Ferruginine

BF(3)-Induced rearrangement of aziridino cyclopropanes derived from 2-phenylsulfonyl 1,3-dienes. Application to the total synthesis of (+/-)-ferruginine.[Pubmed:11112563]

J Org Chem. 2000 Dec 15;65(25):8454-7.

Total synthesis of the alkaloid (+/-)-Ferruginine (1) has been developed via the 2-phenylsulfonyl 1,3-diene approach. BF(3)-induced rearrangement of the N-protected cyclohexane aziridino cyclopropane 8, derived from its corresponding epoxy cyclopropane, afforded the desired tropane alkaloid skeleton 9 in good yield. Michael addition of nitroethane (as an acyl anion equivalent) and transformation of the nitro group of the adduct 10 to a keto function gave 11. Elimination of benzenesulfinic acid and subsequent replacement of the tosyl group by a methyl group afforded the title compound 1.

Total synthesis of (-)-cocaine and (-)-ferruginine.[Pubmed:21391709]

J Org Chem. 2011 Apr 15;76(8):2694-700.

Total synthesis of tropane alkaloids (-)-cocaine and (-)-Ferruginine were accomplished in nine steps each and in 55% and 46% overall yields, respectively, starting from the known Betti base derivative (+)-(7aR,10R,12S)-10-(1H-benzotriazol-1-yl)-7a,8,9,10-tetrahydro-12-phenyl-12H-na phtho[1,2-e]pyrrolo[2,1-b][1,3]oxazine. In this novel route, RCM reaction and 1,3-dipolar cycloaddition were employed as key steps for the enantioselective construction of tropane skeleton and the regioselective introduction of 3-bromo-2-isoxazoline ring as masked cis-2,3-disubstituents. To obtain the desired precursor (2S,5R)-2-allyl-5-vinylpyrrolidine for RCM reaction, we developed a general and practical method for the preparation of enantiopure cis-2,5-disubstituted pyrrolidines bearing alkene- and/or alkyne-containing substituents. We also offered two highly efficient pathways for the conversion of the 3-bromo-2-isoxazoline ring into the desired cis-2,3-disubstituted groups in (-)-cocaine and (-)-Ferruginine.

Synthesis and evaluation of diazine containing bioisosteres of (-)-ferruginine as ligands for nicotinic acetylcholine receptors.[Pubmed:11557356]

Bioorg Med Chem. 2001 Oct;9(10):2683-91.

In this structure-affinity relationship (SAFIR) study, the bioisosteric potential of diazines in the field of Ferruginine-type nAChR ligands was investigated. Novel enantiopure analogues of (-)-Ferruginine (3) such as 6-8 were synthesized utilizing enantiomerically pure N-protected (+)-2-tropanone 9 from the 'chiral pool' as versatile chiral building block and a palladium-catalyzed Stille cross-coupling of the tributylstannyl diazines 12, 14 and 16 with the vinyl triflate 11 of (+)-2-tropanone 9. The structures of the novel diazine analogues 6-8 of (-)-Ferruginine (3) were assigned on the basis of spectral data, that of ligand 7 being additionally verified by X-ray crystallography. The bioisosteric replacement of the acetyl moiety as structural part of the lead compound 3 with the pyridazine, pyrimidine and pyrazine nucleus resulted in ligands with high to moderate affinity for the central alpha4beta2 and remarkably low affinity for the alpha7* nAChR subtypes. Among the compounds synthesized and tested, 7 was the most active one with K(i)=3.7 nM (alpha4beta2). Compared with the lead 3, this value represents a 30-fold improvement in the affinity for the alpha4beta2 subtype combined with a substantially improved selectivity ratio between the alpha4beta2 and alpha7* subtypes.