Química Orgânica 1 · Stereochemistry
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- OsO4 dihydroxylation of cyclopentene gives cis-cyclopentane-1,2-diol
- Anti addition of bromine to cis-2-butene gives the racemic dibromide
- Anti addition of bromine to trans-2-butene gives the meso dibromide
- Chlorohydrin formation from cyclopentene: anti addition of Cl and OH
- Hydroxide opens (2R,3R)-2,3-dimethyloxirane to meso-butane-2,3-diol
- NaBH4 reduces butan-2-one to racemic butan-2-ol
- SN1 methanolysis of (S)-2-chloro-2-phenylbutane with racemisation
- Azide converts cis-1-bromo-3-methylcyclohexane into the trans azide
- Cyanide displaces bromide from (R)-2-bromobutane with inversion
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O que você vai aprender
- Rank substituents by CIP priority and assign R or S to a stereocentre drawn with wedges, in a Fischer projection, or with the lowest-priority group toward you.
- Classify pairs of stereoisomers as enantiomers, diastereomers, identical or meso, and count the stereoisomers of a compound.
- Analyse Fischer projections, Newman projections and chair conformations to find stable conformers and symmetry.
- Relate optical rotation to enantiomeric excess, calculate specific rotation and plan a resolution.
- Predict the stereochemical outcome of SN2, SN1, bromonium-ion additions, epoxide openings and additions to planar carbonyl groups.
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Stereocentres and CIP priorities
A tetrahedral carbon with four different groups is a stereocentre (chirality centre); swapping any two of its groups gives a different stereoisomer. To rank the groups, compare the atomic numbers of the atoms directly attached: Br > Cl > O > N > C > H. If two attached atoms tie, list the three atoms each one carries and compare the highest of each set first, moving outward one sphere at a time until the first difference. A double or triple bond counts as two or three single bonds to duplicated atoms, so –CH=CH₂ carries (C, C, H) and –C≡CH carries (C, C, C). A single heavier atom beats any number of lighter ones: –CH₂OH (O, H, H) outranks –C(CH₃)₃ (C, C, C). In alanine the order is NH₂ > COOH > CH₃ > H.
Assigning R and S
Point the lowest-priority group away from you and trace 1 → 2 → 3. Clockwise is R, counterclockwise is S. If the lowest-priority group is on a wedge (toward you), trace as drawn and reverse the answer. Exchanging any two groups converts R into S; two exchanges restore the original configuration. The descriptor depends only on priorities, so it says nothing about the sign of optical rotation. (R)-2-Bromobutane is shown: Br > CH₂CH₃ > CH₃ > H.
Enantiomers, diastereomers and meso compounds
Enantiomers are non-superimposable mirror images: every stereocentre is inverted, (2R,3R) versus (2S,3S). Diastereomers are stereoisomers that are not mirror images: some but not all centres differ, (2R,3R) versus (2R,3S). A compound with n stereocentres has at most 2ⁿ stereoisomers. When the two halves of the molecule are built the same way, the (R,S) combination has an internal mirror plane and is a single achiral meso compound, so 2,3-dibromobutane has only three stereoisomers: the (R,R)/(S,S) pair and the meso form. Ring compounds behave the same way: cis-1,2-dimethylcyclohexane is meso, while trans-1,2-dimethylcyclohexane is chiral.
Fischer projections, Newman projections and chairs
In a Fischer projection, horizontal bonds point toward you and vertical bonds point away. With H on a horizontal bond, trace 1 → 2 → 3 and reverse the result. Rotating a Fischer projection by 180° in the plane gives the same molecule; rotating by 90° gives the enantiomer. In a Newman projection of butane, energy rises from anti (0) to gauche (about 3.8 kJ/mol) to CH₃/H eclipsed (about 16 kJ/mol) to CH₃/CH₃ eclipsed (about 19 kJ/mol). In a cyclohexane chair, a substituent prefers the equatorial position to avoid 1,3-diaxial interactions; for methyl the preference is about 7.3 kJ/mol. Groups can both be equatorial in trans-1,2, cis-1,3 and trans-1,4 disubstituted cyclohexanes.
