Interpretation:
The observation that photolysis of cis-cyclobutene yields cis-cyclododecaen-7-yne but photolysis of trans-cyclobutene yields trans-cyclododecaen-7-yne is to be explained by identifying the type and stereochemistry of the pericyclic reaction involved.
Concept introduction:
An electrocyclic reaction involves the cyclization of a conjugated acyclic system. These reactions are reversible and are highly stereospecific.
In elecrocyclic reactions involving even number of electron pairs, a thermal reaction occurs in conrotatory manner and a photochemical reaction occurs in disrotatory manner.
In elecrocyclic reactions involving odd number of electron pairs, a thermal reaction occurs in disrotatory manner and a photochemical reaction occurs in conrotatory manner.
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Organic Chemistry
- Draw the product of each electrocyclic reaction.a. the thermal electrocyclic ring closure of (2E,4Z,6Z)-nona-2,4,6-trieneb. the photochemical electrocyclic ring closure of (2E,4Z,6Z)-nona-2,4,6-trienec. the thermal electrocyclic ring opening of cis-5-ethyl-6-methylcyclohexa-1,3-diened. the photochemical electrocyclic ring opening of trans-5-ethyl-6-methylcyclohexa-1,3- dienearrow_forwardis steric hinderance not an issue here? why when reacting with KOC(CH3)3 does it yield 2-isopropyl-1-pentene and it yields 2,3-dimethyl-2hexene here?arrow_forwardDraw mechanism arrows and then predict the major products and stereochemistry. Also include the labels of thermodynamic and kinetic 1-methylcyclohexene with BH3 followed later with –OH, H2O2, and H2O.arrow_forward
- A chemist allows some pure (2S,3R)-3-bromo-2,3-diphenylpentane to react with a solution of sodium ethoxide(NaOCH2CH3) in ethanol. The products are two alkenes: A (cis-trans mixture) and B, a single pure isomer. Under thesame conditions, the reaction of (2S,3S)-3-bromo-2,3-diphenylpentane gives two alkenes, A (cis-trans mixture) and C.Upon catalytic hydrogenation, all three of these alkenes (A, B, and C) give 2,3-diphenylpentane. Determine the structuresof A, B, and C; give equations for their formation; and explain the stereospecificity of these reactionsarrow_forwardPredict the major products of the following reactions. Include appropriate stereochemistry in the product structures. S-1,3-dimethylcyclohexene + aqueous Hg(OAc)2Hg(OAc)2 followed by treatment with NaBH4arrow_forwardClassify each pericyclic reaction as an electrocyclic reaction,cycloaddition, or sigmatropic rearrangement. Indicate whether thestereochemistry is conrotatory, disrotatory, suprafacial, or antarafacial.arrow_forward
- Bicyclo-2,5-heptadiene can be prepared in two steps from cyclopentadiene and vinyl chloride. Provide a mechanism for each step.arrow_forwardPredict the major products formed when 2- methyl-1-butene reacts with: H2, Pt/25°C. Show the reaction mechanism the given alkene reactionsarrow_forwardConsider a reaction where cis-but-2-ene is treated with a peroxy acid followed by OH- /H20. Draw the structure of one product that is formed in the reaction, including correct stereochemistry.arrow_forward
- Does the data provide evidence for the claim that the reaction of Br2 with alkenes proceeds via anti‐addition? The mleting point of the product was found to be 234.5-235.5C chemical reaction: trans-stilbene+pyrimindine tribromide --->acetic acid 1,2-di bromo-1,2-diphenylethane product was trans-1,2-dibromo-1,2-diphenylethanearrow_forwardOChem HELP... Draw the conformational structures (chair or boat conformations) for the MAJOR product formed when 1-tert-butylcyclohexene reacts with each of the following reagents. Also, indicate if the product obtained is racemic form. a) Br2, CCl4 b) Br2, H2O c) OsO4, then aqueous NaHSO3 d) ICl e) mCPBA, then H3O+, H20 f) O3, then Me2S (conformational structure not required) g) BH3:THF, then H2O2, HO- h) D2, Pt i) Hg(OAc)2 in THF-H2O, then NaBH4, HO- j) BD3 :THF, then CH3CO2Tarrow_forwardThe HCo(CO)4complex can catalyze the isomerization of pure cis-2-butene to a mixture of cis-2-butene, trans-2-butene, and 1-butene. Propose a mechanism. Carefully show the process using wedges and dashes to indicate stereochemistry of each intermediate.arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning