Química Orgânica 2 · Synthesis planning
Rotas de síntese: reagentes, grupos protetores e planejamento em várias etapas: problemas de prática
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Comece a desenhar: Rotas de síntese: reagentes, grupos protetores e planejamento em várias etapas
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- Acetonide protection of propane-1,2-diol with 2,2-dimethoxypropane
- BBr₃ removes the methyl group from 4-methylanisole
- Boc protection of 4-aminobutan-1-ol with Boc₂O
- DMAP-catalysed acetylation of 2-phenylethanol
- Cyclohexylmagnesium bromide and formaldehyde give cyclohexylmethanol
- Acid hydrolysis of 2-methyl-2-phenyl-1,3-dioxolane releases acetophenone
- Acid-catalysed hydration of pentanenitrile to pentanamide
- tert-Butyl benzoate from benzoic acid and isobutylene
- Protected Grignard reagent plus acetone gives 5-hydroxy-5-methylhexanal
Desenhe o mecanismo 33
- Acetonide protection of propane-1,2-diol with 2,2-dimethoxypropaneDraw the acid-catalysed transfer of the isopropylidene group from 2,2-dimethoxypropane to propane-1,2-diol, through two oxocarbenium ions and with loss of two methanol molecules, that closes the five-membered acetonide ring.
- BBr₃ removes the methyl group from 4-methylanisoleDraw the Lewis acid–base adduct of 4-methylanisole with boron tribromide, the bromide SN2 at the methyl carbon, and the aqueous workup that releases 4-methylphenol, the deprotection of a phenol methyl ether.
- Boc protection of 4-aminobutan-1-ol with Boc₂ODraw how the amine of 4-aminobutan-1-ol attacks di-tert-butyl dicarbonate, how the tetrahedral intermediate collapses, and how the leaving group breaks down to CO₂ and tert-butoxide, which removes the last N–H proton to give the Boc carbamate while the alcohol is left free.
- DMAP-catalysed acetylation of 2-phenylethanolDraw how 4-(dimethylamino)pyridine turns acetic anhydride into an N-acetylpyridinium ion, how 2-phenylethanol is acetylated by that ion, and how the catalyst is released to protect the alcohol as its acetate ester.
- Cyclohexylmagnesium bromide and formaldehyde give cyclohexylmethanolDraw the addition of cyclohexylmagnesium bromide to formaldehyde and the acidic workup, and recognise this as the way to lengthen a chain by one carbon ending in CH₂OH.
- Acid hydrolysis of 2-methyl-2-phenyl-1,3-dioxolane releases acetophenoneDraw the acid-catalysed hydrolysis that removes an ethylene ketal protecting group: ring opening to the oxocarbenium ion, capture by water, and loss of ethane-1,2-diol to give acetophenone.
- Acid-catalysed hydration of pentanenitrile to pentanamideDraw how aqueous acid adds water across the C≡N bond of pentanenitrile, through the nitrilium ion and the imidic acid, to give pentanamide, and recognise that mild conditions stop at the amide while prolonged heating in aqueous acid continues to pentanoic acid.
- tert-Butyl benzoate from benzoic acid and isobutyleneDraw the acid-catalysed addition of benzoic acid to 2-methylpropene through the tert-butyl cation, the way a carboxylic acid is protected as its tert-butyl ester.
- Protected Grignard reagent plus acetone gives 5-hydroxy-5-methylhexanalAdd a dioxolane-protected Grignard reagent to acetone, then unmask the aldehyde by acid hydrolysis of the acetal.
- Proteção do cis-ciclo-hexano-1,2-diol como acetonídeoProteja o cis-ciclo-hexano-1,2-diol como acetonídeo desenhando os dois íons oxocarbênio formados a partir do 2,2-dimetoxipropano e sua captura por cada OH.
- Propynide alkylation gives pent-2-yne, the Lindlar precursorBuild pent-2-yne from propyne by acetylide formation and SN2 with bromoethane, the first stage of a route to (Z)-pent-2-ene.
- Metilação do fenilacetileto: 1-fenilpropinoAumente o fenilacetileno em um carbono: desprotone com amideto de sódio e desenhe a SN2 do acetileto no iodometano até o 1-fenilpropino.
- Desmetilação do 2-metoxinaftaleno com BBr3: 2-naftolClive o éter metílico do 2-metoxinaftaleno com BBr3 desenhando o aduto O–B, a SN2 do brometo na metila e a hidrólise do ariloxiborano.
- Benzoic acid to methyl benzoate through benzoyl chlorideConvert benzoic acid to methyl benzoate by drawing acyl chloride formation with SOCl2 and its methanolysis.
- Proteção Boc da (S)-1-feniletilamina: carbamato BocProteja a (S)-1-feniletilamina com Boc2O, mostrando o grupo abandonador carbonato de terc-butila se decompondo em CO2 e o centro (S) inalterado.