Optical activity and enantiomeric excess
Enantiomers have identical melting points, boiling points, solubilities and spectra in achiral surroundings; they differ in the sign of optical rotation and in how they interact with other chiral molecules. Specific rotation is [α] = α / (l × c), with the path length l in dm and the concentration c in g/mL. A racemic mixture (50:50) shows no rotation. Enantiomeric excess is ee = |%major − %minor| = observed [α] / [α] of the pure enantiomer × 100%, so a sample with 80% ee is 90:10. Because diastereomers have different physical properties, a racemic acid is resolved by forming salts with a single enantiomer of a chiral amine, crystallising the diastereomeric salts apart and then acidifying.
Stereochemistry of reactions
SN2 attack occurs from the side opposite the leaving group and inverts the stereocentre; whether the R/S label changes depends on the new priorities. SN1 goes through a planar carbocation, so a single enantiomer gives a racemic (or nearly racemic) product. Bromine adds through a bridged bromonium ion that is opened from the opposite face, so the two new groups end up anti: trans-2-butene gives meso-2,3-dibromobutane and cis-2-butene gives the racemic (R,R)/(S,S) pair. Base opens an epoxide by SN2 at one carbon, again with inversion. An achiral reagent adding to a planar carbonyl group attacks both faces equally, so a new stereocentre forms as a racemate.
What to carry forward
Rank by atomic number at the first point of difference, put the lowest priority away from you, and remember that two stereocentres built the same way can cancel into a meso compound. In reactions, follow the geometry first (backside attack, anti opening, planar intermediates), then reassign the labels with the new priorities.
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Desenhe o mecanismo 52
Stereochemistry of reactions
- Anti addition of bromine to cis-2-butene gives the racemic dibromideDraw bromonium-ion formation from (Z)-but-2-ene and its backside opening by bromide, and explain why the product is racemic (2R,3R)/(2S,3S)-2,3-dibromobutane.
- Anti addition of bromine to trans-2-butene gives the meso dibromideDraw bromonium-ion formation from (E)-but-2-ene and its backside opening by bromide, and show that anti addition gives meso-2,3-dibromobutane.
- Chlorohydrin formation from cyclopentene: anti addition of Cl and OHDraw the chloronium ion from cyclopentene and chlorine, its backside opening by water, and the deprotonation that gives trans-2-chlorocyclopentan-1-ol.
- Hydroxide opens (2R,3R)-2,3-dimethyloxirane to meso-butane-2,3-diolDraw the backside SN2 opening of (2R,3R)-2,3-dimethyloxirane by hydroxide and protonation of the alkoxide by water, and explain why a single enantiomer of the epoxide gives the achiral meso diol.
- NaBH4 reduces butan-2-one to racemic butan-2-olDraw hydride transfer from borohydride to butan-2-one and protonation of the alkoxide by methanol, and explain why the new stereocentre forms as a racemate.
- SN1 methanolysis of (S)-2-chloro-2-phenylbutane with racemisationDraw the SN1 methanolysis of (S)-2-chloro-2-phenylbutane through a planar benzylic cation and explain why the ether forms largely racemic.
- Azide converts cis-1-bromo-3-methylcyclohexane into the trans azideDraw the backside SN2 attack of azide on cis-1-bromo-3-methylcyclohexane and explain why the product is trans-1-azido-3-methylcyclohexane.
- Cyanide displaces bromide from (R)-2-bromobutane with inversionDraw the backside SN2 attack of cyanide on (R)-2-bromobutane and assign the configuration of the (S)-2-methylbutanenitrile formed.
- Bromine adds anti to (Z)-pent-2-ene to give (2S,3S)-2,3-dibromopentaneDraw bromonium-ion formation from (Z)-pent-2-ene and its anti opening by bromide, and explain why racemic (2R,3R)/(2S,3S)-2,3-dibromopentane forms.
- (2S,3S)-2,3-Dibromobutane eliminates to (Z)-2-bromobut-2-eneDraw the anti-periplanar E2 of (2S,3S)-2,3-dibromobutane with one equivalent of hydroxide and explain why only (Z)-2-bromobut-2-ene forms.
- Hydrogenation of 1,2-dimethylcyclopentene gives cis-1,2-dimethylcyclopentaneDraw the hydrogenation of 1,2-dimethylcyclopentene on palladium and explain why both hydrogens add to the same face to give meso cis-1,2-dimethylcyclopentane.
- HBr adds to (E)-hex-3-ene to give racemic 3-bromohexaneDraw protonation of (E)-hex-3-ene by HBr and capture of the carbocation by bromide, and explain why 3-bromohexane forms as a racemate.
