Amination of alkenes

Since the review by Lattes et al. on the amination of alkenes in 1983 [18] and our first review on the catalytic amination of monoolefins in 1989 [19], several review articles have appeared in the literature [13, 14, 17, 20-23]. The present review corresponds to an analysis of literature data up to the end of 1999. 

Entries 5 to 7 are examples of oxidation of boranes to the carbonyl level. In Entry 5, chromic acid was used to obtain a ketone. Entry 6 shows 5 mol % tetrapropylam-monium perruthenate with Af-methylmorpholine-lV-oxide as the stoichiometric oxidant converting the borane directly to a ketone. Aldehydes were obtained from terminal alkenes using this reagent combination. Pyridinium chlorochromate (Entry 7) can also be used to obtain aldehydes. Entries 8 and 9 illustrate methods for amination of alkenes via boranes. Entries 10 and 11 illustrate the preparation of halides. 

While the Mori-Ban indole synthesis is catalyzed by a Pd(0) species, the Hegedus indole synthesis is catalyzed by a Pd(II) complex. In addition, the Mori-Ban indole synthesis is accomplished via a Pd-catalyzed vinylation (a Heck recation), whereas the Hegedus indole synthesis established the pyrrole ring via a Pd(II)-catalyzed amination (a Wacker-type process). Hegedus conducted the Pd-induced amination of alkenes [430] to an intramolecular version leading to indoles from o-allylanilines and o-vinylanilines [291-293, 295, 250, 251]. Three of the original examples from the work of Hegedus are shown below. 

E. Amination of Alkenes with Chiral Borohydride Reagents. 117... 

Sulfonylhydroxylamines and hydroxylamine O-sulfonic acid have found wide apph-cation in synthesis of amines from achiral or chiral organoboranes and boronate esters and the hydroboration-amination methodology is successfully used for direct amination of alkenes. 0-Sulfonyloximes were also found to be good reagents for synthesis of amines from organomagnesium, -copper and -zinc reagents. 

Palladium-catalyzed addition of oxygen nucleophiles to alkenes dates back to the Wacker process and acetoxylation of ethylene (Sects. 1 and 2). In contrast, catalytic methods for intermolecular oxidative amination of alkenes (i.e., aza-Wacker reactions) have been identified only recently. Both O2 and BQ have been used as oxidants in these reactions. 

A sequential use of two pericyclic reactions involving sulfur compounds is also implied in a general allylic amination of alkenes with Kresze s reagent, 7V,A -bis(methoxycarbonyl)suIfurdiimide (8). A [2,3] sigmatropy, following an ene reaction of the S-allyl sulfinamidine (9) intermediary formed, affords the diamino sulfane (10), easily converted to the carbamate (11) and then to the amine (12) or (13) [511]. The reactions are featured with 2-methyl-2-butene as the alkene to be functionalized. They are described in Organic Syntheses [512]. 

Imido selenium compounds Se(NR)2, where R = Bu or Ts, were first noted to give allylic amination of alkenes and alkynes.232 Formally the NR function is inserted into the allylic C—H bond yielding the C—NHR moiety. Related reactivity was also found for the sulfur imides, S(NR)2.233 Reactions between 1,3-dienes and Se(NTs)2 give [4 + 2] adducts which, in the presence of TsNH2, react to generate 1,2-disulfonamides.234... 

Yamashita, T., Itagawa, J., Sakamoto, D., Nakagawa, Y., Matsumoto, J., Shiragami, T., and Yasuda, M. (2007) Redox-photo-sensitized amination of alkenes and alkadienes with ammonia and alkyl-amines. Tetrahedron, 63, 374—380. 

Nucleophilic amination of alkenes functionalized by an allylic C-X (x = heteroatoms, halides) as outlined in Eq. (1) is a simple and direct procedure for the synthesis of allyl amines, since very efficient methods for the selective allylic functionalization of alkenes are available. 

An attractive procedure for allylic amination is the direct electrophilic amination of alkenes. The single-step procedure allows a convenient allylic functionalization, which is an important part of this amination chemistry. However, compared to the nucleophilic amination of functionalized alkenes, the electrophilic amination of nonfunctionalized alkenes is much more complex, both from a synthetic and mechanistic point of view. 

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. 

Allylic Amination of Alkenes and Silyl Enol Ethers by Selenodiimides... 

Muller TE, Beller M. Metal-initiated amination of alkenes and alkynes. Chem. Rev. 1998 98 675-703. 

Amination. Copper(II) triflate is a good catalyst for amination of alkenes (using chloramine-T to give aziridines) and at benzylic and allylic positions (using t-BuOOCONHTs). ... 

Earlier, a reference was made to the hydration of o-hydroxy-a-phenylstyrene and the amination of alkenes. The mechanism of these reactions has been probed in some depth. It is clear that proton transfer takes place on the irradiation of such systems and the transfer takes place to the alkenyl carbon and results in the formation of a quinonemethide such as 53. Early work on the results of irradiation of o-hydroxybenzyl alcohol showed that a quinonemethide was formed. In the absence of other trapping agents phenol/formaldehyde resin-like materials were formed. Minor products such as 54 and 55 were also produced... 

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