From an Alkene

According to Le Chatelier s principle, a system at equilibrium adjusts so as to mini mize any stress applied to it When the concentration of water is increased the system responds by consuming water This means that proportionally more alkene is converted to alcohol the position of equilibrium shifts to the right Thus when we wish to pre pare an alcohol from an alkene we employ a reaction medium m which the molar con centration of water is high—dilute sulfuric acid for example... 

By application of the Simmons-Smith reaction it is possible to synthesize a cyclopropane from an alkene by formal addition of carbene to the carbon-carbon double bond, without a free carbene being present in the reaction mixture the... 

The necessary vicinal dihalides are themselves readily available by addition of Br2 or Cl2 to alkenes. Thus, the overall halogenation/dehvdrohalogenation sequence makes it possible to go from an alkene to an alkyne. for example, diphenylethylene is converted into diphenylacetylene by reaction with Br2 and subsequent base treatment. 

At the end of this section, carbolithiation-based domino processes will be discussed in which a bond and a new lithium organic moiety from an alkene and a starting lithium compound is produced. The new lithium compound can react with another C-C-double or -triple bond and finally with an electrophile, as depicted in Scheme 2.121 [283],... 

Also referred to as the oxo process or hydrocarbonylation, hydroformylation is a route to producing an aldehyde from an alkene, hydrogen, and carbon monoxide. This process has been known for approximately 70 years, and it is still economically important because useful compounds are produced in enormous quantities by this means. The reaction is summarized by the following equation ... 

Figure LI. Some of the products that can form from an alkene, carbon momoxide, hydrogen and methanol. The asterisks represent asymmetric centres in chiral molecules...

The formation of 1,2,3-trioxolanes from an alkene and ozone is the first step in the ozonolysis reaction, which is widely used in synthesis to convert alkenes to aldehydes or carboxylic acids. No instances of double bond migration during ozonolysis are known (since the first step is a cyclo-... 

This vinyl-type carbocation is less stable than its analog formed from an alkene, which has the positive charge on an sp -hybridized C atom. 

The (n,n excited state of a ketone has electrophilic character, similar to that associated with alkoxy radicals, and it is not surprising that these excited states readily attack carbon-carbon multiple bonds. The overall reaction that normally ensues is a cycloaddition, giving a four-membered oxygen heterocycle—an oxetane from an alkene addend (4.62), or an oxete from an alkyne addend (4.63). Some oxetanes are of interest in their own right, but many are useful intermediates in the synthesis of other compounds. 

It is reasonable to assume that the identical complex will be generated whether it be done stoichiometrically from an alkene, to give a chloride or carboxylate dimer followed by the addition of 2 equiv. of a phosphine per Pd, or by the addition of an allyl-X compound to give a phosphine-Pd0 complex. This assumption is supported by the fact that complexes generated in either manner have been found to exhibit identical reaction profiles.380 Furthermore, for the vast majority of allylpalladium reactions studied, it is most likely that the reactive species is a cationic bisphosphine-palladium complex (13).13 Calculations... 

The last step is an ozonolysis, which generates the aldehyde function from an alkene. 

A 1,2-diol arising from a trans-hydroxylation process is formed from an alkene by way of an intermediate epoxide which is subjected to a ring-opening reaction and hydrolysis. The epoxides may be isolated when the alkene is reacted with perbenzoic add or m-chloroperbenzoic acid (Section 4.2.56, p. 457) in a solvent such as chloroform or dichloromethane the preparation of epoxides by this method and by other important procedures are discussed and illustrated... 

The formation of epoxides is a well-investigated synthetic problem and two approaches, either from a double bond system by transfer of oxygen starting from an alkene, or carbene transfer to a carbonyl group, have attracted much interest. The use of the CpFe(CO)2+ fragment was also investigated by Hossain and coworkers with a view to its use for the synthesis of epoxides (Scheme 9.15) [30, 31]. However, the CpFe(CO)2+ fragment not only catalyzes the carbene transfer, but also acts as... 

Hydroboration provides yet another mechanism to produce an alcohol from an alkene. This is an anti-Markovnikov and a syn addition. 

In all parts of this problem you need to reason backward from an alkene to an alkyl bromide of molecular formula C7H13Br that gives only the desired alkene under E2 elimination conditions. Recall that the carbon-carbon double bond is formed by loss of a proton from one of the carbons that becomes doubly bonded and a bromine from the other. 

B-5. Which, if any, of the following alcohols cannot be prepared from an alkene ... 

Describe simple chemical tests that can distinguish an alkane from an alkene or alkyne. 

However, should you wish to make both syn and anti-diols from an alkene when only one isomer (E- or Z-) can be made, such as cyclopentene 25, you need another method. Epoxidation... 

With X and OH next to one another, an epoxide 42 looks a good bet. This would have to come from an alkene 43 and there must be a possibility of getting this from the Robinson annelation product 36 whose reduction we have just been discussing. 

Cyclic sulfates provide a useful alternative to epoxides now that it is viable to produce a chiral diol from an alkene. These cyclic compounds are prepared by reaction of the diol with thionyl chloride, followed by ruthenium-catalyzed oxidation of the sulfur (Scheme 9.26).166 This oxidation has the advantage over previous procedures because it only uses a small amount of the transition metal catalyst.167168... 

Fig. Synthesis of an ether from an alkene and an alcohol. Epoxides...

Fig. Synthesis of an alcohol from an alkene using mercuric acetate. Alkenes to Ethers...

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