Hydroalumination of Alkenes and Alkynes by Primary Aluminum Hydrides under Mild Conditions
Bibliographic record
Abstract
The reactions of the sterically crowded primary alane (Ar Pr i 8 AlH 2 ) 2 (Ar Pr i 8 = C 6 H-2,6(C 6 H 2 -2,4,6-Pr i 3 ) 2 -3,5-Pr i 2 ) with alkynes and alkenes are described. It is shown that hydroalumination of the terminal alkynes HCCSiMe 3 and HCCPh readily occurs under mild conditions via the cis -addition of the Al–H moiety across the CC triple bond with no evidence of hydrogen elimination. Hydroalumination was observed also with a range of terminal olefins, but no reactivity was observed with internal alkenes or alkynes. The relatively high reactivity of (Ar Pr i 8 AlH 2 ) 2 was attributed to the steric crowding of the large terphenyl substituent, which favors dissociation of the alane and increases the availability of the more reactive three-coordinate aluminum site in the monomer. In keeping with this view, studies of the reactions of the three primary alanes (Ar Pr i 8 AlH 2 ) 2, (Ar Pr i 4 AlH 2 ) 2 (Ar Pr i 4 = C 6 H 3 -2,6(C 6 H 3 -2,6-Pr i 2 ) 2 ), and (Ar Me 6 AlH 2 ) 2 (Ar Me 6 = C 6 H 3 -2,6(C 6 H 2 -2,4,6-Me 3 ) 2 ) with alkenes showed that the reaction rates are inversely proportional to the size of the terphenyl substituent, consistent with higher reactivity of the aluminum monomer. The structures of the alkenyl insertion products, Ar Pr i 8 Al(CHCHPh) 2 and Ar Pr i 8 Al(CHCHSiMe 3 ) 2, the alkylated derivative, Ar Pr i 8 Al(CH 2 CH 2 SiMe 3 ) 2, and the precursor aluminates {Li(OEt 2 )H 3 AlAr Pr i 8 ·Li(OEt 2 ) 2 H 3 AlAr Pr i 8 }, (LiH 3 AlAr Pr i 8 ) 2, and alanes (Ar Pr i 8 AlH 2 ) 2, and (Ar Pr i 4 AlH 2 ) 2 were determined by X-ray crystallography.
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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) | 0.002 | 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".