Diimide dienes

Entry Sulfur Diimide Diene Conditions Product Yield Ref. 

Selenium diimides react in a manner similar to SeOa with unsaturated organic compounds. The first report of BuN=Sc=N Bu described its use as an in situ reagent for allylic amination of olefins and acetylenes. Improved procedures for this process (Eq. 10.5) and for the diamination of 1,3-dienes (Eq. 10.6) have been developed using the reagents RN=Se=NR [R = para-toluenesulfonyl (Ts), ort/io-nitrobenzenesulfonyl (Ns)]. ... 

Since the corresponding endoperoxide precursors are all too unstable for isolation, the diimide reduction constitutes an important chemical structure confirmation of these elusive intermediates that are obtained in the singlet oxygenation of the respective 1,3-dienes. However, the aza-derivative 14 and the keto-derivative 15 could not be prepared,17> because the respective endoperoxides of the pyrroles 18) and cyclopentadienones suffered complex transformations even at —50 °C, so that the trapping by the diimide reagent was ineffective. 

The reduction of dienes by diimide depends on the nature of the substitution of the diene. Several studies of relative reactivity have been carried out and they indicated that an increasing degree of alkyl substitution on the double bond results in decreasing reactivity82. In the case of allenes, the reduction of the less substituted allenic double bonds and the formation of the thermodynamically less stable cis olefin can be explained by the steric control of the approach of the diimide (equation 23)83. 

TABLE 1. Relative reactivities" in the reduction of dienes by diimide... 

The reduction of polymers can be carried out by using a diimide, generated in situ. The precursor for diimide can be p-toluenesulfonyl hydrazide (TSH), the reaction temperature is between 110-160 °C and the solvents are high boiling aromatic compounds. Possible side-reactions are cis-trans isomerization of 1,4-dienes, attachment of hydrazide fragments to the polymer, degradation and cyclization of the polymer. 

The checkers observed only partial reduction of the triene and intermediate diene under these conditions, apparently because sufficient water was present in the reaction mixture to prevent adequate partitioning of the olefins between the hydrocarbon layer and the aqueous ethanolic layer containing the diimide. The checkers avoided this difficulty by use of hydrazine containing less than 5% water (95-f- % hydrazine) available from Olin Mathieson Chemical Company or from Eastman Organic Chemicals. This difficulty could probably also be avoided by use of absolute ethanol rather than 95% ethanol. 

The behavior of dienes and polyenes - both open chain and cyclic - toward reduction depends especially on the respective positions of the double bonds. Carbon-carbon double bonds separated by at least one carbon atom behave as independent units and can be partly or completely reduced by catalytic hydrogenation or by diimide. cis, trans, /rani-l,5,9-Cyclododecatriene treated with hydrazine and air in the presence of copper sulfate (diimide in situ) gave cij-cyclododecene in 51-76% yield [269]. It appears as if the trans double bonds were reduced preferentially. 

Phthalazine-l,4-diones have been prepared by nucleophilic cleavage of polystyrene-bound phthalimides (Entry 7, Table 15.27). The reaction rate proved to be highly dependent on the solvent used, being low in EtOH but high in DCM. Using DMF as solvent, no phthalazinediones could be isolated [325]. Hexahydropyridazines have been prepared on cross-linked polystyrene in low yields by treatment of support-bound 1-acyloxy-l, 3-dienes with diimide [326]. 

Diels-Alder reactions are, of course, reversible, and the pathway followed for the reverse reaction (2,3 arrows) can sometimes be as telling as the pathway for the forward reaction. The direction in which any pericyclic reaction takes place is determined by thermodynamics, with cycloadditions, like the Diels-Alder reaction, usually taking place to form a ring because two n-bonds on the left are replaced by two Diels-Alder reaction can be made to take place in reverse when the products do not react with each other rapidly, as in the pyrolysis of cyclohexene 2.3 at 600°. It helps if either the diene or the dienophile has some special stabilization not present in the starting material, as in the formation of the aromatic ring in anthracene 2.15 in the synthesis of diimide 2.16 from the adduct 2,14, and in... 

Itsuno developed a chiral binaphthylaluminum chloride to promote the asymmetric Diels-Alder polymerization of a bis(diene) with a diimide, which furnished the corresponding optically active functionalized polymers in high yield [60] (Eq. 8A.36). 

Schotman and co-workers tentatively assigned the new Raman peaks at 1625 and 1592 cm 1 observed during sulfur vulcanisation of squalene, to the formation of conjugated dienes and trienes, respectively [70]. When vulcanisation was carried out in the presence of l,3-di(citraconimidomethyl)benzene, this resulted in a reduced intensity of these two new peaks, corroborating that conjugated dienes and trienes, formed as a result of reversion, react with the diimide. Obviously, the diimide is not an anti-reversion agent in the sense that it prevents reversion, but it is in the sense that it repairs crosslinks when reversion has occurred. 

The reaction of AT-sulfinyl dienophiles with 1,3-dienes yields 3,6-dihydrothia-zine 1-oxides (compare the corresponding reactions with sulfur diimides. Sect. 3.1), which can be ring opened with carbon nucleophiles to yield allylic sulfoxides ready to undergo the ME rearrangement. The seminal paper on this chemistry by Weinreb appeared in 1984 (Scheme 57) [67,140]. 

The initial scission of cyclobutane ring of available pagodane derivative 37 is achieved as a result of homolytic bromination. The tribromide 38, thus formed, underwent facile bromine elimination-fragmentation (and hydrogenolysis of the C-Br bond at the a-methoxycarbonyl center) under the action of metals to form diene 39. Diimide reduction of 39 affected only one double bond and gave product 40, which served as a common precursor for both 35 and 36. The... 

Table 3 Relative Reactivities of Conjugated Dienes Toward Reduction with Diimide ...

Diimide reduction of the major photoproduct 6 gave bicyclo[6.1.0]nonane (8), while base-catalyzed isomerization of 6 provided two components in a 5 1 ratio, identified as bi-cyclo[6.1.0]non-l-ene (9) and cyclonona-1,2-diene... 

A well-studied addition-cure phenolic resin utilizes the Diels-Alder reaction for its preparation. The result is a complex polymer that originates from a diallyl phenol and a diimide (for example, see structures 2 and 3, respectively). Initially, compounds 2 and 3 react across the double bond of the imide ring and the allylic group to generate a diene [see Eq. (6)]. Compound 2 then serves as the dienophile. The polymer forms from the reaction of the diene with 2. The amount of 2 relative to the diene affects the properties of the resulting polymer, as does the cure temperature. Some of these properties will be summarized... 

It was shown that conjugated dienes are more reactive than monoenes in their reduction by diimide ". According to the data of Table 1, conjugation increases the relative reactivity in reduction of dienes (fcjei) compared with the reduction of monoenes, but the more substituted double bond is less reactive. 

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