- Hydroboration–oxidation of 1-ethylcyclohexene gives trans-2-ethylcyclohexan-1-olDraw the syn addition of borane to 1-ethylcyclohexene and the oxidation with basic hydrogen peroxide, and explain why the alcohol is trans to the ethyl group.
- Cold permanganate turns (E)-stilbene into (1R,2R)-hydrobenzoinDraw the cycloaddition of permanganate to (E)-stilbene and the hydrolysis of the cyclic manganate ester, and explain why syn addition gives racemic (1R,2R)/(1S,2S)-1,2-diphenylethane-1,2-diol.
- mCPBA converts (E)-pent-2-ene into (2R,3R)-2-ethyl-3-methyloxiraneDraw the one-step transfer of oxygen from mCPBA to (E)-pent-2-ene and explain why the epoxide keeps the trans relationship of the alkene.
- Hydroxide opens meso-2,3-dimethyloxirane to (2S,3S)-butane-2,3-diolDraw the backside opening of cis-2,3-dimethyloxirane by hydroxide and the protonation of the alkoxide, and explain why the meso epoxide gives a racemic diol.
- OsO4 dihydroxylation of cyclopentene gives cis-cyclopentane-1,2-diolDraw the cycloaddition of OsO4 to cyclopentene and the hydrolysis of the osmate ester, and explain why the diol is cis and meso.
- Simmons–Smith cyclopropanation of (E)-but-2-ene gives trans-1,2-dimethylcyclopropaneDraw the concerted transfer of CH2 from the Simmons–Smith reagent to (E)-but-2-ene and explain why the methyl groups stay trans.
- Ethanolysis of (R)-3-chloro-3-methylhexane gives racemic 3-ethoxy-3-methylhexaneDraw the SN1 ethanolysis of (R)-3-chloro-3-methylhexane through the planar tertiary carbocation and explain why the ether is racemic.
- Hydrosulfide displaces tosylate to give (S)-butane-2-thiolDraw the SN2 displacement of tosylate from (R)-butan-2-yl tosylate by hydrosulfide and assign the configuration of the thiol.
- Hydroxide converts (S)-2-bromooctane into (R)-octan-2-olDraw the backside attack of hydroxide on (S)-2-bromooctane and show that (R)-octan-2-ol forms with inversion of configuration.
- Iodide converts cis-1-bromo-4-methylcyclohexane into trans-1-iodo-4-methylcyclohexaneDraw the SN2 attack of iodide on cis-1-bromo-4-methylcyclohexane and explain why the product is the trans iodide.
Estereoquímica de reações
- Adição de Br2 ao 1-metilciclo-hexeno: dibrometo transDesenhe o mecanismo via íon bromônio da adição de Br2 ao 1-metilciclo-hexeno e explique por que os dois bromos ficam trans.
- Adição de Br2 ao (E)-2,5-dimetil-hex-3-eno: dibrometo mesoDesenhe a adição anti de Br2 ao (E)-2,5-dimetil-hex-3-eno e mostre por que o dibrometo é meso.
- Bromidrina trans a partir de 1-etilciclo-hexeno com NBS e águaDesenhe a formação do íon bromônio a partir do 1-etilciclo-hexeno e NBS, sua abertura pela água no carbono terciário, e explique por que OH e Br ficam trans.
- Cl2 em metanol transforma ciclo-hexeno em um cloroéter transDesenhe a formação do íon clorônio a partir do ciclo-hexeno e sua abertura anti pelo metanol, e explique por que se forma trans-1-cloro-2-metoxiciclo-hexano em vez do dicloreto.
- Cloridrina a partir do (Z)-but-2-eno: adição anti de Cl2 e águaDesenhe o mecanismo de formação da cloridrina a partir do (Z)-but-2-eno com Cl2 em água e atribua a estereoquímica do 3-clorobutan-2-ol.
- D2 se adiciona syn ao (Z)-but-2-eno: meso-2,3-dideuterobutanoDesenhe a adição de deutério ao (Z)-but-2-eno sobre paládio e explique por que a adição syn ao alceno Z gera o dideuterobutano meso.
- E2 do (2S,3S)-2-bromo-3-ciclo-hexilbutano com etóxidoDesenhe a E2 antiperiplanar do (2S,3S)-2-bromo-3-ciclo-hexilbutano e explique por que se forma o (E)-but-2-en-2-ilciclo-hexano.
- E2 do (3R,4R)-3-bromo-4-fenil-hexano: (E)-3-fenil-hex-3-enoDesenhe a E2 antiperiplanar do (3R,4R)-3-bromo-4-fenil-hexano e deduza por que o (E)-3-fenil-hex-3-eno é o único alceno.
