Matches in SemOpenAlex for { <https://semopenalex.org/work/W852156772> ?p ?o ?g. }
Showing items 1 to 67 of
67
with 100 items per page.
- W852156772 abstract " The cytochalasans, a group of biologically active secondary metabolites isolated from micro-organisms, are tricyclic compounds which comprise of a heavily oxygenated 11-, 13- or 14-membered ring trans -fused to a substituted 8-azabicyclo [4.3.0]nonane ring system. One approach to the total synthesis of the cytochalasans involves the intramolecular Diels-Alder cyclization of a suitable 3-substituted- Δ 3 - pyrrolin-2-one. As preliminary work, a synthetic route to 5S-1-acyl-5- benzyl-3-butyl- Δ 3 -pyrrolin-2-ones was developed, starting from the known lactam, 5R-5-benzylpyrrolidin-2-one. However, although these dienophiles reacted stereospecifically with 2E,4E-hexadiene, the reaction conditions were harsh (200°, 30-50 h) and the sequence suffered from low overall yields. The doubly activated dienophile, 5S-1-benzoyl-5-benzyl-3-(1-oxopropyl)- Δ 3 -pyrrolin-2-one, on the other hand, was available via an expeditious route from the N -protected lactam, 5R-5-benzyl-1-( tert -butyldimethylsilyl)pyrrolidin- 2-one. Moreover, the dienophile reacted stereoselectively with 2E,4Ehexadiene under milder conditions (100°, 8 h) to give, after deprotection, 7-benzyl-2,5-dimethyl-1-(1-oxopropyl)-8-azabicyclo[ 4.3.0] non-3-en-9-one. The stereochemistry of the isoindolone adduct was shown to be the same as in naturally occurring cytochalasans. The overall yield from 5R-5-benzylpyrrolidin- 2-one after seven steps was 16%. In comparative studies, the doubly activated dienophile 1-benzenesulphonyl- 3-(1-oxopropyl)- Δ 3 -pyrrolin-2-one was prepared and its reactions with 2E,4E-hexadiene and cyclopentadiene were studied. Although the stereoselectivity was better than for the N -benzoylated pyrrolin-2-one, isolated yields of cycloadducts were inferior. Thus,as a model for ah approach to the [13]cytochalasans, the dienedienophile, 5S ,12E,14E-1-benzoyl-5-benzyl-3-(1-oxohexadeca-12,14-dienyl)- Δ 3 -pyrrolin-2-one, was prepared in 20% overall yield from 5R-5-benzylpyrrolidin- 2-one. Regio- and stereoselective cyclization was achieved under high pressure conditions (11-13 kbar) to give a tricyclic compound in 16-35% yield. The stereochemistry of the deprotected major adduct was shown to be that required for cytochalasan synthesis. Thus, the intramolecular Diels- Alder approach to cytochalasan synthesis using diene-lactams was validated." @default.
- W852156772 created "2016-06-24" @default.
- W852156772 creator A5090316388 @default.
- W852156772 date "1983-01-01" @default.
- W852156772 modified "2023-09-23" @default.
- W852156772 title "An approach to the synthesis of the cytochalasans" @default.
- W852156772 hasPublicationYear "1983" @default.
- W852156772 type Work @default.
- W852156772 sameAs 852156772 @default.
- W852156772 citedByCount "0" @default.
- W852156772 crossrefType "dissertation" @default.
- W852156772 hasAuthorship W852156772A5090316388 @default.
- W852156772 hasConcept C108204754 @default.
- W852156772 hasConcept C134121241 @default.
- W852156772 hasConcept C161790260 @default.
- W852156772 hasConcept C178790620 @default.
- W852156772 hasConcept C185592680 @default.
- W852156772 hasConcept C191897082 @default.
- W852156772 hasConcept C192562407 @default.
- W852156772 hasConcept C24961977 @default.
- W852156772 hasConcept C2776131168 @default.
- W852156772 hasConcept C2778176622 @default.
- W852156772 hasConcept C2780378348 @default.
- W852156772 hasConcept C35753019 @default.
- W852156772 hasConcept C71240020 @default.
- W852156772 hasConcept C75079739 @default.
- W852156772 hasConceptScore W852156772C108204754 @default.
- W852156772 hasConceptScore W852156772C134121241 @default.
- W852156772 hasConceptScore W852156772C161790260 @default.
- W852156772 hasConceptScore W852156772C178790620 @default.
- W852156772 hasConceptScore W852156772C185592680 @default.
- W852156772 hasConceptScore W852156772C191897082 @default.
- W852156772 hasConceptScore W852156772C192562407 @default.
- W852156772 hasConceptScore W852156772C24961977 @default.
- W852156772 hasConceptScore W852156772C2776131168 @default.
- W852156772 hasConceptScore W852156772C2778176622 @default.
- W852156772 hasConceptScore W852156772C2780378348 @default.
- W852156772 hasConceptScore W852156772C35753019 @default.
- W852156772 hasConceptScore W852156772C71240020 @default.
- W852156772 hasConceptScore W852156772C75079739 @default.
- W852156772 hasLocation W8521567721 @default.
- W852156772 hasOpenAccess W852156772 @default.
- W852156772 hasPrimaryLocation W8521567721 @default.
- W852156772 hasRelatedWork W1955814577 @default.
- W852156772 hasRelatedWork W1973974787 @default.
- W852156772 hasRelatedWork W1975706513 @default.
- W852156772 hasRelatedWork W1990010430 @default.
- W852156772 hasRelatedWork W2000703876 @default.
- W852156772 hasRelatedWork W2016154340 @default.
- W852156772 hasRelatedWork W2029043397 @default.
- W852156772 hasRelatedWork W2036308014 @default.
- W852156772 hasRelatedWork W2147924397 @default.
- W852156772 hasRelatedWork W2167346217 @default.
- W852156772 hasRelatedWork W2169697237 @default.
- W852156772 hasRelatedWork W2316997988 @default.
- W852156772 hasRelatedWork W2336555765 @default.
- W852156772 hasRelatedWork W2610307772 @default.
- W852156772 hasRelatedWork W2950517142 @default.
- W852156772 hasRelatedWork W2951566146 @default.
- W852156772 hasRelatedWork W2951811624 @default.
- W852156772 hasRelatedWork W2953322884 @default.
- W852156772 hasRelatedWork W3010912799 @default.
- W852156772 hasRelatedWork W2176104305 @default.
- W852156772 isParatext "false" @default.
- W852156772 isRetracted "false" @default.
- W852156772 magId "852156772" @default.
- W852156772 workType "dissertation" @default.