Synthesis of proline-valine pseudodipeptide enol lactones, serine protease inhibitors

A Convenient Synthesis of 1‐Deoxy‐8a‐epi‐Castanospermine Diastereoisomers (6R,7R,8S,8aS)‐6,7,8‐Trihydroxyindolizidine and (6R,7R,8R,8aS)‐6,7,8‐Trihydroxyindolizidine

“…Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin lu, Shanghai, 200032, P. R. China ment with BH 3 ·Me 2 S to afford the alcohol 5 in 99% yield, which was followed by Swern oxidation according to a literature procedure [9] to give aldehyde 6 in 95% yield. The addition of ethyl propiolate to aldehyde 6 using nBuLi as base in THF at Ϫ78°C [10] afforded a separable mixture of 7a and 7b in a combined yield of 80% (Scheme 3).…”

“…All solvents were refluxed and distilled from sodium benzophenone ketyl ( (5) and (S)-N-(tert-butoxycarbonyl)pyrrolidine-2-carboxaldehyde (6) were prepared according to a previously described procedure. [9] Compounds 7a and 7b: nBuLi (9.2 mL of a 2.0  solution in hexane, 18.5 mmol) was added slowly to a stirred solution of ethyl propiolate (1.88 mL, 1.814 g, 18.5 mmol) in dry THF (150 mL) at Ϫ78°C under Ar. The resulting solution was stirred at Ϫ78°C for 1 h. Then a solution of aldehyde 6 (1.844 g, 9.25 mmol) in dry THF (10 mL) was added through a cannula under positive Ar pressure.…”

Functionalized N‐aryl azetidinones as novel mechanism‐based inhibitors of neutrophil elastase

“…The ICso value (concentration or 3 that gives 50% inhibition 2 rain after mixing enzyme and inhibitor) was found equal to 0,01 mg/ml (a value or 0,01/~/ml was found for other monocyclic d.lactams [10]). HLE is inhibited less efficiently (factor of 3,4) by 3 than by a bromo enol lactone [24] but this reagent also inhibits chymotrypsin. Interestingly, the inhibitor 3 does not show significant efficiency to inhibit chymotrypsin, trypsin, plasmin and thrombin ( [I] …”

Short and stereodivergent syntheses of (−)-5-epi-tashiromine and (−)-tashiromine and the formal synthesis of (−)-isoretronecanol and (−)-trachelanthamidine

“…Data for 16a: (1.03 g, 79%); [a] D 25 = À28. 7,28.4,31.5,37.2,42.8,58.9,71.6,72.9,127.4,128.2,128.6,138.4,154.8. Anal.…”