- E2 do cis-1-cloro-2-etilciclo-hexano: 1-etilciclo-hexenoDesenhe a eliminação E2 do cis-1-cloro-2-etilciclo-hexano com etóxido e explique por que o alceno de Zaitsev, 1-etilciclo-hexeno, é o principal.
- E2 do cloreto de mentila com etóxido: só 2-mentenoDesenhe a eliminação E2 do cloreto de mentila com etóxido e explique por que o 2-menteno é o único alceno.
- E2 do cloreto de neomentila com etóxido: 3-mentenoDesenhe a eliminação E2 do cloreto de neomentila com etóxido e explique por que o alceno de Zaitsev, 3-menteno, é o principal.
- E2 do trans-1-bromo-2-isopropilciclo-hexano com etóxidoDesenhe a eliminação E2 do trans-1-bromo-2-isopropilciclo-hexano e explique por que se forma 3-isopropilciclo-hexeno em vez do alceno de Zaitsev.
- E2 do trans-1-cloro-2-etilciclo-hexano: 3-etilciclo-hexenoDesenhe a eliminação E2 do trans-1-cloro-2-etilciclo-hexano com etóxido e explique por que o produto é o 3-etilciclo-hexeno.
- Metanol ácido abre o óxido de 1-metilciclo-hexenoDesenhe a abertura catalisada por ácido do óxido de 1-metilciclo-hexeno pelo metanol e explique por que o grupo metóxi vai para o carbono terciário, trans ao OH.
- NaOMe abre o óxido de ciclo-hexeno a trans-2-metoxiciclo-hexanolDesenhe o ataque pelo lado oposto do metóxido ao óxido de ciclo-hexeno e a protonação do alcóxido, e explique por que os grupos metóxi e hidroxila ficam trans.
- HBr se adiciona ao 1,2-dimetilciclo-hexeno via cátion planoDesenhe a protonação do 1,2-dimetilciclo-hexeno pelo HBr e a captura do cátion terciário pelo brometo, e explique por que se formam tanto o cis quanto o trans-1-bromo-1,2-dimetilciclo-hexano.
- Hidroboração do 1-isopropilciclo-hexeno: o álcool transDesenhe a adição syn do borano ao 1-isopropilciclo-hexeno e a oxidação com peróxido em meio básico, e explique por que o OH fica trans ao grupo isopropila.
- mCPBA epoxida o (Z)-hex-3-eno a cis-2,3-dietiloxiranoDesenhe a transferência concertada de oxigênio do mCPBA para o (Z)-hex-3-eno e explique por que o alceno cis gera o epóxido cis meso.
- OsO4 transforma o 1,2-dimetilciclo-hexeno no diol cisDesenhe o éster ósmico cíclico formado a partir do 1,2-dimetilciclo-hexeno e sua hidrólise, e explique por que os dois grupos OH ficam cis em um diol meso.
- Simmons–Smith no (E)-1-fenilpropeno: ciclopropano transDesenhe a transferência concertada de CH2 do carbenoide de Simmons–Smith para o (E)-1-fenilpropeno e explique por que os grupos metila e fenila continuam trans.
- Hidrólise SN1 do (1S,3R)-1-cloro-1,3-dimetilciclo-hexanoDesenhe a hidrólise SN1 do (1S,3R)-1-cloro-1,3-dimetilciclo-hexano e explique por que os dois álcoois são diastereoisômeros.
- Hidrólise SN1 do (R)-3-bromo-3-metil-heptanoDesenhe a hidrólise SN1 do (R)-3-bromo-3-metil-heptano e explique por que o 3-metil-heptan-3-ol se forma como racemato.
- Hidrólise SN1 do cloreto de (S)-1-(4-metoxifenil)etilaDesenhe a hidrólise SN1 do cloreto de (S)-1-(4-metoxifenil)etila, incluindo a forma de ressonância do grupo metóxi, e explique a perda de atividade óptica.
- Metanólise SN1 do 1-bromo-1,4-dimetilciclo-hexanoDesenhe a metanólise SN1 do 1-bromo-1,4-dimetilciclo-hexano e explique por que se formam tanto o éter cis quanto o trans.
- SN2 do tosilato de cis-4-terc-butilciclo-hexila com acetatoDesenhe o acetato deslocando o tosilato axial do tosilato de cis-4-terc-butilciclo-hexila e explique por que o éster é trans.
