Asymmetric formal synthesis of (−)-pancracine via catalytic enantioselective C–H amination process

Chiral Dirhodium Catalysts: A New Era for Asymmetric Catalysis

“…Hashimoto and coworkers [50], in 2008 disclosed the first example for the enantioselective amination for an allylic C-H bond of silyl enol ethers 212 derived from cyclic ketones 211 or enones of six-membered-rings by using [(2-nitrophenylsulfonyl)imino]phenyliodinane (213; NsN=IPh) as a nitrogen precursor catalyzed by dirhodium (II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-leucinate] complex 33e [144,145], [Rh 2 (S-TCPTTL) 4 ] which has provided, after desilylation, N-pNs-protected (S)--aminocyclohexanone 215 as a sole product in up to 72% ee (Fig. 32).…”

“…Chiral dirhodium(II) catalysts derived from enantiomerically pure -carboxamidates ligands were initially developed by Doyle and co-workers [7,[32][33][34][35][36][37][38][39][40][41][46][47][48][49][50]. Later on, the range of complexes has been expanded to include a greater diversity of a variety of ligands (73-83) (i.e., Pyrrolidinone, oxazolidinones, imidiazolidinone, and azetidinone) and ligand substituents.…”

Amaryllidaceae and Sceletium alkaloids

“…90 Under the co-catalysis of Pd(PPh 3 ) 4 and CuI, the coupling cyclization of 3,5-dibromo-2-pyrone 103 and aryltin 133 afforded the endo-tertracyclolactone 134 as the major product, which was finally converted into (AE)-galanthamine after a sequence of reactions (Scheme 6). 96 An enantioselective total synthesis of (+)-montabuphine 145 has been achieved starting from the readily available chemoenzymatic metabolite 146. 91 Suzuki coupling between the commercially available aldehyde 135 and the boronic acid tris anhydride 136 gave the aldehyde 137 in 99% yield.…”

One‐Step Stereospecific Strategy for the Construction of the Core Structure of the 5,11‐Methanomorphanthridine Alkaloids in Racemic as well as in Optically Pure Form: Synthesis of (±)‐Pancracine and (±)‐Brunsvigine

“…Most of the asymmetric approaches known for the synthesis of montanine alkaloids are mainly based on chiral-pool strategies except for two recent reports on the formal synthesis of pancracine [17,18] based on organocatalytic approaches. The asymmetric 1,3-dipolar cycloaddition of azomethine ylides to a variety of alkenes has emerged as one of the most powerful strategies for the construction of enantiopure pyrrolidine ring systems.…”

“…Overman, [11] Pearson, [12] Ikeda, [13] Sha, [14] Banwell, [15] Chang, [16] Hashimoto [17] and Pansare [18] and their co-workers all used precursors of type 9 in their respective elaborations of these alkaloids. However, in all these strategies, the syntheses were elaborated from a precursor having the desired stereochemistry at C-4a and C-11a and relative disposition of the methylene bridge of 8, which involved its construction in a stepwise manner.…”