Domino nitro-Michael additions

Intermolecular Domino Nitro-Michael Additions of C-Nucleophiles... 

A number of highly efficient asymmetric domino nitro-Michael additions of C-nucleophiles catalysed by organocatalysts were described in 2008. One of the most employed organocatalysts for these types of reactions is diphenylprolinol silyl ether. This catalyst was used by Hong et al. to develop a highly diastereo-and enantioselective domino reaction occurring between 7-oxohept-2-enoate and nitroalkenes (Scheme 1.61). ° The reaction afforded highly functionalised... 

Chiral secondary amines are another important class of privileged functional component in dual organocatalysis that has been widely used in asymmetric catalysis [39]. For example, in 2008, Cordova et al. [40] reported the combinational use of (S)-diphenylprolinol TMS ether (127) and Br0nsted base DABCO (128) as dual organocatalysts to promote the asymmetric domino double Michael addition reaction (nitro-Michael/Michael reaction) of 5-nitropentenoate (125) to a,(i-unsaturated aldehydes (Scheme 43.26), which gave the corresponding nitrogen-,... 

The final group of threefold anionic domino processes described here includes transformations with an initiating elimination step which is either followed by two Michael additions or by substitutions. Thus, reaction of protected nitro alcohol 2-... 

In this domino process, first, the nitro group gets reduced to give an amine moiety, which then undergoes a Michael addition to afford an unsaturated ester the final step is the elimination of water to yield 117 [69]. Recently, Banwell et al. applied a domino nitroarene reduction protocol for the total synthesis of 1,5-methanoazocino[4,3-f)]indole 118 framework of the uleine and strychnos alkaloids (Scheme 9.24). Pd/C reduction of nitroarene 119 in methanolic solution afforded annulated indole 120, which presumably arose from the reduction of both nitro and the carbon-carbon double bond. Raney-nickel reduction produced the amine analog 121. However, Raney-cobalt reduction resulted in the tetracyclic compound... 

Enamine-ActivatedDouble 06-Functionalization Enders et al. reported an organocatalytic domino Michael addition/alkylation reaction between aliphatic aldehydes and ( )-5-iodo-l-nitropent-l-ene 33 involving enamine-enamine activation (Scheme 1.10) [12], This process is highly stereoselective and leads to the y-nitro aldehydes, which contain an all-carbon-substituted quaternary stereo-genic center. 

In addition, a four-component domino Michael/nitro-Mannich/lactamization reaction was recently developed by Dixon et al. [286]. It occurred between a... 

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