Addition of Enamines or Pyrroles and B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> “Frustrated Lewis Pairs” to Alkynes
Bibliographic record
Abstract
Reaction of 1-morpholinocyclohexene with B(C 6 F 5 ) 3 and phenylacetylene gave a mixture of two compounds, [C 6 H 10 N(CH 2 CH 2 ) 2 O][PhCCB(C 6 F 5 ) 3 ] ( 1a ) and C 6 H 9 (2-PhC═C(H)B(C 6 F 5 ) 3 )(N(CH 2 CH 2 ) 2 O ( 1b ). The analogous reaction with ethynylferrocene resulted in only the deprotonation product, the alkynyl-borate salt [C 6 H 10 N(CH 2 CH 2 ) 2 O][CpFe(C 5 H 4 )CCB(C 6 F 5 ) 3 ] ( 2 ). The related reactions of pyrrole, phenylacetylene, and B(C 6 F 5 ) 3 led to the vinyl-borate addition product, HNC 4 H 4 (2-PhC═C(H)B(C 6 F 5 ) 3 ) ( 3 ). In a similar fashion, reaction of N -methylpyrrole, phenylacetylene, and B(C 6 F 5 ) 3 gave a 3:2 ratio of the products MeNC 4 H 4 (2-PhC═C(H)B(C 6 F 5 ) 3 ) ( 4a ) and MeNC 4 H 4 (3-PhC═C(H)B(C 6 F 5 ) 3 ) ( 4b ), while the corresponding reaction of N - tert -butylpyrrole with phenylacetylene and B(C 6 F 5 ) 3 provided a single product, t BuNC 4 H 4 (3-PhC═C(H)B(C 6 F 5 ) 3 ) ( 5a ). Variations in the aryl alkynes produced the corresponding addition complexes, t BuNC 4 H 4 (3-ArC═C(H)B(C 6 F 5 ) 3 ) (Ar = p -C 6 H 4 Br 5b, m -C 6 H 4 Cl 5c, p -C 6 H 4 CF 3 5d, CpFe(C 5 H 4 ) 5e ). Similarly MeNC 4 H 2 (2,5-Me 2 )(3-ArC═C(H)B(C 6 F 5 ) 3 ) (Ar = Ph 6a, p -C 6 H 4 Br 6b, m -C 6 H 4 Cl 6c, p -C 6 H 4 CF 3 6d, CpFe(C 5 H 4 ) 6e ) were derived from 1,2,5-trimethylpyrrole. The species 5a and 5b were shown to rearrange to give t BuNC 4 H 3 (3-ArC═C(H)(C 6 F 5 )B(C 6 F 5 ) 2 ) (Ar = Ph 7a, CpFe(C 5 H 4 ) 7b ). The related complexes RNC 4 H 3 (3-PhC═C(H)(C 6 F 5 )B(C 6 F 5 ) 2 ) (R = SiMe 3 8, Ph 9 ) and MeNC 4 H(2,5-Me 2 )(3-PhC═C(H)(C 6 F 5 )B(C 6 F 5 ) 2 ) ( 10 ) were derived directly from the corresponding reactions of the pyrrole, PhCCH, and B(C 6 F 5 ) 3 . In the case of the reaction of N-tert -butylpyrrole, phenylacetylene, and PhB(C 6 F 5 ) 2, phenyl group migration was observed, affording exclusively the species t BuNC 4 H 3 (3-PhC═C(H)(Ph)B(C 6 F 5 ) 2 ) ( 11 ). Reaction of 5a or 4a/4b and t Bu 3 P resulted in deprotonation and formation of the salts [ t Bu 3 PH][RNC 4 H 3 ( X -PhC═C(H)B(C 6 F 5 ) 3 )] (R = t Bu, X = 3 12; R = Me X = 2 13a, 3 13b ). Reaction of 5a − d or 6a − d with one equivalent of Et 3 PO mediated proton transfer to generate a series of vinyl pyrroles t BuNC 4 H 3 (3-ArC═CH 2 ) (Ar = Ph 14a, p -C 6 H 4 Br 14b, m -C 6 H 4 Cl 14c, p- C 6 H 4 CF 3 14d ) and MeNC 4 H 2 (2,5-Me 2 )(3-ArC═CH 3 ) (Ar = Ph 15a, p -C 6 H 4 Br 15b, m -C 6 H 4 Cl 15c, p -C 6 H 4 CF 3 15d ) and the byproduct Et 3 PO·B(C 6 F 5 ) 3 .
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 machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.003 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".