97185-46-1Relevant academic research and scientific papers
Mn(III)/Cu(II)-mediated oxidative radical cyclization of α-(methylthio)acetamides leading to erythrinanes
Chikaoka, Shiho,Toyao, Atsushi,Ogasawara, Mizuho,Tamura, Osamu,Ishibashi, Hiroyuki
, p. 312 - 318 (2007/10/03)
Treatment of N-[2-(3,4-dimethoxyphenyl)ethyl]-α-(methylthio)acetamide 3 with Mn(OAc)3 in the presence of Cu(Oac)2 gave tetrahydroindol-2-one 4, which then cyclized with Mn(Oac)3 to give 4-acetoxyerythrinane 5. A similar reaction of the 3,4-methylenedioxyphenyl congener 8 also gave tetrahydroindol-2-one 9, which, however, gave only a trace amount of the Mn(OAc)3-mediated cyclization product 11 and afforded the oxidation product 10. On the basis of these results, formation of 5 from 4 was thought to proceed via nucleophilic attack of the pyrrole ring on the cation-radical IX, generated by a single electron-transfer reaction of the acetoxy-substituted intermediate V. Treatment of compound 16 with Mn(OAc)3/Cu(OAc)2 gave no erythrinane derivative with recovery of the starting material, indicating that the presence of a methylthio group of 4 is essential for effecting the formation of erythrinane 5. On the other hand, treatment of 3 with Mn(OAc)3 using Cu(OTf)2 as an additive in place of Cu(OAc)2 gave another erythrinane 17. This method was applied to a formal synthesis of 3-demethoxyerythratidinone (20), a naturally occurring Erythrina alkaloid.
One-step Synthesis of the Erythrinane Skeleton by Acid-promoted Double Cyclization of N-(Cyclohex-1-enyl)-N--α-(mehylsulphinyl)acetamide and its Derivatives
Ishibashi, Hiroyuki,Sato, Kazumi,Ikeda, Masazumi,Maeda, Hiroshi,Akai, Shuji,Tamura, Yasumitsu
, p. 605 - 610 (2007/10/02)
On being heated with toluene-p-sulphonic acid, N-(cyclohex-1-enyl)-N--α-(methylsulphinyl)acetamide (8) underwent double cyclization to give the erythrinane derivative (11), which was converted into the amide (13) by reduction with Raney nickel and into the enamide (14) by thermolysis of the corresponding sulphoxide.The double cyclization of the sulphoxide (18) gave a stereoisomeric mixture of the ether products (19a) and (19b).On treatment with Raney nickel, either (19a) or (19b) afforded a mixture of the alcohols (20a) and (20b), each o f which was oxidized with chromium trioxide-pyridine to give the same ketone (21).The sulphoxide (25) also cyclized to afford two products (26) and (27), but in low yields, which were desulphurized with Raney nickel to give the erythrinones (28) and (29), respectively.
ACID-CATALYZED CYCLIZATIONS OF N-VINYL-α-SULFINYLACETAMIDES A NOVEL SYNTHETIC APPROACH TO ERYTHRINANE
Tamura, Y.,Maeda, H.,Akai, S.,Ishibashi, H.
, p. 2209 - 2212 (2007/10/02)
Under the Pummerer reaction conditions, N-(1-cyclohexenyl)-N-methyl-α-(methylsulfinyl)acetamide (7a) cyclized in a 5-endo trigonal fashion through the intermediary cation (8) to give the tetrahydro-4H-oxindole (10).The reaction was successively applied to a novel synthesis of erythrinane skeleton.
