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Enantioselective Construction of Alkylated Centers

2011· book-chapter· en· W3099818760 on OpenAlexaboutno aff
Douglass Taber

Bibliographic record

VenueOxford University Press eBooks · 2011
Typebook-chapter
Languageen
FieldChemistry
TopicAsymmetric Hydrogenation and Catalysis
Canadian institutionsnot available
Fundersnot available
KeywordsEnantioselective synthesisChemistryAlkylationStereocenterConjugateCatalysisAldehydeMedicinal chemistryOrganic chemistryCombinatorial chemistry

Abstract

fetched live from OpenAlex

Unsaturated half acid esters such as 1 are readily prepared by Stobbe condensation between dialkyl succinate and an aldehyde. Johannes G. de Vries of DSM and Floris P. J. T. Rutjes of Radboud University Nijmegen observed (Adv. Synth. Catal. 2008, 350, 85) that these acids were excellent substrates for enantioselective hydrogenation. Kazuaki Kudo of the University of Tokyo designed (Organic Lett. 2008, 10, 2035) a resin bound peptide catalyst for the transfer reduction of unsaturated aldehydes such as 3 , using 4 as the net H2 donor. Note that 5 was produced with high enantiocontrol from 3 that was a ~ 2:1 mixture of geometric isomers. Motomu Kanai and Masakatsu Shibasaki of the University of Tokyo devised (J. Am. Chem. Soc. 2008, 130, 6072) a chiral Gd catalyst that mediated the conjugate cyanation of enones such as 6 with high ee. Eric N. Jacobsen of Harvard University prepared (Angew. Chem. Int. Ed. 2008, 47, 1762) a dimeric Al salen catalyst that showed improved activity over the monomeric catalysts. Even congested imides such as 8 could be cyanated efficiently, delivering alkylated quaternary stereogenic centers. Takahiro Nishimura and Tamio Hayashi of Kyoto University optimized (J. Am. Chem. Soc. 2008, 130, 1576) the Rh*-catalyzed enantioselective conjugate addition of silyl acetylenes to enones such as 10, to give 12. Adriaan J. Minnaard and Ben L. Feringa of the University of Groningen devised (Angew. Chem. Int. Ed. 2008, 47, 398) conditions for the enantioselective 1,6-conjugate addition of alkyl Grignard reagents to diene esters such as the inexpensive ethyl sorbate 14. The product 16 incorporated, in addition to the newly formed stereogenic center, a geometrically defined E alkene. William S. Bechara and André B. Charette of the Université de Montréal found (Organic Lett. 2008, 10, 2315) that alkyl Grignard reagents could be induced to add with high enantioselectivity to pyridyl sulfones such as 17. In a different approach, Gregory C. Fu of MIT developed (J. Am. Chem. Soc. 2008, 130, 3302; J. Am. Chem. Soc. 2008, 130, 2756) conditions for the enantioselective alkenylation of racemic bromo esters such as 19, The latter reference is to the analogous enantioselective coupling of organozinc bromides with racemic allylic chlorides.

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 imitation

Not 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.

metaresearch head score (Codex)0.000
metaresearch head score (Gemma)0.000
Version: metacan-v3-hybrid-931329e0061cValidation status: machine_predicted_unvalidated
Candidate categoriesnone
Consensus categoriesnone
DomainCandidate signal: none · Consensus signal: none
Study designCandidate signal: Bench or experimental · Consensus signal: Bench or experimental
GenreCandidate signal: Empirical · Consensus signal: Empirical
Teacher disagreement score0.002
Threshold uncertainty score0.007

Distilled classifier scores by category (both heads)

CategoryCodexGemma
Metaresearch0.0000.000
Meta-epidemiology (narrow)0.0010.000
Meta-epidemiology (broad)0.0000.000
Bibliometrics0.0000.000
Science and technology studies0.0000.000
Scholarly communication0.0000.000
Open science0.0010.001
Research integrity0.0000.001
Insufficient payload (model declined to judge)0.0020.002

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.

Opus teacher head0.016
GPT teacher head0.180
Teacher spread0.165 · how far apart the two teachers sit on this one work
Validation statusscore_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it

Classification

machine, unvalidated

Machine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.

The models applied no category: nothing in the taxonomy fit this work.
Study designBench or experimental
Domainnot available
GenreEmpirical

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".

Quick stats

Citations0
Published2011
Admission routes1
Has abstractyes

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