Diethylamine, reaction with epoxides

Optically pure tri(hydroxyalkyl)amines 29 (R = Me, t-Bu, cyclohexyl or Ph) have been obtained from enantiomerically pure epoxides and methanolic ammonia63. Tetraphenylsti-bonium trifluoromethanesulphonate, SbPhzj1 C.f 3S03, catalyses the reaction of epoxides with amines, e.g. diethylamine or aniline, to yield 2-hydroxyalkylamines in quantitative yields (equation 25)64. 

Isomerization of the epoxide (IV) with pyrrolidine was carried out as described by Sih (8) and consistently gave yields of 35-60% rather than the 73% reported. Changes in experimental conditions including longer reaction times at lower temperatures, use of freshly distilled pyrrolidine, use of NaOH dried pyrrolidine, and use of distilled epoxide (IV) had little effect on the yield. The only variation that improved the yield was to allow the reaction to proceed at ambient temperature for a longer period of time than the recommended 3 hours. Allowing the reaction to proceed for 40 hours provided a maximum 67.5% yield. Other bases such as sodium carbonate, tri ethyl amine, diethylamine l,5-diazabicyclo[4.3.0]non-5-ene(DBN), and sodium methoxide all gave lower yields of distilled product than pyrrolidine. It is important to use the hydroxyaldehyde (V) as soon as possible since it is a very unstable material. 

For example, diethylamine sensitizes the photodegradation of DDT to yield DDE, TDE, dichlorobenzophenone, and two other unidentified compounds (6).. These reactions are thought to involve a charge transfer from the amine to DDT. Similarly, rotenone is highly effective in enhancing the photochemical alteration of dieldrin to photodieldrin ( 7). Rotenone also catalyzes the photochemical alteration of aldrin, isodrin, endrin, heptachlor, and heptachlor epoxide but it is less effective or ineffective with DDT, DDE, lindane, and endosulfan (7, 8). 

A tungsten-promoted intramolecular [3-1-2] cycloaddition reaction of an alkyne and epoxide leads to the formation of air-isomers of reduced furo[3,4-c]pyrans, as shown in Equation (68) <2001JA7427>. The alkynyltungsten complexes were prepared in good yields from the corresponding alkynes upon treatment with CpWlCOlsCl and diethylamine <1997JA4404>. 

Subsequently, other workers including O Neill and Cole (4 and Dannenberg (5 ) showed that Reactions 2 and 3 proceed to the exclusion of Reaction 4. The reactivity of a particular epoxide-amine system depends on the influence of the steric and electronic factors associated with each of the reactants. It has been known for some time that hydroxyls play an important role in the epoxide-amine reaction. For example, Shechter et al. ( ) studied the reaction of diethylamine with phenylglycidyl ether in concentrated solutions. They showed that acetone and benzene decreased the rate of reaction in a manner consistent with the dilution of the reactants, but that solvents such as 2-propanol, water, and nitromethane accelerated the reaction (Figure 3). They also found that addition of 1 mol of phenol to this reaction accelerated it to an even greater extent that addition of 2-propanol or water. 

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