(a)
Interpretation: The stereochemistry of given reaction is to be predicted.
Concept introduction: Cycloaddition reactions are pericyclic reactions that take place in two compounds containing pi bonds to form a cyclic compound. These reactions are concerted and stereospecific in nature. According to Woodward-Hoffmann rules, the polyene containing even number of bonds in thermal conditions undergoes reaction in antrafacial fashion and polyene containing odd number of bonds undergo reaction in suprafacial fashion. The total number of bonds present in the
(b)
Interpretation: The stereochemistry of given reaction is to be predicted.
Concept introduction: Electrocyclic reactions involve ring opening or ring closure in a conjugated polyene. According to Woodward-Hoffmann rules, the polyene containing even number of bonds in photochemical conditions undergoes reaction in disrotatory fashion and polyene containing odd number of bonds undergo reaction in conrotatory fashion.
(c)
Interpretation: The stereochemistry of given reaction is to be predicted.
Concept introduction: Cycloaddition reactions are pericyclic reactions that take place in two compounds containing pi bonds to form a cyclic compound. These reactions are concerted and stereospecific in nature. According to Woodward-Hoffmann rules, the polyene containing even number of bonds in photochemical conditions undergoes reaction in suprafacial fashion and polyene containing odd number of bonds undergo reaction in antrafacial fashion. The total number of bonds present in the alkenes is considered.
(d)
Interpretation: The stereochemistry of given reaction is to be predicted.
Concept introduction: Sigmatropic rearrangements are pericyclic reactions which takes place by concerted mechanism. In these rearrangements migration of sigma bond takes place. According to Woodward-Hoffmann rules, the total number of electron pairs in sigma bond that is broken and the pi bonds that rearrange. The polyene containing even number of electron pairs and bonds in thermal conditions undergoes reaction in antrafacial fashion and polyene containing odd number of electron pairs and bonds undergo reaction in suprafacial fashion.
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Chapter 27 Solutions
Organic Chemistry
- Classify the type of cycloaddition, [m+n], identify the type of bonding possible (supra-supra, antara-antara, or supra-antara), and predict whether the reaction will proceed thermally or photochemically for each of these reactions. a. b. N S S Ph NC. CN NC CN Ph-N=N=N Ph `N S CN NC N-N N CN CN Pharrow_forwardDraw 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_forwardWhat is the major product of the following Diels-Alder cycloaddition? a. ₂CH3 X b. + CO₂CH3 CO₂CH3 CO₂CH3 d. CO₂CH3arrow_forward
- 3. Predict the products of the following Diels-Alder reactions. a. NC a. 4. Identify the diene and dienophile used to make these Diel-Alder products. CN CH3 CN CH 3 CO₂CH3 CO₂CH3arrow_forwardChemistryarrow_forward4. Identify the diene and dienophile used to make these Diel-Alder products. b. CH3 CN deo & CH3 a. CO₂CH3 CO₂CH3arrow_forward
- a. What is the major monobromination product of the following reaction? Disregard stereoisomers. b. What is the anticipated percent yield of the major product (as a percentage of all the monobrominated products)?arrow_forwarda. Show that [4+4] cycloaddition of two butadiene molecules to give cycloocta-1,5-diene is thermally forbidden but photochemically allowed b.Thermally allowed cycloaddition of the two butadiene molecules when there's a different. Show reaction and explain why it is thermally allowarrow_forwardB. Describe the stereochemistry (with structures) of the addition of Br2 and H₂O to cyclohexene. C. Arrange the following ions by increasing basicity, where 1 is the most basic and 5 is the least. HCEC CH3CH3NH2 CH3CH₂O CH3CH₂ H₂C=CHarrow_forward
- With respect to the CIP rules, assign the groups high or low priority - also what is the overall stereochemistry of the double bond?arrow_forwardPredict the products of the reactions. Show stereochemistry, using wedges and dashes, in the products and draw both enantimers.arrow_forwardD. Provide a reasonable mechanism for the Diels-Alder reaction between two molecules of cyclopenta-1,3-diene. Br 1. Mg 2.CO₂ 3. H₂O* OHarrow_forward