- SN2 do (S)-2-bromopentano com azida: (R)-2-azidopentanoDesenhe o ataque pelo lado oposto da azida ao (S)-2-bromopentano e mostre por que o produto é o (R)-2-azidopentano.
Estereoquímica das reações
- SN2 do mesilato de trans-2-metilciclo-hexila com azidaDesenhe a azida deslocando o mesilato do mesilato de trans-2-metilciclo-hexila e explique por que a azida fica cis em relação à metila.
- SN2 do cis-1-bromo-2-metilciclopentano com cianetoDesenhe o cianeto deslocando o brometo do cis-1-bromo-2-metilciclopentano e explique por que a nitrila é trans.
- SN2 de Finkelstein do (S)-2-bromo-hexano: (R)-2-iodo-hexanoDesenhe a reação SN2 de Finkelstein do (S)-2-bromo-hexano com iodeto e atribua a configuração do (R)-2-iodo-hexano.
- SN2 do (R)-2-iodobutano com metanotiolatoDesenhe o ataque SN2 do metanotiolato ao (R)-2-iodobutano e atribua a configuração do sulfeto formado.
Preveja o produto 5
Projections and conformations
- Rotating a Fischer projection by 90°Predict how an in-plane rotation of a Fischer projection changes the configuration.
Stereochemistry of reactions
- Inversion without a change of labelPredict the R/S label of an SN2 product when the nucleophile does not take the leaving group's priority rank.
- OsO₄ dihydroxylation of cis-2-butenePredict the stereoisomer formed by syn dihydroxylation of a cis alkene.
Assigning R and S
- Exchanging groups twicePredict the configuration after two exchanges of substituents on a stereocentre.
Wave 1 practice
- Br2 adds to (E)-but-2-enePredict the stereoisomer formed by anti addition of bromine to an E alkene.
Classificar 15
Assigning R and S
- Configuration of natural alanineAssign R or S to the stereocentre of an amino acid drawn with wedge bonds.
- Which compound has a stereocentre?Identify a stereocentre by checking that a carbon carries four different groups, including ring paths.
- Find (2R,3S)-2-bromo-3-chlorobutaneMatch a two-centre name to its structure by assigning each stereocentre independently.
- Configuration of a ring stereocentreAssign R or S to a ring stereocentre by exploring both ring branches until the first point of difference.
Isomer relationships and meso compounds
- cis- and trans-1,2-dimethylcyclohexaneDecide which ring diastereomer is meso and which is chiral by looking for an internal mirror plane.
- Which compound is meso?Recognise a meso compound as one with stereocentres and an internal mirror plane, distinguishing it from chiral look-alikes.
- (2R,3S) versus (2S,3R)-2,3-dibromobutaneRecognise that inverting every centre of a meso compound returns the same compound, not an enantiomer.
- (2R,3R) versus (2R,3S)Classify two stereoisomers that differ at only one of two stereocentres and state a consequence for their properties.
- (2R,3R) versus (2S,3S)Classify two stereoisomers whose every stereocentre is inverted as enantiomers.
- The mirror image of L-threonineChoose the enantiomer of a two-centre amino acid by inverting every stereocentre.
Projections and conformations
- R or S from a Fischer projectionAssign R or S from a Fischer projection in which the hydrogen lies on a horizontal bond.
Atribuição de R e S
- R ou S: o estereocentro da (−)-carvona da hortelãAtribua R ou S a um estereocentro do anel cujos dois ramos do anel só diferem no segundo átomo.
Wave 1 practice
- Assign R or S to 2-bromobutaneAssign a CIP descriptor by ranking substituents and reading the direction with H away.
- Relationship between (2R,3R)- and (2R,3S)-2,3-dibromopentaneClassify a stereoisomer pair from its descriptors.
Relações entre isômeros e compostos meso
- (1R,2R)- versus (1S,2S)-1,2-dimetilciclo-hexanoClassifique dois ciclo-hexanos trans-1,2-dissubstituídos que têm todos os descritores invertidos.
Comparar 6
Projections and conformations
- Rank the conformations of butaneOrder the staggered and eclipsed Newman conformations of butane by energy and name the interaction responsible for each.
- Which 1,3-dimethylcyclohexane can be diequatorial?Use chair geometry to decide which 1,3-disubstituted cyclohexane diastereomer can place both groups equatorial.
