Notice bibliographique
Résumé
This thesis, entitled "The use of camphor in sesquiter-penoid synthesis", consists of three chapters. Chapter One describes the conversion of (+)-8-bromocamphor (42) into a chiral dimethyl-acetal enolsilyl ether (105) that undergoes facile TiCl₄₋ promoted intramolecular cyclisation to provide tricyclic intermediates (195a,b), which after a series of functional group interconversions and the introduction of the gem-dimethyl group, leads to the first enantiospecific total synthesis of (+)-longiborneol (59) (ca. 13% in 21 steps from ( + )-camphor (26)). Oxidation of (+)-longiborneol (59) provides (+)-longicamphor (83), which was converted into (+)-longi-isoborneol (89) by reduction. Subsequent treatment with of (+)-longiisoborneol (89) with MsCl, 4-DMAP, and pyridine, reveals (+)-longifolene (61) (ca. 52% in 3 steps from (59)). Two other major attempts were also carried out prior to the successful synthesis of (59) and (61). Triene acetates (103a,b) were synthesised (ca. 8% in 10 steps from (+)-camphor (26)), but failed to undergo the intramolecular Diels-Alder reaction. In addition, (+)-campherenone (151) was also prepared (ca. 28% in 9 steps from (+)-camphor (26)), and both (151) and its derivatives (170), and (104) undergo SnCl₄-promoted intermolecular tertiary ∝-alkylation reaction to provide dimers (169a,b). Chapter Two describes two synthetic approaches to albene (221) which involves an intramolecular ene reaction, or an intramolecular free radical cyclisation reaction. A new enantiospecific synthesis route to (+)-β-santalene (259) (ca. 78% in 2 steps from (+)-campherenone (151)) is illustrated, however, (+)-β-santalene failed to undergo the intramolecular ene reaction to provide olefin (261). In addition, bromo-olefin (260) is also prepared (ca. 59% in 14 steps from (+)-camphor (26)), but cyclises in a 6-exo-trig mode in the intramolecular free radical cyclisation reaction to provide methyl ether (331). Chapter Three describes an evaluation of the potential use of (+)-5,6-dehydrocamphor (323) as a chiral synthon in the synthesis of the A,B ring system (cf. 329) of several classes of terpenoid. (+)-5,6-dehydrocamphor (323) was prepared from (-)-endo-3-bromocamphor (41) in two steps, and which is then converted to bicyclic enones (368a,b, 369a,b, 376a,b) by a sequence in which the key reaction was an anionic oxy-Cope rearrangement. Bicyclic enones (368a,b) were converted to tricyclic ketals (385a,b), but attempts to convert this compound to an angularly methylated intermediate (434) were unsuccessful. Furthermore, 1,5-dienols (409a,b), synthesised from (323) in ca. 50% yield, failed to undergo an anionic oxy-Cope rearrangement to provide bicyclic ketones (410a,b). Alternative ways of constructing an angular methyl group into the C(10) position in bicyclic enones (369a,b, or 376a,b) are currently being investigated in our laboratory. In addition, bicyclic ketones (373a,b) could serve as key intermediates in an enantiospecific synthesis of spirodysin (421), and indirectly to the synthesis of furodysin (422), and furodysinin (423). [Formula Omitted]
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».