η<sup>5</sup>-Cyclopentadienyl-η<sup>3</sup>-1-phenylallylpalladium, an Unusually Effective Catalyst Precursor for Copper-Free and Copper-Assisted Sonogashira Cross-Coupling Reactions Catalyzed by Bis-phosphine Palladium(0) Compounds: The Role of Bis-acetylide Intermediates in the Reduction of a Palladium(II) Catalyst Precursor to a Palladium(0) Catalyst
Bibliographic record
Abstract
It has been demonstrated previously that Pd(η 3 -1-PhC 3 H 4 )(η 5 -C 5 H 5 ) ( I ) reacts with a number of phosphines L to form two-coordinate, zerovalent species of the type PdL 2, known to be effective cross-coupling catalysts for Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. Formation of PdL 2 from I is generally rapid and near quantitative, and I has therefore been found to be much more effective than more commonly utilized precursors such as Pd(PPh 3 ) 4, Pd 2 (dba) 3, and Pd(OAc) 2, which do not efficiently generate PdL 2 . This advantage is expected to apply as well to Sonogashira cross-coupling reactions, which are also believed to be catalyzed by species of the type PdL 2, and it is shown that the I /2PPh 3 catalyst system is much more active for the representative, conventional coupling reaction of bromobenzene with phenyl acetylene to form diphenylacetylene than are conventional catalyst systems based on Pd(PPh 3 ) 4, trans -PdCl 2 (PPh 3 ) 2, Pd 2 (dba) 3 /PPh 3, and Pd(OAc) 2 /PPh 3, the latter two activated with appropriate amounts of PPh 3 . Complementary studies involving the use of PBu t 3 with I, which generates an extremely active catalyst system, and the involvement of the cocatalyst CuI are also described, as is the catalytic competence of trans -Pd(C 2 Ph) 2 (PPh 3 ) 2, long considered to be an intermediate in the activation of trans -PdCl 2 (PPh 3 ) 2 but not heretofore, to our knowledge, shown to be viable.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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; both teacher heads agree on what is shown here.
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".