- TFA removes the Boc group: benzylamineRemove a Boc group with TFA by drawing tert-butyl cation loss, its E1 to isobutylene and the decarboxylation of the carbamic acid.
- O TFA remove o grupo Boc da N-Boc-piperidina: piperidinaDesproteja a N-Boc-piperidina com TFA desenhando a perda do cátion terc-butila, a formação de isobutileno e a descarboxilação do ácido carbâmico.
- Cbz protection of benzylamine: benzyl benzylcarbamateProtect benzylamine as a Cbz carbamate by addition–elimination at benzyl chloroformate.
- Proteção Cbz da ciclo-hexilamina: carbamato de benzilaProteja a ciclo-hexilamina como carbamato Cbz desenhando a adição ao cloroformato de benzila, a perda de cloreto e a desprotonação pelo carbonato.
- Acetilação do (R)-1-feniletanol com DMAP: acetato (R)Acetile o (R)-1-feniletanol com Ac2O por meio do íon N-acetilpiridínio formado pelo DMAP, mantendo o centro (R).
- Piperidine removes the Fmoc group: benzylamineRemove an Fmoc group with piperidine by drawing fluorenyl deprotonation, E1cB loss of the carbamate and decarboxylation.
- A piperidina remove o Fmoc: ciclo-hexilaminaRemova um grupo Fmoc da ciclo-hexilamina desenhando a desprotonação do fluorenila, a perda do carbamato por E1cB e a descarboxilação.
- Brometo de fenilmagnésio e formaldeído: álcool benzílicoAcrescente um carbono a um anel benzênico desenhando a adição do brometo de fenilmagnésio ao formaldeído e o tratamento ácido até o álcool benzílico.
- Hidrólise do etilenocetal da ciclo-hexanona: ciclo-hexanonaRemova um grupo protetor etilenocetal com ácido aquoso, desenhando os dois íons oxocarbênio e cada transferência de próton até a ciclo-hexanona.
- MOM protection of benzyl alcohol: [(methoxymethoxy)methyl]benzeneProtect benzyl alcohol as a methoxymethyl ether by SN2 at the CH2 of MOMCl and amine deprotonation.
- Hidratação ácida da fenilacetonitrila: 2-fenilacetamidaHidrate a fenilacetonitrila a 2-fenilacetamida em ácido sulfúrico, desenhando o íon nitrílio, a adição de água e a tautomerização do ácido imídico.
- O TBAF remove o grupo TBS: 3-fenilpropan-1-olDesproteja um éter TBS com fluoreto e protone o alcóxido liberado para obter o 3-fenilpropan-1-ol.
- TBS protection of cyclohexanol: tert-butyldimethyl(cyclohexyloxy)silaneProtect cyclohexanol as its TBS ether by drawing substitution at silicon and the imidazole deprotonation.
- Proteção TBS do (R)-butan-2-ol: éter (R)-TBSProteja o (R)-butan-2-ol como éter TBS e mostre por que o estereocentro mantém a configuração (R).
- TBAF removes the TBS group: cyclohexanolRemove a TBS protecting group with fluoride and protonate the released cyclohexoxide.
- Éster terc-butílico do ácido fenilacético a partir do isobutilenoProteja o ácido fenilacético como éster terc-butílico desenhando o cátion terc-butila formado a partir do isobutileno e sua captura pelo ácido.
- THP protection of benzyl alcohol: 2-(benzyloxy)oxaneProtect benzyl alcohol as a THP acetal through an oxocarbenium ion formed from dihydropyran.
- Proteção THP do ciclo-hexanol: 2-(ciclo-hexilóxi)oxanoProteja o ciclo-hexanol como acetal THP protonando o di-hidropirano a um íon oxocarbênio e capturando-o com o álcool.
Preveja o produto 7
- Benzyl chloride to a one-carbon-longer acidPredict the carboxylic acid formed when a Grignard reagent is carboxylated with CO₂.
- Boc and Cbz on the same diaminePredict which of two carbamate protecting groups on the same molecule is removed by catalytic hydrogenolysis.
- A five-step road from bromobenzenePredict the product of a multistep sequence that adds a carbon and then converts it through acid, acid chloride and amide to an amine.
- Choosing the less substituted alkenePredict the major E2 product when a bulky base is used to make a less substituted alkene from a tertiary halide.
- Hydroboration–oxidation of hex-1-enePredict the anti-Markovnikov alcohol formed by hydroboration–oxidation of a terminal alkene.
- Ozonolysis of a ring alkenePredict the open-chain dicarbonyl compound formed when ozonolysis cleaves a C=C bond inside a ring.
- Follow a three-step sequencePredict the product of an oxidation, Grignard addition and E1 dehydration carried out in sequence.
Classificar 4
- Which aryl bromide needs no protection?Classify functional groups as compatible or incompatible with formation of a Grignard reagent.
- Which step needs an oxidant?Classify functional-group interconversions as oxidations, reductions or neither by comparing bonds to oxygen and hydrogen.
