Synthetic used of alkali metals on charcoal and graphite: ketone alkylation

Hart, Harold; Chen, Binglin; Peng, C. T.

doi:10.1016/s0040-4039(01)83176-2

Cited by 19 publications

(3 citation statements)

References 11 publications

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“…The initial concentration in [3,3-*H2]1 in the experiments in the normal addition mode was somewhat lowered because [3,3-2H,]1 is somewhat less soluble than the substrate previously used. 20) The solution was homogeneous as judged visually.…”

Section: )mentioning

confidence: 98%

“…The ketyls disproportionate and the enolate ~-([3-~H]l) -K+ so formed is 27) We carried out the reductions at -35", and used a maximum of 4 mol-equiv. of potassium (run 20) rather than 5 in the runs with [3,3-2H2] 2.3.2) but in this case employing lithium, sodium, and potassium, in order to see whether the product distributions using potassium as the reducing agent and unlabeled or labeled substrate differ (see 2.2.4), and whether we could reproduce the results in the literature. Our results are collected in Table 4 .…”

Section: Procedures Of Coulombeaumentioning

confidence: 99%

“…The ketyls disproportionate and the enolate ~-([3-~H]l) -K+ so formed is 27) We carried out the reductions at -35", and used a maximum of 4 mol-equiv. of potassium (run 20) rather than 5 in the runs with [3,3-2H2]1 in order to not have to quench the excess of potassium, used 5 mol-equiv. in t h e p n s with 1 (run 23), and quenched with ethanol or ammonium chloride.…”

Section: Procedures Ofmentioning

confidence: 99%

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Alkali Metal/Ammonia Reductions of Ketones Should Be Run in the Presence of Ammonium Ion

Rautenstrauch

Willhalm

Thommen

et al. 1981

Helvetica Chimica Acta

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SummaryReduction of ( +)- [3,3-2H,]camphor ([3,3-,H2]1) with lithium, sodium or potassium in ammonia and a co-solvent gave: 1) the enolate of [3,3-2H2]1 and the alcoholates of (-)- [2,3,3-2H3]isoborneol ([2,3,3-2H3]2) and ( +)- [2,3,3-2H3]borneol ([2,3,HJ3); 2) the alcoholates of [3,3-2H,] [3,3-2H,]3) under certain conditions. Different values for these ratios were found in the reductions with each metal, all of which corresponded to low overall diastereoselectivities. Reactions 1 and 3 persisted when the reductions were carried out in ammonia/water/co-solvent mixtures and the enolate formed via reaction 1 was protonated and the resulting [end0-3-~H]1 recycled. Reaction 2 cannot be monitored under these conditions. Reactions 1 and 3, and by inference also reaction 2, were almost completely suppressed when analogous reductions were carried out in the presence of ammonium chloride, [3,3-,H2]2 and [3,3-2H,]3 being obtained almost exclusively, in a 6 :94 ratio, with all three metals. A parallel reduction of 1 afforded 2 and 3 in a 6 : 94 ratio. It is proposed that the mechanism outlined in House [l] was dominant when, and only when, ammonium ion was the proton source; it may have competed when water was the proton source.

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Section: )mentioning

confidence: 98%

Section: Procedures Of Coulombeaumentioning

confidence: 99%

“…The ketyls disproportionate and the enolate ~-([3-~H]l) -K+ so formed is 27) We carried out the reductions at -35", and used a maximum of 4 mol-equiv. of potassium (run 20) rather than 5 in the runs with [3,3-2H2]1 in order to not have to quench the excess of potassium, used 5 mol-equiv. in t h e p n s with 1 (run 23), and quenched with ethanol or ammonium chloride.…”

Section: Procedures Ofmentioning

confidence: 99%

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