Divergent Synthesis of 1,2,3,4‐Tetrasubstituted Cyclobutenes from a Common Scaffold: Enantioselective Desymmetrization by Dual‐Catalyzed Photoredox Cross‐Coupling
Bibliographic record
Abstract
Abstract Four‐membered carbocycles are important structural motifs found in several natural products and drugs. Amongst those, cyclobutenes are attractive intermediates because the residual olefin can be manipulated selectively into various saturated and unsaturated analogs. Few methods exist to access chiral tri‐ and tetra‐C‐substituted cyclobutenes and they are generally limited in terms of diversification. Herein, a divergent synthetic strategy was developed where a single optically enriched scaffold is diversified into a variety of derivatives with different substitution patterns. To this end, the enantioselective desymmetrization of prochiral 1,2‐dibromocyclobutene imides was enabled by a dual Ir/Ni‐catalyzed photoredox C(sp 2 )−C(sp 3 ) cross‐coupling with an alkyltrifluoroborate salt to install a convertible carbon fragment in good yields and >90 % enantiomeric excess. Exceptional mono‐coupling selectivity is observed and the resulting chiral bromocyclobutene serves as a common scaffold that can be transformed in a divergent manner into several valuable 1,2,3,4‐tetra‐C‐substituted cyclobutane products while maintaining optical purity.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".