Amine 1-nitro-1-alkene

Scott Denmark of the University of Illinois reports (J. Org. Chem. 68 8015,2003) a hetero intramolecular Diel-Alder reaction of a nitro alkene 5, followed by intramolecular dipolar cycloaddition of the resulting nitronate 6, to give the tricycle 7. Raney nickel reduction effected cleavage of the N-0 bonds and reductive amination of the liberated aldehyde, to give, after acetylation, the angularly substituted cis-decalin 8. 

Nitroalkenes (see 30) are easily made from nitro-alkanes and aldehydes and take part as dieno-philes in Diels-Alder reactions (chapter 17). The products can, as usual, be converted into amines or ketones. The stimulant fencamfamin 39 disconnects to the obvious Diels-Alder adduct 41 from cyelopentadiene 42 and the nitro-alkene 43. 

The dilithio derivative of an iV,N-dihydroxyenamine RCH=CHN(OLi)2 ( super-enamine ) has been proposed. This species may be also considered as a reduced form of the nitro-alkene RCH=CHN02507. Heating of secondary amines with ketals yields enamines95,508-511 (equation 32). 

The versatility of nitro-compounds in terms of their synthesis and reactivity has ensured they remain as popular amine precursors. In particular, the action of various reducing agents upon nitro-alkenes has been studied (vide infra) with reduction to primary... 

Enders described a fascinating organocatalytic one-pot asymmetric synthesis of tricyclic compounds using a triple-cascade/Diels-Alder reaction sequence. Combination of dieneal 110 with enal 111 and nitro alkene 112 in the presence of a chiral amine catalyst results in a Michael/Michael/aldol condensation sequence to yield cycloaddition precursor 113. Cooling the reaction mixture and addition of a Lewis acid promotes the desired intramolecular Diels-Alder reaction to selectively afford the highly functionalized tricyclic target 114. ... 

Nitro-alkenes are good Michael acceptors and the nitro group can be reduced to an amine. For the production of amino acids, this method requires that the nucleophile contain a carbonyl moiety. When nitroethene was treated with dimethyl malonate under basic conditions. 3.70 was obtained.3 As in other systems of this type, catalytic hydrogenation of 3.70 led to an amino-ester that cyclized to 2-pyrro-lidinone derivative 3.71). Acid hydrolysis (which was accompanied by decarboxylation) gave 4-aminobutanoic acid (5.48).37.29... 

One year later, Rahaman et al. reported a cascade reaction of aldehyde and nitro alkanes for the synthesis of functionalized y-nitro aldehydes with high reactivity [33], Generation of the intermediate nitro alkenes involved cooperative secondary amine/hydrogen bonding-promoted condensation of nitromethane and aldehydes. Consequently, the newly formed nitro alkenes promptly participated in the next cycle cocatalyzed by the two catalysts (Scheme 9.37). 

As another example of nitrene formation, the reaction of o-nitrostilbene (96) with CO in the presence of SnCU affords 2-phenylindole (97). The reaction is explained by nitrene formation by deoxygenation of the nitro group with CO, followed by the addition of the nitrene to alkene. Similarly, the 2//-indazole derivative 99 was prepared by reductive cyclization of the A-(2-nitrobenzyli-dene)amine 98[89]. 

In general, peroxomonosulfates have fewer uses in organic chemistry than peroxodisulfates. However, the triple salt is used for oxidizing ketones (qv) to dioxiranes (7) (71,72), which in turn are useful oxidants in organic chemistry. Acetone in water is oxidized by triple salt to dimethyldioxirane, which in turn oxidizes alkenes to epoxides, polycycHc aromatic hydrocarbons to oxides and diones, amines to nitro compounds, sulfides to sulfoxides, phosphines to phosphine oxides, and alkanes to alcohols or carbonyl compounds. 

Secondary amines can be added to certain nonactivated alkenes if palladium(II) complexes are used as catalysts The complexation lowers the electron density of the double bond, facilitating nucleophilic attack. Markovnikov orientation is observed and the addition is anti An intramolecular addition to an alkyne unit in the presence of a palladium compound, generated a tetrahydropyridine, and a related addition to an allene is known.Amines add to allenes in the presence of a catalytic amount of CuBr " or palladium compounds.Molybdenum complexes have also been used in the addition of aniline to alkenes. Reduction of nitro compounds in the presence of rhodium catalysts, in the presence of alkenes, CO and H2, leads to an amine unit adding to the alkene moiety. An intramolecular addition of an amine unit to an alkene to form a pyrrolidine was reported using a lanthanide reagent. 

The addition of alkoxides to 2-nitro-l-phenylthio-l-alkenes affords P-nitro-aldehyde acetals.276 The reaction of the same nitroalkenes with amines gives nitroenamines.270 They are important intermediates for organic synthesis and are generally prepared by the reaction of nitroalkanes with triethylorthoformate in the presence of alcohols or secondary amines.2"1 0 The methods of Eqs. 4.20 and 4.21 have some merits over the conventional methods, for variously substituted (3-nitro-aldehydes acetals or nitroenamines are readily prepared by these methods. 

Burk et al. showed the enantioselective hydrogenation of a broad range of N-acylhydrazones 146 to occur readily with [Et-DuPhos Rh(COD)]OTf [14]. The reaction was found to be extremely chemoselective, with little or no reduction of alkenes, alkynes, ketones, aldehydes, esters, nitriles, imines, carbon-halogen, or nitro groups occurring. Excellent enantioselectivities were achieved (88-97% ee) at reasonable rates (TOF up to 500 h ) under very mild conditions (4 bar H2, 20°C). The products from these reactions could be easily converted into chiral amines or a-amino acids by cleavage of the N-N bond with samarium diiodide. 

Divalent chromium reduces triple bonds to double bonds (trans where applicable) [195], enediones to diones [196], epoxides to alkenes [192] and aromatic nitroso, nitro and azoxy compounds to amines [190], deoxygenates amine oxides [191], and replaces halogens by hydrogen [197,198],... 

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