13) und sein β‐Anomeres β‐13 gewonnen, wobei α‐13 gegenüber der β‐Form in jedem Falle überwiegt. Die O‐Silyl‐Verbindung von 4‐O‐Äthyl‐uracil (5) reagiert analog mit dem Halogenzucker 8 zu den p‐Nitro‐benzoaten der 2′‐Desoxy‐ribopyranosyl‐nucleoside von 4‐O‐Äthyl‐uracil (α,β‐14). Diese werden durch fraktionierte Kristallisation und Säulenchromatographie in die reinen Anomeren α‐14 und β‐14 getrennt. Die Struktur der Nucleoside wird durch UV‐ und ORD‐Spektren, bei 14 durch Entalkylierung und Entacylierung zu 13 bewiesen.

Steroid total synthesis. 11. (+)-Estr-4-ene-3,17-dione from a chiral lactone

“…In contrast, when heated at reflux in toluene with piperidinium acetate,15 20 gave a mixture of the two ketones 21 and 22 in approximately 70% yield. Exposure of isomer 22 to p-toluenesulfonic acid in toluene at reflux resulted in a 60% yield of the conjugated isomer 21. The physical data for compound 21 compare well with the reports in the literature;16 however, 22 could not be compared with previously synthesized material as no data are given,17 and the structure rests solely on our 7H NMR, IR, and UV spectra (see Experimental Section).…”

“…To a solution at 10 °C containing 4.68 g (9.3 mmol) of 1-O-acetyl-2,3,5-tri-O-benzoyl-d-D-ribofuranoside25 and 2.0 g (8.6 mmol) of bis(0-trimethylsilyl) [4-13C] uracil (10) in 100 mL of dry acetonitrile under a dry nitrogen atmosphere was added 1.6 g (6.1 mmol) of freshly distilled (from P2O5) stannic chloride in 50 mL of dry acetonitrile. The resulting solution was stirred at room temperature (22 °C) for 16 h and the solvent was removed at 22 °C under reduced pressure. The residue was dissolved in 300 mL of 1,2-dichloroethane and shaken with 250 mL of a saturated sodium bicarbonate solution.…”

“…Condensation of the amine Scheme I Scheme II (Scheme II), derived from this lactone, with 2-methylcyclopentane-l,3-dione gave predominantly the 13/3 trans diene 17, indicative of a highly diastereoselective process. Suitable manipulations of this key substrate 17 then generated the target compounds 21,22, and 27 (Scheme III).…”

Synthesis and pharmacology of 5-noralkyl-9.beta.-methyl-6,7-benzomorphans and stereochemistry of some intermediates

“…Smith and Cook have shown that apocodeine (2) may be Oand N-dealkylated in vivo by rats to 1 and norapomorphine. 16…”

“…By some modifications of this sequence we have now prepared the 2'-hydroxy relative 18. Described below are the synthesis of 18 and the analgetic and other pharmacologic properties of16 and 18 and two analogs, 15 and 17.…”