Diolefin, heterocyclic

Finally, it must be mentioned that phenylselenation of some diolefins may provide a suitable method for the construction of heterocycles containing two phenylseleno groups. For instance, 3 reacts142 with lV-(phenylseleno)phthalimide (NPSP) in the presence of cyanamide (FENCN) to give the regioisomeric 9-azabicyclo[3.3.1]- and 9-azabicyclo [4.2.1]-nonanes, 173 and 174, as the result of a combined process of inter- and intramolecular nucleophilic addition of cyanamide (equation 140). 

Gums Conjugated diolefins and other olefinic compounds formed during catalytic and thermal cracking processes heterocyclic compounds present in fuel can also initiate gum formation... 

Tellurium tetrachloride and tellurium tetrabromide added to 1,5-diolefins and 1,6-diolefins with formation of heterocyclic tellurium compounds3-5. 

Two reviews of isomerization reactions should be referred to as sources of information on Russian researches in the field. The book by Petrov (291) on isomerization of paraffins, olefins, diolefins, and acetylenes with up to 34 carbon atoms gives information based on Russian and non-Russian researches and was written by an author who has carried out with co-workers numerous studies of isomerization of olefins in the presence of various catalysts. The review by Danilov (55) was confined to Russian contributions to the field of isomerization during the period of 1917-1947 and covers isomerization of hydrocarbons of all classes, their halogenated derivatives, oxygenated compounds and heterocyclics. In view of these detailed publications, the discussion below is limited to highlights of the field. 

Since the criss-cross cycloaddition reaction is a sequence of two [3 + 2] cycloaddition steps, the reaction of hexafluoroacetone azine with a,a>-diolefins offers access to a new class of trifluoromethyl-substituted heterocyclic macromolecules. Polymers with interesting structures and properties become available by criss-cross polymerization (88MI3 89MI2 90MI2). 

The reactive species that initiate free-radical oxidation are present in trace amounts. Extensive studies (11) of the autoxidation mechanism have clearly established that the most reactive materials are thiols and disulfides, heterocyclic nitrogen compounds, diolefins, furans, and certain aromatic-olefin compounds. Because free-radical formation is accelerated by metal ions of copper, cobalt, and even iron (12), the presence of metals further complicates the control of oxidation. It is difficult to avoid some metals, particularly iron, in fuel systems. 

As previously described, RCM is a powerful tool for the preparation of useful carbo- and heterocyclic intermediates. Almost all of the recent RCM reactions have been performed homogeneously with well-defined metal carbene complexes as catalysts. An example of the use of a heterogeneous catalyst in RCM is the synthesis of hydroazulenes such as 6 via RCM of highly functionalized diolefins (Eq. 17) catalyzed by CH3Re03/Si0i-Al703 and with heating under reflux at 80 °C [41]. 

Dienes have been assembled to react in MOFs. In particular, Eddaoudi and coworkers employed Cu(II) ions to assemble the anion of the heterocyclic diolefin cheUdonic acid (cdo) for a donble [2-1-2] photodimerization (Fignre 17). The dicarboxylate reacted in a ID polymer via a SCSC transformation to give an unusual cagelike photodimer. 

In addition to diolefins, there are other bifunctional compounds that will form boron heterocyclics under analogous reaction conditions. For example, the triallyl ester of orthoboric acid reacts with trialkylamine-borane in the presence of trialkylboranes to give B-alkyl-l,2-oxaborolane (XXXVIII) (5). 

Intramolecular addition of a nucleophile to a double bond can be induced by PhSeX this method forms the basis of a useful preparation of various cyclic compounds, and further examples of this procedure have appeared. In the first, the alkenylketones (141) and (142) are cyclized to the enol ether (143) and the ketone (144), respectively. " 7V-Phenylselenophthalimide can be used for the transformation (141) -> (143), but is unsuitable for the conversion (142) - (144) in this case PhS SbF6 (PF6 ) must be used. Diolefins are readily converted to the diphenylseleno-cyclic ethers (145), and amino-olefins (146) are easily cyclized to the corresponding nitrogen heterocycles by phenylselenyl chloride. ... 

Also, generation of the heterocyclic strained allene 217 in diolefins 218 used as solvents affords the cycloadducts 219 and 220... 

The group connecting the double bonds, X, can be composed of carbon atoms, carbon and heteroatoms, and heteroatoms. Diolefins can also be copolymerized with monoolefins via the same scheme. Cyclopolymerization is a powerful tool in synthetic polymer chemistry. It allows the preparation of carbocyclic ring-containing polymers as well as several classes of heterocyclic ring-containing polymers. The scope of this reaction has been reviewed several times (4,19,20,23, 77, 91,100,123,143,168). 

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