Bicyclo[1.1.1]pentane Ketones via Friedel–Crafts Acylation
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Bicyclo[1.1.1]pentane (BCP) is a rigid aliphatic hydrocarbon with a three-dimensional (3D), propeller-like shape and a molecular size that makes it a targeted bioisosteric replacement for phenylene and acetylene groups in medicinal chemistry. For the pharmaceutical application of BCP, simple, efficient, and cost-effective synthetic tools are required to enable the exploration of BCP’s potential as a bioisostere across a broad chemical space. With numerous sophisticated protocols for C(sp 3 ) functionalization of rigid aliphatic hydrocarbons reported in the literature, the synthesis of BCP mono- and diketones remains a challenging task, limited by both substrate scope and expensive photocatalysts. Here, we present a protocol for Friedel–Crafts acylation of (hetero)aromatic hydrocarbons with BCP acyl chlorides; in particular, the first method to access diaromatic BCP 1,3-diketones. Reaction optimization, substrate scope, and reactivity of the products are discussed. A total of 35 mono- and diketones are reported, accompanied by 7 examples of postsynthetic modifications. The synthesis of a BCP analogue of fenofibrate is reported. Noncovalent interactions of the compounds in the solid state are discussed, including a Hirshfeld analysis.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 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".