Catalytic reduction of benzoate esters and lactones in the presence of PhMeSiH<sub>2</sub> and a titanocene-based catalyst
Bibliographic record
Abstract
PhMeSiH 2 reduces ethyl benzoate in the presence of a Cp 2 TiMe 2 (Cp = η 5 -cyclopentadienyl) catalyst to give PhMeSi(OEt)(OCH 2 Ph) (1). Small to moderate amounts of toluene are also produced, depending on the reaction conditions. Under 40 psi of H 2 the same reaction gives quantitative reduction of the ester to toluene. PhCHO is reduced, under the same conditions as the ester, to a mixture of PhMeSi(OCH 2 Ph) 2 and toluene in proportions similar to that observed with the ester. A stoichiometric reaction of PhMeSiH 2 , PhCOOEt, and Cp 2 TiMe 2 resulted in the formation of known [Cp 2 Ti(OEt)] 2 (2) in 75% isolated yield. A mechanism is proposed in which the C=O of the ester inserts into a TiH bond. A Ti-mediated transfer of the ethoxy group from the resulting (α-ethoxy)benzyloxytitanium intermediate to silicon produces PhMeSi(OEt)H and PhCHO. 1 is generated via hydrosilation of PhCHO by PhMeSi(OEt)H. Both β- and γ-butyrolactones react with PhMeSiH 2 in the presence of a catalytic amount of Cp 2 TiMe 2 to produce copolymers -[O-PhMeSi-O(CH 2 ) 3 CHR] n - (R = H, 3; R = Me, 4) (M w [Formula: see text] 1 × 10 3 ; M w /M n [Formula: see text] 1.3). A mechanism analogous to that proposed for the ethyl benzoate reduction is proposed. A reaction of PhMeSiH 2 and γ-butyrolactone with a stoichiometric amount of Cp 2 TiMe 2 in the presence of tetrahydofuran (THF) produces Cp 2 Ti(µ-H)(µ-η 1 ,η 5 -C 5 H 4 )Ti(OC 4 H 8 )Cp(5) (65% isolated yield) whose structure is determined by X-ray crystallography.Key words: hydrosilation, esters, lactones, titanocene, catalysis.
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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 | 0.000 |
| 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 | 0.000 |
| 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".