Further progress towards enantioselective total synthesis of the bisbenzyltetrahydroisoquinoline alkaloid (-)-cycleanine
Bibliographic record
Abstract
Bisbenzylisoquinoline (BBIQ) alkaloids are a large group of compounds which outnumber those of most of the other alkaloid families. These compounds occur in many different plants and usually display a variety of pharmacological properties such as antitumor and antibacterial activities. The two benzylisoquinoline subunits in BBIQs can be connected through an oxygen atom or by carbon-carbon linkage. The subunits may have the same or opposite configurations at their asymmetric centres. BBIQs may also contain dihydroisoquinoline or tetrahydroisoquinoline units. A vast number of possible structures may be constructed in this way which make BBIQs very interesting synthetic targets. -- In this thesis, the asymmetric synthesis of the BBIQ (-)-cycleanine was attempted. A chiral auxiliary-assisted diastereoselective Bischler-Napieralski cyclization was used to form the two correct tetrahydroisoquinoline subunits. Two different methods of recently reported improved Ullmann coupling methods, namely (a) N,N-dimethylglycine promoted coupling, and (b) 2,2,6,6-tetramethylheptane-3,5-dione-accelerated coupling were first employed to build the framework of the target molecule. The use of a methodology of using a mild SNAr reaction between phenols and electron-deficient aryl fluorides was also evaluated. In addition, some efforts at making some intermediates for the total synthesis more synthetically accessible are also discussed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".