Total Synthesis of (±)-α- and β-Lycoranes by Sequential Chemoselective Conjugate Addition−Stereoselective Nitro-Michael Cyclization of an ω-Nitro-α,β,ψ,ω-unsaturated Ester

Abstract

[reaction: see text] An omega-nitro-alpha,beta,psi,omega-unsaturated ester underwent a chemoselective conjugate addition of a nitroolefin moiety with aryllithium to produce a psi-aryl-omega-nitro-alpha,beta-unsaturated ester, which was then stereoselectively cyclized by intramolecular nitro-Michael reaction giving a functionalized cyclohexane applicable to the total synthesis of (+/-)-alpha- and beta-lycoranes.

Chapter 3 Chemical and Biological Aspects of Narcissus Alkaloids

“…Tomioka described a chemoselective conju gate addition -nitro Michael reaction sequence to prepare aand b-lycoranes in their racemic form (281). A 2-arylcyclo hexanone was regio-and stereoselectively added to nitroethylene to access the octahydroindole core present in the alkaloids.…”

Synthesis and theoretical analysis of interaction from an adamantane-steroid derivative with both COX-1 and COX-2

“…It is important to mention that only Pro 35 (red) could act in a similar form with both 4 and indomethacin. Other theoretical (Table 4) results showed a similar interaction between both rofecoxib and compound 4 with some Ser 23 , GLn 27 and Tyr 40 amino acid residues (red) of COX-2 (3LN1). All these data suggest that there are several differences between the interactions of compound 4 with either COX-1 or COX-2 enzymes could be translated as a different biological activity.…”

“…Several nitro derivatives have prepared using some reagents such as Fe(NO 2 ) 3 [25], sodium hydride [26], aryllithium [27], Iodine(III) [28] and others. In this study a bis-steroid-tetracyclodione derivative was synthesized; the first stage involved the reaction of ethinylestradiol with the nitric acid/anhydride acetic system ( Figure 1).…”

Nitroalkenes as Amination Tools

“…This approach forms the basis for some syntheses of the natural alkaloids lycoranes, promising drug candidates for treatment of Alzheimer ' s disease. Treatment of the nitroalkene 118 with the arylithium reagent 119 results in the exclusive attack at the nitroolefi n moiety (Scheme 3.69 ) [140] .…”