BackDraw the product or products that will be obtained from the reaction of cis-2-butene and trans-2-butene with each of the following reagents. If a product can exist as stereoisomers, show which stereoisomers are formed.
3. a peroxyacid
Predict the product(s) of each of the following reactions, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.
(a)
Magnesium monoperoxyphthalate (MMPP) epoxidizes alkenes much like mCPBA. MMPP is more stable, however, and it may be safer to use for large-scale and industrial reactions. Propose a mechanism for the reaction of trans-2-methylhept-3-ene with MMPP, and predict the structure of the product(s).
What alkene would you treat with a peroxyacid in order to obtain each of the epoxides in Problem 27?
a. 2-propyloxirane
b. cyclohexene oxide
When producing a chiral molecule, epoxide formation still results in a mixture of enantiomers, despite its stereospecificity.
(b) How is it that a reaction can be stereospecific while still producing two enantiomers?
Predict the products, including stereochemistry where appropriate, for the m-chloroperoxybenzoic acid epoxidations of the following alkenes.
a. cis-hex-2-ene
b. trans-hex-2-ene
Predict the major products of the following reactions.
a. cis-hex-2-ene + mCPBA in chloroform
Write the appropriate reagent over each arrow.
Retrosynthetic analysis is the process of working backward to develop the synthesis of a new compound. In Chapter 10, we begin developing multistep syntheses in this manner. For now, try to work backward a single step by suggesting an alkene and a reagent that would give products (a)–(i). [Your answers should not include alkenes that undergo rearrangement to give the desired products.]
(f)
In Chapter 9, electron-rich alkenes were oxidized under acidic conditions with mCPBA. Conjugated alkenes can be oxidized using the same reagent, but under basic conditions. Suggest a mechanism for this reaction. [Think about what is electron-rich and what is electron-poor in the reaction. Also, identify the bonds formed and broken.]
In addition to using mCPBA, epoxides can be synthesized from alkenes in the two-step process shown. Give a mechanism for each step of the process.
Calculate the atom economy of the reaction in Figure 9.24. [Catalysts are not included in the atom economy calculation.]
Predict the product(s) when each of the following are reacted with mCPBA, making sure to indicate the relative stereochemical outcome. Indicate any racemic mixtures by drawing both enantiomers.
(a)
a. What alkene is required to synthesize each of the following compounds?
b. What other epoxide is formed in each synthesis?
c. Assign an R or S configuration to each asymmetric center.
1.