Inverse electron demand Diels-Alder reactions of coumarin-fused electron deficient dienes
Bibliographic record
Abstract
The Diels-Alder reaction is one of most powerful reactions for the construction of six-membered rings. As compared with the normal Diels-Alder reaction (HOMOdiene-LUMOdienophile), the inverse electron demand Diels-Alder (IEDDA) reaction (HOMOdienophile-LUMOdiene) has been explored to a far lesser extent. The synthesis of electron deficient dienes for IEDDA reactions is one of the major challenges in the development of IEDDA reactions. This thesis deals mainly with the exploration and applications of electron deficient coumarin-fused dienes in the IEDDA reactions. -- For the study of electron deficient coumarin-fused 2-azadienes, various 3-aminocoumarins were desired. In Chapter 1, a convenient synthesis of 3-aminocoumarins is described. A few azadienes were synthesized by the condensation of some of the 3-aminocoumarins and salicylaldehyde derivatives. These dienes were used in a study of proton-coupled electron transfer process in collaboration with Dr. D. W. Thompson. -- A multicomponent synthesis of l,2,3,4-tetrahydropyrido[2,3-c]coumarins, which involves an IEDDA reaction, was developed. Various in situ-generated coumarin-fused 2-azadienes react with electron rich dienophiles in the presence of Yb(OTf)₃ to afford, after IEDDA reaction and tautomerization of the initial adduct, 1,2,3,4-tetrahydropyrido[2,3-c]coumarins. Some aspects of the chemistry of these products were investigated. This discussion is covered in Chapter 2. -- Chapter 3 includes details of an exploratory study of intramolecular IEDDA reaction of the coumarin-fused 2-azadienes and its application to diversity-oriented synthesis of complex pentacyclic heterocycles. This reaction generally proceeds with very high diastereoselectivity in favor of the diastereomer arising from an exo transition state. -- Efforts toward the synthesis of a structurally interesting naphtho-fused [7]helicene are discussed in Chapter 4. A synthetic route to some key intermediates for this target has been established. -- In Chapter 5, an iterative strategy for the synthesis of a coum[5]isophenacene, a novel structural motif, is described. Some groundwork for future studies has been accomplished during these efforts.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".