Assigning R and S
- Rank six carbon-based groups by CIP priorityRank alkyl, alkenyl, alkynyl and hydroxymethyl groups by exploring CIP priorities sphere by sphere with duplicated atoms.
- Rank five common substituents by CIP priorityRank heteroatom and carbon substituents by CIP priority using atomic number and duplicated atoms for C=O bonds.
Optical activity and resolution
- What differs between enantiomers?Compare the physical properties of two enantiomers and identify the one that differs.
Relações entre isômeros e compostos meso
- Ordene quatro cloroalcanos pelo número de estereoisômerosClassifique cloroalcanos pelo número de estereoisômeros, reconhecendo quando a simetria gera uma forma meso.
Calcular 10
Isomer relationships and meso compounds
- Stereoisomers of an open-chain aldohexoseApply the 2ⁿ rule to a chain whose ends differ, after locating every stereocentre.
- Count the stereoisomers of 2,3-dichlorobutaneCount the stereoisomers of a symmetric compound with two stereocentres, allowing for a meso form.
Optical activity and resolution
- Enantiomeric excess from optical rotationCalculate enantiomeric excess from the observed specific rotation of a partly resolved sample.
- Composition of an 80% ee sampleConvert an enantiomeric excess into the percentage of the major enantiomer.
- Calculate a specific rotationCalculate a specific rotation from an observed rotation, concentration and path length in the correct units.
Projections and conformations
- Equatorial methylcyclohexane at equilibriumConvert an axial–equatorial free-energy difference into an equilibrium percentage of the equatorial chair.
Relações entre isômeros e compostos meso
- Estereoisômeros do ácido 2,3,4-tri-hidroxiglutáricoConte os estereoisômeros de uma cadeia simétrica com um carbono central pseudoassimétrico.
Wave 1 practice
- Stereoisomers of 2,3-dichlorobutaneCount stereoisomers when symmetry creates a meso compound.
- ee of a butan-2-ol sample from its rotationCalculate enantiomeric excess from observed and pure specific rotations.
Atividade óptica e resolução
- ee após misturar 3,0 g de (R) com 1,0 g de (S)Calcule o excesso enantiomérico a partir das massas de dois enantiômeros misturados.
Encontre o erro 2
Assigning R and S
- Find the error in an R/S assignmentDiagnose an R/S assignment made with the lowest-priority group pointing toward the viewer.
Atividade óptica e resolução
- O cis-1,2-diclorociclo-hexano é opticamente ativo?Encontre o erro na afirmação de que um ciclo-hexano meso é opticamente ativo porque uma das conformações cadeira é quiral.
Interprete as evidências 4
Projections and conformations
- Reading tartaric acid in a Fischer projectionInterpret a two-centre Fischer projection by looking for a horizontal mirror plane.
- Newman projection of meso-2,3-dibromobutaneInterpret a Newman projection of a meso compound to locate the remaining groups once two groups are placed anti.
Projeções e conformações
- R ou S a partir de uma projeção de Newman do 2-bromobutanoAtribua R ou S ao carbono da frente de uma projeção de Newman em que o grupo que aponta para trás não é o de menor prioridade.
Wave 1 practice
- Anti-bromine conformer of (2R,3R)-2,3-dibromobutaneRelate a staggered Newman conformer to the configuration of a chiral versus meso diastereomer.
Trabalhe de trás para frente 2
Stereochemistry of reactions
- Which bromide gives (R)-2-azidobutane?Work backwards from an SN2 product to the enantiomer of the alkyl halide required, allowing for inversion.
Estereoquímica das reações
- Qual hexeno dá hexano-3,4-diol racêmico com OsO4?Parta de um produto racêmico de di-hidroxilação syn e deduza a geometria do alceno necessária.
Planeje uma síntese 2
Optical activity and resolution
- Resolve a racemic carboxylic acidPlan the resolution of a racemic acid by converting the enantiomers into separable diastereomeric salts.
Estereoquímica das reações
- Converta o (R)-butan-2-ol em (S)-2-bromobutanoEscolha um reagente de etapa única que transforme um álcool secundário quiral no brometo de alquila com inversão limpa.
Explique por quê 2
Optical activity and resolution
- Why a racemate shows no rotationExplain why a racemic mixture of chiral molecules is optically inactive.
Estereoquímica das reações
- Por que a SN1 do (R)-3-bromo-3-metil-hexano racemizaExplique a perda de configuração em uma hidrólise SN1 a partir da geometria do carbocátion.
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