Deprotonation and Addition Reactions of Frustrated Lewis Pairs with Alkynes
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Bibliographic record
Abstract
Deprotonation of terminal alkynes is effected by the treatment with t Bu 3 P and B(C 6 F 5 ) 3 to give [ t Bu 3 PH][PhCCB(C 6 F 5 ) 3 ] ( 1a ) and [ t Bu 3 PH][RCCB(C 6 F 5 ) 3 ] (R = n Bu 2, t Bu 3, Me 3 Si 4, and CpFe(C 5 H 4 ) 5 ). In a similar fashion, FLP deprotonation of 1,4-diethynylbenzene was employed to prepare the salt [ t Bu 3 PH] 2 [(C 6 F 5 ) 3 BCC(C 6 H 4 )CCB(C 6 F 5 ) 3 ] ( 6 ). As well, use of differing Lewis acids afforded the species [ t Bu 3 PH][PhCCEAr 3 ] (EAr 3 = Al(C 6 F 5 ) 3 7, PhB(C 6 F 5 ) 2 8, BPh 3 9 ). The corresponding reaction of Me 3 SiCCSiMe 3 afforded [ t Bu 3 PSiMe 3 ][Me 3 SiCCB(C 6 F 5 ) 3 ] ( 10 ). For less basic phosphines, phosphine/borane addition reactions were observed with alkynes. Thus the species E -R 3 P(Ph)C═C(H)B(C 6 F 5 ) 3 (R = o -tol 11, Ph 12 ) were prepared. In the latter case, Ph 3 P·B(C 6 F 5 ) 3 was employed. Similarly, E -Ph 3 P(CpFe(C 5 H 4 ))C═C(H)B(C 6 F 5 ) 3 ( 13 ), E -Ph 3 P(Ph)C═C(Me)B(C 6 F 5 ) 3 ( 14 ), E -R 2 PH(Ph)C═C(H)B(C 6 F 5 ) 3 (R = Ph 15, C 6 H 2 Me 3 16 ), and E -(C 6 H 2 t Bu 3 )PH 2 (Ph)C═C(H)B(C 6 F 5 ) 3 ( 17 ) were prepared. Again, variation in the Lewis acid afforded E -Ph 3 P(Ph)C═C(H)EAr 3 (EAr 3 = PhB(C 6 F 5 ) 2 18, Al(C 6 F 5 ) 3 19 ), E -Ph 3 P( n Bu)C═C(H)Al(C 6 F 5 ) 3 ( 20 ), and E -( o -tol) 3 P(Ph)C═C(H)Al(C 6 F 5 ) 3 ( 21 ). The macrocyclic [(H)C═C(Ph)Mes 2 PC 6 F 4 B(C 6 F 5 ) 2 ] 2 ( 22 ) was prepared from the analogous alkyne addition to Mes 2 PC 6 F 4 B(C 6 F 5 ) 2, while E -Ph 2 PCH 2 CH 2 PPh 2 (Ph)C═C(H)B(C 6 F 5 ) 3 ( 23 ) and E -(CH 2 PPh 2 (Ph)C═C(H)B(C 6 F 5 ) 3 ) 2 ( 24 ) were derived from the reactions of Ph 2 PCH 2 CH 2 PPh 2 . The related addition reaction involving 1,4-diethynylbenzene gave E -HC≡CC 6 H 4 C(PPh 3 )═C(H)B(C 6 F 5 ) 3 ( 25 ), while subsequent reaction with t Bu 3 P and B(C 6 F 5 ) 3 yielded the unusual salt/zwitterion [ t Bu 3 PH][(C 6 F 5 ) 3 BCC≡C 6 H 4 C(PPh 3 )═C(H)-B(C 6 F 5 ) 3 ] ( 26 ). Reaction of PhCH 2 NMe 2 with PhCCH and B(C 6 F 5 ) 3 gave give a 84:16 mixture of [PhCH 2 NMe 2 H][PhCCB(C 6 F 5 ) 3 ] ( 27a ) and PhCH 2 NMe 2 (Ph)C═C(H)B(C 6 F 5 ) 3 ( 27b ), while imines were used to prepare [( t Bu)HN═CHPh][PhCCB(C 6 F 5 ) 3 ] ( 28 ) and [( t Bu)HN═CPh 2 ][PhCCB(C 6 F 5 ) 3 ] ( 29 ). The corresponding reaction of t BuNCN t Bu, B(C 6 F 5 ) 3, and two equivalents of PhCCH led to the unusual product [ t BuNCN(H)C(Ph)═C(H) t Bu][PhCCB(C 6 F 5 ) 3 ] ( 30 ). Finally, non-pnictogen Lewis bases were explored. The reaction of the N-heterocyclic carbene I t Bu with B(C 6 F 5 ) 3 and PhCCH was shown to yield the deprotonation product [I t BuH][PhCCB(C 6 F 5 ) 3 ] ( 31 ), while the sulfides R 2 S gave E -R 2 S(Ph)C═C(H)B(C 6 F 5 ) 3 (R = Me 32, PhCH 2 33 ). The formation of these latter sulfide zwitterions was demonstrated to be reversible.
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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) | 0.008 | 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 it