The Conversion of Dihydrolycorine to (-)-α-Lycorane
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In this article, the steric structure of dihydrolycorine was considered, in view of the sequence of reactions used in this transformation, to be that of the ring-system.Abstract:
Treatment of dihydrolycorine (I) with phosphoryl chloride under mild conditions yielded a chlorohydrin (V). Reduction of this hydrin with zinc in acetic acid followed by reduction with hydrogen and platinum oxide afforded (-)-α-lycorane (VII), the steric structure of which was considered, in view of the sequence of reactions used in this transformation, to be that of the ring-system of dihydrolycorine.read more
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Journal ArticleDOI
Total synthesis of (±)-α-lycorane and 4,5-dehydroanhydrolycorine
James H. Rigby,Mary E. Mateo +1 more
TL;DR: The total synthesis of (±)-α-lycorane and dehydroanhydrolycorine are described in this article, where the key intermediate in both approaches is the hydroindolone 5, prepared from the [1+4] cycloaddition reaction of 1-isocyanatocyclohexene and cyclohexyl isocyanide.
Journal ArticleDOI
Total synthesis of (+/-)-alpha- and beta-lycoranes by sequential chemoselective conjugate addition-stereoselective nitro-Michael cyclization of an omega-nitro-alpha,beta,psi,omega-unsaturated ester.
Tomohisa Yasuhara,Katsumi Nishimura,Mitsuaki Yamashita,Naoshi Fukuyama,Ken-ichi Yamada,Osamu Muraoka,Kiyoshi Tomioka +6 more
TL;DR: The 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.
Journal ArticleDOI
γ- And δ-lycorane
TL;DR: In this paper, the configurational structures of α-, β-, γ- and δ-lycorane were established and the configuration of dihydrolycorine was confirmed.
Journal ArticleDOI
Catalytic Asymmetric Hydrogenation of α‐Arylcyclohexanones and Total Synthesis of (−)‐α‐Lycorane
TL;DR: In this paper, an efficient catalytic asymmetric hydrogenation of racemic α-arylcyclohexanones with an ethylene ketal group at the 5-position of the cyclohexane ring via dynamic kinetic resolution has been developed, giving chiral α-ylcorane with two contiguous stereocenters with up to 99% ee and >99:1 cis/trans-selectivity.
Journal ArticleDOI
Efficient synthesis of (±)-γ-lycorane employing stereoselective conjugate addition to nitroolefin
Tomohisa Yasuhara,Emi Osafune,Katsumi Nishimura,Mitsuaki Yamashita,Ken-ichi Yamada,Osamu Muraoka,Kiyoshi Tomioka +6 more
TL;DR: In this paper, the synthesis of γγ-Lycorane 3 was achieved in 52% overall yield via seven steps from 5 by employing the highly stereoselective nitro-Michael cyclization of 5 to 9 and diastereoselectively conjugate addition of aryllithium to a nitroolefin 10 as two key steps.