2016
DOI: 10.1021/acs.orglett.6b02072
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Protecting-Group-Free Total Synthesis of (−)-Lycopodine via Phosphoric Acid Promoted Alkyne Aza-Prins Cyclization

Abstract: A protecting-group-free route for the total synthesis of (-)-lycopodine was demonstrated in only 8 steps from Wade's fawcettimine enone (12 steps from commercial availiable (R)-(+)-pulegone). The key core of this alkaloid was constructed through a phosphoric acid promoted and highly stereocontrolled alkyne aza-Prins cyclization reaction, synchronously establishing the bridged B-ring and the C13 quaternary stereocenter. Importantly, the synthesis further features a new efficient approach for the preparation of … Show more

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Cited by 35 publications
(25 citation statements)
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“…[ 17 ] We commenced our synthesis from the Wade's enone, which was easily prepared in large scale in 4 steps from R ‐pulegone (Scheme 7). [ 18 ] Michael addition of propargylindium reagent to Wade's enone followed by an acid‐promoted one‐pot translactamation/condensation reaction delivered two bicyclic alkyne‐ enamides 30 in high yields. After an extensive screening of the optimal acid promoters, the key aza ‐Prins cyclization of 30 smoothly proceeded to give the desired tricyclic compounds 33a and 33b in 90% and 96% yields, respectively, under the weaker Brōnsted acids conditions (HCO 2 H/85% H 3 PO 4 , 1 : 1).…”
Section: Total Syntheses Of Lycopodium Alkaloidsmentioning
confidence: 99%
“…[ 17 ] We commenced our synthesis from the Wade's enone, which was easily prepared in large scale in 4 steps from R ‐pulegone (Scheme 7). [ 18 ] Michael addition of propargylindium reagent to Wade's enone followed by an acid‐promoted one‐pot translactamation/condensation reaction delivered two bicyclic alkyne‐ enamides 30 in high yields. After an extensive screening of the optimal acid promoters, the key aza ‐Prins cyclization of 30 smoothly proceeded to give the desired tricyclic compounds 33a and 33b in 90% and 96% yields, respectively, under the weaker Brōnsted acids conditions (HCO 2 H/85% H 3 PO 4 , 1 : 1).…”
Section: Total Syntheses Of Lycopodium Alkaloidsmentioning
confidence: 99%
“…She and co-workers used the alkynyl aza-Prins cyclization as the key step of their total synthesis of (-)-lycopodine (135) (Scheme 30). 56 Beginning with 132, the aza-Prins reaction is initiated under aqueous acidic conditions by protonation of the enamide moiety to reveal the N-acyliminium electrophile 133. This species then undergoes distal cyclization by the nucleophilic alkyne.…”
Section: Reviewmentioning
confidence: 99%
“…Very recently She's group succeeded in the asymmetric total synthesis of two Lycopodium alkaloids, with tetracyclic cores: (–)‐lycopodine ( 140 ) and (–)‐lycospidine A ( 141 ), which have been used in Chinese folk medicine as analgesics, for example . The main difference between the core structures of the two natural products resides in the A ring: in (–)‐lycopodine this is a six‐membered ring, whereas in (–)‐lycospidine A it is five‐membered (Scheme ).…”
Section: Synthesis Of Natural Products and Bioactive Moleculesmentioning
confidence: 99%