BackA common situation occurs when both carbons of the mercurinium ion are secondary. In a situation like the one shown, to which carbon would you expect water to add? That is, would you expect to produce A or B? Explain your answer.
Show how you would accomplish the following synthetic conversions.
a. but-1-ene → 2-methoxybutane
b. 1-iodo-2-methylcyclopentane → 1-methylcyclopentanol
a. Propose a mechanism for the following reaction.
b. Give the structure of the product that results when this intermediate is reduced by sodium borohydride.
Show how you would synthesize each compound using methylenecyclohexane as your starting material.
(a)
In 1973, Caine and Tuller reported a synthesis of racemic oplapanone, a sesquiterpene isolated from Oplopanax japonicus (a deciduous shrub) involving a reaction we learned in this chapter. Predict the product of the reaction shown. (Caine, D.; Tuller, F. N. J. Org. Chem. 1973, 38, 3663.)
Would you expect the following to produce an equal or unequal mixture of stereoisomers?
(c)
Predict the major products of the following reactions, and give the structures of any intermediates. Include stereochemistry where appropriate.
(p)
For the alkynes shows here, show the product(s) expected to form when treated under the following conditions: (vi) H2SO4, HgSO4, H2O. If you expect two products, show both.
(c)
Oxymercuration–reduction, like acid-catalyzed hydration, can be modified to synthesize ethers. Suggest an alkene and the appropriate reaction conditions to synthesize the following ethers.
(b)
Predict the product(s) that would result when the alkenes shown here are allowed to react under the following conditions: (v) 1. Hg(OAc)2 , H2O 2. NaBH4
(k)
Would you expect the following to produce an equal or unequal mixture of stereoisomers?
(a)
Show how you would accomplish the following synthetic conversions.
c. 3-methylpent-1-ene → 3-methylpentan-2-ol
Explain why acid-catalyzed hydration would be a poor choice for the reaction in (c).
Provide an arrow-pushing mechanism, accounting also for the stereochemical outcome, of the first step (oxymercuration) of the three reactions in Figure 8.63.
The formation of five-membered ring ethers is an important goal in synthetic organic chemistry because tetrahydrofurans are contained within a number of antitumor natural products. Toward that end, a one-pot synthesis of a bis-THF containing compound was developed (Eur. J. Org. Chem. 2010, 6263–6268). Suggest a mechanism for this transformation.
Predict the major products of the following reactions.
a. 1-methylcyclohexene+ aqueous Hg(OAc)2
b. the product from part (a), treated with NaBH4