Phthalimides, conjugate

The two-step procedure includes formation of a N-substituted phthalimide 3, and its subsequent cleavage to the primary amine 5. Phthalimide (which can be obtained from reaction of phthalic acid with ammonia) shows NH-acidity, since the negative charge of the phthalimide anion (the conjugated base) is stabilized... 

As mentioned in chapter 4.2.3, aliphatic imines are photochemically rather unreactive. When the C—N double bond is conjugated to an electron withdrawing group (e.g. carbonyl group), as in O-alkyl derivatives of succinimide and phthalimide, the reactivity increases and azetidines are obtained in cycloadditions to olefins486). A somehow similar example is the photoaddition of a 6-azauracil derivative to 2,3-dimethyl-2-butene... 

Diastereoselective tandem conjugate addition of both oxygen- and nitrogen-centred nucleophiles (potassium phthalimide, TsNHK, MeONa, and MesSiOK) to the novel (IN)-lO-camphorsulfonic acid-derived nitroalkenes (139 R = Me, Pr, and... 

The Gabriel synthesis of amines uses potassium phthalimide (prepared from the reaction of phthalimide with potassium hydroxide). The structure and preparation of potassium phthalimide is shown in Figure 13-13. The extensive conjugation (resonance) makes the ion very stable. An example of the Gabriel synthesis is in Figure 13-14. (The N2H4 reactant is hydrazine.) The Gabriel synthesis employs an 8, 2 mechanism, so it works best on primary alkyl halides and less well on secondary alkyl halides. It doesn t work on tertiary alkyl halides or aryl halides. 

Where there are two carbonyl groups to stabilize the amide anion, as in the l,2-benzenedicarboximide (phthalimide) anion (Section 18-IOC), the acidity increases markedly and imides can be converted to their conjugate bases with concentrated aqueous hydroxide ion. We have seen how imide salts can be used for the synthesis of primary amines (Gabriel synthesis, Section 23-9D and Table 23-6). 

A PET reaction between excess phthalimide (in equilibrium with its conjugate base) and an alkene led to a clean phthalimidation of nonactivated double bonds. Here, the singlet excited state of phthalimide acts as the oxidant and a radical ion pair is formed. The olefin cation radical is trapped by the phthalimide anion, and back electron transfer, followed by protonation, affords the photoaddition products [40], Protected phenethylamines are readily accessible in this way. This reaction has been carried out by using NaOH as the base it has been shown that the amounts (usually equimolar with the alkene) must be carefully chosen in order to avoid the undesired competition with [2 + 2] photocycloaddition. 

O Because of resonance, the electron pair on the nitrogen of phthalimide is not very basic or nucleophilic. The hydrogen on the nitrogen is much more acidic than a hydrogen of a normal amine because the conjugate base is stabilized by resonance. It is acidic enough to be removed completely by a base such as hydroxide ion. 

In a similar manner the conjugate base of phthalimide is used as the synthetic equivalent of amide ion for the preparation of primary amines in the Gabriel synthesis (see Section 10.6 and Figure 10.5). 

Machida et al., 1980a). When 1,1-diphenylethylene is used as the alkene and methanol is used as solvent, adducts such as [142] are produced which indicate that the reaction occurs by an electron-transfer process (Scheme 33) (Maruyama and Kubo, 1978b). Phthalimides also react with conjugated dienes to give ring expansion products (Mazzocchi et al., 1978b, 1977) only one of the... 

Very recently, the conjugate addition of phthalimide salts to chiral a,/ -unsaturated imides has been reported. After further transformations, optically active /J-amino acid derivatives were obtainedl37. 

Addition to alkynoic esters. Conjugate addition of oximes to alkynoic esters to provide ( j-alkenyl oxime ethers is catalyzed by PhjP. Interestingly, a-addition by phthalimide is observed. Such adducts are useful precursors of dehydro-a-amino acids. ... 

Imines conjugated with electron-withdrawing carbonyl or aryl functions at nitrogen or carbon appear to more readily participate in cycloadditions. This was shown for 6-azauracil derivatives io2,103 ancj 3-ethoxyisoindole 9104-105, both reactions are thought to proceed via the triplet state of the electronically excited imines. The isoindole photochemistry, to some extent, resembles the reactions of phthalimides described in Section 1.6.1.4.3.8. For example, the azetidine 10 can be converted to the azepinedione derivative 11 using acid. 

Phenylselenofluoration of acetylenes 359 (R = Pr or Bu) to give 360 is accomplished by the joint action of A-(phenylseleno)phthalimide and EtsN-SHF. Free-radical selenosulphonation of conjugated enynes by PhSeTos under photochemical conditions or in the presence of azoisobutyronitrile yields mixtures of stereoisomers, e.g. equation The action of / -methoxyphenyltellurium trichloride on terminal alkynes RC=CH (R = cyclohexyl, HOCH2 or Ar) results in cw-adducts 361 (Ar = -MeOC6H4) 48 Sodium benzenetellurolate, PhTeNa, formed in situ from diphenyl ditelluride and sodium borohy-... 

Phthalimide is acidic, since its conjugate base is resonance stabilised. Bromine is an electrophile, since it is electronegative and bromide is a good leaving group. Sodium hydroxide is a good base. 

Kang and co-workers have reported reactions of open-chain vinyl-substituted cyclic carbonates with many stabilized and nonstabilized carbon nucleophiles,heteroatom nucleophiles, hydride equivalent,and vinyl and aryltin reagents. Retention of configuration has been observed for malonate, for thiophenolate, and for the conjugate base of phthalimide. In the absence of nucleophile a proton elimination ensues (Scheme 44). The reaction with iodobenzene produces a reductive ring opening by a variant of the Heck reaction. ... 

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