Concept explainers
(a)
Interpretation: The formation of both the isomeric products from the starting material by a sigmatropic rearrangement involving a
Concept introduction: In the sigmatropic rearrangement, the rearrangement of pi bond and the breaking of sigma bond take place. This results in the generation of new sigma bond in the product. In this type of rearrangement, the number of pi bonds remains constant in the reactant as well as in the product.
(b)
Interpretation: The reasons as to why
Concept introduction: In the sigmatropic rearrangement, the rearrangement of pi bond and the breaking of sigma bond take place. This results in the generation of new sigma bond in the product. In this type of rearrangement, the number of pi bonds remains constant in the reactant as well as in the product.
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ORGANIC CHEMISTRY-STUDY GDE./SOL.MAN.
- (a) Draw all stereoisomers formed by monochlorination of the cis and trans isomers of 1,2-dimethylcyclobutane drawn below. (b) How many constitutional isomers are formed in each reaction? (c) Label any pairs of enantiomers formed.arrow_forwardThe alkene shown undergoes bromination. (a) Draw the product(s) of bromination of this compound, including all expected stereoisomers (if any). Use wedge‑and‑dash bonds to designate the stereochemistry at any chirality centers, and make sure to draw an explicit hydrogen if a chirality center has one. (b) Characterize the starting alkene as having the E or Z configuration. (c) characterize the product(s).arrow_forwardThe alkene shown undergoes bromination. H (a) Draw the product(s) of bromination of this compound, including all expected stereoisomers (if any). Use wedge-and-dash bonds to designate the stereochemistry at any chirality centers, and make sure to draw an explicit hydrogen if a chirality center has one. (b) Characterize the starting alkene as having the E or Z configuration. (c) characterize the product(s). (a) H Br₂ Draw the product(s) of bromination. Br H Brarrow_forward
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- Furan and maleimide undergo a Diels–Alder reaction at 25 °C to give the endo isomer of the product. When the reactiontakes place at 90 °C, however, the major product is the exo isomer. Further study shows that the endo isomer of theproduct isomerizes to the exo isomer at 90 °C.furan: O maleimide:OON H(a) Draw and label the endo and exo isomers of the Diels–Alder adduct of furan and maleimide.(b) Which isomer of the product would you usually expect from this reaction? Explain why this isomer is usually favored.(c) Examine your answer to (b) and determine whether this answer applies to a reaction that is kinetically controlled orone that is thermodynamically controlled, or both.(d) Explain why the endo isomer predominates when the reaction takes place at 25 °C and why the exo isomer predominates at 90 °Carrow_forwardWhen buta-1,3-diene (CH2 = CH – CH = CH2) is treated with HBr, two constitutional isomers are formed, CH3CHBrCH = CH2 and BrCH2CH = CHCH3. Draw a stepwise mechanism that accounts for the formation of both products.arrow_forwardThe bicyclic alkene P can be prepared by thermal electrocyclic ringclosure from cyclodecadiene Q or by photochemical electrocyclic ringclosure from cyclodecadiene R. Draw the structures of Q and R, andindicate the stereochemistry of the process by which each reactionoccurs.arrow_forward
- Elimination occurs when (Z)-3-bromohex-3-ene is treated with NaNH2. Under the same conditions, 1-bromocyclohexeneundergoes elimination much more sluggishly. Explain whyarrow_forwardWhen (CH3)3C-C=C-H is treated with HCI, (CH3)2C(CI)C(CH3)C=CH₂ is formed as a minor product. Suggest a mechanism that would account for this transformation.arrow_forward(a) What product is formed when triene N undergoes thermal electrocyclic ring closure? (b) What product is formed when triene N undergoes photochemical ring closure? (c) Label each process as conrotatory or disrotatory.arrow_forward
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