- Interconversão de grupo funcional vs desconexãoIdentifique qual seta retrossintética é uma interconversão de grupo funcional, e não uma desconexão.
- O que é um sínton na retrossíntese?Defina sínton e diferencie-o do reagente que serve como seu equivalente sintético.
Comparar 2
- Remove one protecting group, keep the otherCompare deprotection conditions to pick the reagent that removes a silyl ether while a benzyl ether stays.
- The one-carbon oxidation ladderRank one-carbon compounds by the oxidation state of carbon to see which interconversions need an oxidant or a reductant.
Calcular 5
- Convergent versus linearCalculate the overall yield of a convergent route along its longest linear sequence and compare it with a linear route.
- Count the carbons after an epoxide openingCount the carbons in the product of a Grignard reagent opening ethylene oxide.
- How much Grignard reagent?Count the equivalents of Grignard reagent consumed by an acidic O–H and an ester in the same molecule.
- Overall yield of a four-step routeCalculate the overall yield of a linear synthesis by multiplying the step yields.
- Rendimento global de uma síntese em três etapasCalcule o rendimento global de uma síntese linear em três etapas multiplicando os rendimentos de cada etapa.
Encontre o erro 4
- A protecting group that does not protectDiagnose why an ester protecting group fails in a Grignard step and choose a compatible alternative.
- A route that stallsDiagnose a failed aromatic synthesis caused by the Friedel–Crafts limitation and reorder the steps.
- Fix the route to trans-2-methylcyclohexanolDiagnose a regiochemical error in a proposed alkene hydration and replace it with the reagent that gives the required regio- and stereochemistry.
- Ordem errada: LiAlH4 depois da formação do ésterDiagnostique uma rota que forma um éster antes de uma redução com LiAlH4 e corrija-a reduzindo primeiro e esterificando por último.
Trabalhe de trás para frente 2
- Which ester makes 3-ethylpentan-3-ol?Work backwards from a tertiary alcohol with two identical groups to the ester that supplies the third group.
- Disconnect pentan-3-oneChoose a nitrile and Grignard reagent pair that gives a target ketone after acidic hydrolysis.
Planeje uma síntese 20
- Benzene to 3-bromoanilineOrder aromatic substitutions and a functional-group interconversion so that the directing effects give a meta-disubstituted product.
- Hex-1-yne to hexan-2-oneChoose the reagent that hydrates a terminal alkyne to a methyl ketone rather than an aldehyde.
- Benzoic acid to benzaldehydePlan a reduce-then-reoxidise sequence when no single common reagent stops at the needed oxidation level.
- But-1-yne to (Z)-hex-3-enePlan a C–C bond formation followed by a stereoselective alkyne reduction, in the right order, to reach a cis alkene.
- Acetylene to hex-3-ynePlan two sequential acetylide alkylations to place one ethyl group on each end of an alkyne.
- Reduce the ester, keep the ketoneOrder protection, reduction and deprotection steps so that a hydride reagent reduces only the less reactive carbonyl group.
- Markovnikov hydration without rearrangementChoose a hydration method that gives the Markovnikov alcohol of an alkene whose carbocation would rearrange.
- Butan-1-ol to butanalChoose the oxidant that converts a primary alcohol into an aldehyde without over-oxidation.
- 1-Bromobutane to hexan-1-olPlan a two-carbon chain extension that ends in a primary alcohol.
- 4-Aminophenol from phenolOrder nitration, separation and reduction to make 4-aminophenol.
- Da ciclo-hexanona à ciclo-hexilamina: duas rotasReconheça duas rotas válidas de uma cetona a uma amina primária: aminação redutiva em uma etapa e formação de oxima seguida de redução com LiAlH4.
- Oxidize one of two OHUse a selective protecting group to oxidise only a secondary alcohol in a diol.
- Aldehyde + bromide in same moleculeSequence protection, Grignard formation and deprotection for a bifunctional substrate.
- Amine during FCPlan protection of an aniline before Friedel–Crafts acylation.
- Mild oxidationChoose a chemoselective oxidant for an aldehyde in the presence of an alkene.
- trans-DiolChoose reagents for anti dihydroxylation of an alkene.
- Fix the alkene positionChoose a route that places a C=C at a defined position without isomer mixtures.
- 1,5-Dicarbonyl via MichaelChoose a C–C bond-forming reaction that builds a 1,5-dicarbonyl.
- +1 C to acidConvert an alkyl bromide into the carboxylic acid with one more carbon.
- Ketone from alkyneOrder the steps that build a methyl ketone from acetylene.
Explique por quê 3
- Why acetals are good ketone protecting groupsExplain why acetals survive basic and nucleophilic reagents but are removed by aqueous acid.
- Why acetylate aniline before nitrating?Explain why an amine is converted to an amide before electrophilic nitration in a route to a para-substituted aniline.
- Why acylate, then reduce?Explain why a straight-chain alkylbenzene is made by Friedel–Crafts acylation followed by carbonyl reduction.
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