Alkenes nitrogen addition

This review is written to cover the needs of synthetic chemists with interests in oxidizing alkenes by addition of nitrogenous substituents. Whilst some aspects have been covered in previous reviews (noted in the text), most notably in the Tetrahedron Report No. 144, Amination of Alkenes and prior reviews on aziridines and nitrenes, the present review is the fust conq>ilation of references to the whole range of these particular bond-forming processes. A review by Whitham provides a useful general introduction to reaction mechanisms of additions to alkenes in greater detail than can be covered here. The oxidation requirement excludes from the scope the additions of N H and most additions of N + Metal or N + C. Hence, unmodified Michael and Ritter reactions are excluded. These topics are mostly covered in Volume 4 of the present series. 

The compound B formed must be, then, either a tertiary amine or an alkene. Its molecular formula does not contain "N (for nitrogen), which means it must be an alkene. In addition, the fact that B was cleaved into two products by ozone, acid, and zinc indicates the present of a double bond, for these reagents are the basis for the ozonolysis reaction, which cleaves compounds with double bonds into aldehydes and ketones. 

When it is irradiated or exposed to catalytic amounts of copper, diazomethane evolves nitrogen to generate the reactive carbene methylene, H2C Methylene reacts with alkenes by addition to form cyclopropanes stereospecificaUy (Section 12-9). 

The best procedures for 3-vinylation or 3-arylation of the indole ring involve palladium intermediates. Vinylations can be done by Heck reactions starting with 3-halo or 3-sulfonyloxyindoles. Under the standard conditions the active catalyst is a Pd(0) species which reacts with the indole by oxidative addition. A major con.sideration is the stability of the 3-halo or 3-sulfonyloxyindoles and usually an EW substituent is required on nitrogen. The range of alkenes which have been used successfully is quite broad and includes examples with both ER and EW substituents. Examples are given in Table 11.3. An alkene which has received special attention is methyl a-acetamidoacrylate which is useful for introduction of the tryptophan side-chain. This reaction will be discussed further in Chapter 13. 

Aziridines have been prepared stereospecifically by the nucleophilic addition of the nitrogen residue to alkenes <80T73). Introduction of the nitrene is accomplished readily via a Michael-type addition with free diphenylsulfilimine (Scheme 12), and where a chiral sulfilimine is used the chirality is transferred to the aziridine with optical yields in excess of 25%. 

For reactions of A-acyliminium ions with alkenes and alkynes one has to distinguish between A-acyliminium ions locked in an s-trans conformation and those which (can) adopt an s-cis conformation. The former type reacts as a (nitrogen stabilized) carbocation with a C —C multiple bond. Although there are some exceptions, the intramolecular reaction of this type is regarded as an anti addition to the 7t-nucleophile, with (nearly) synchronous bond formation, the conformation of the transition state determining the product configuration. 

Addition of NOCl and other nitrogen compounds to alkenes... 

The suspension may be warmed to dissolve the alkene more rapidly. (E)-Stilbene dissolves completely at ca. 65°. If the suspension is warmed, it must be cooled below 30° before proceeding further to prevent a vigorous reaction when the N-bromo-succinimide is added. The submitters recommend that the warm suspension be cooled under an atmosphere of nitrogen. If a volatile alkene is used, the mixture should be cooled prior to and during the addition of N-bromosuccinimide to prevent losses by evaporation. 

Intramolecular nitrone cycloadditions often require higher temperatures as nitrones react more sluggishly with alkenes than do nitrile oxides and the products contain a substituent on nitrogen which may not be desirable. Conspicuously absent among various nitrones employed earlier have been NH nitrones, which are tautomers of the more stable oximes. However, Grigg et al. [58 a] and Padwa and Norman [58b] have demonstrated that under certain conditions oximes can undergo addition to electron deficient olefins as Michael acceptors, followed by cycloadditions to multiple bonds. We found that intramolecular oxime-olefin cycloaddition (lOOC) can occur thermally via an H-nitrone and lead to stereospecific introduction of two or more stereocenters. This is an excellent procedure for the stereoselective introduction of amino alcohol functionality via N-0 bond cleavage. 

Violent explosions which occurred at —100 to —180°C in ammonia synthesis gas units were traced to the formation of explosive addition products of dienes and oxides of nitrogen, produced from interaction of nitrogen oxide and oxygen. Laboratory experiments showed that the addition products from 1,3-butadiene or cyclopentadiene formed rapidly at about — 150°C, and ignited or exploded on warming to —35 to — 15°C. The unconjugated propadiene, and alkenes or acetylene reacted slowly and the products did not ignite until +30 to +50°C [1], This type of derivative ( pseudo-nitrosite ) was formerly used (Wallach) to characterise terpene hydrocarbons. Further comments were made later [2],... 

The intramolecular Michael-type addition of the nitrogen atom of piperidines to activated alkenes located at a C(2)-side chain is a quite common way of access to the quinolizidine system. Some examples are given below. 

The synthesis of nitrogen containing heterocyclic systems by photocylo-addition processes is virtually limited to examples involving [ 2 + 2] cycloaddition of imines, nitriles, and azo compounds. Successful additions are few in number and the requirements for success uncertain. The reactions do not proceed with the facility with which carbonyl containing compounds undergo photocycloaddition to alkenes to give oxetans, and various explanations have been advanced to account for this observed lack of reactivity.226... 

An example of intramolecular addition of an azo group to an alkene has been described 233 irradiation of azoalkene 280 affords an almost quantitative yield of the diazetidine 281 with no competing elimination of nitrogen. An analogous cycloaddition is thought to be implicated in the photoreaction of azobenzene with diketene.234... 

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