Reaction of 1-Benzylindole-2,3-dicarboxylic Anhydride with 3-Bromo-4-lithiopyridine: Formal Synthesis of Ellipticine

Regioselective Intramolecular Reactions of 2-Indolylacyl Radicals with Pyridines: A Direct Synthetic Entry to Ellipticine Quinones

“…As expected, ellipticine quinones 16a , 16b , and 16d showed physical and spectroscopic data identical to those previously described. ,, Because both 16b ,, and 16d 21 were transformed into ellipticine, the synthesis reported here constitutes a formal synthesis of this natural product.…”

“…To our delight, 2-indolylacyl radicals derived from N -methyl selenoesters 15a and 15b (entries 1 and 2) efficiently underwent regioselective cyclization upon the 4-position of the pyridine ring and, after the in situ oxidation at the interannular methylene group, gave the known ellipticine quinones 16a and 16b , in 60 and 42% yield, respectively. Only minor amounts of regioisomers 17a (5%) and 17b (8%) were formed.…”

Isolation and Synthesis of Biologically Active Carbazole Alkaloids

“…Cyclization of 936 with 10% hydrochloric acid provided ellipticine (806) in 87% yield (Scheme 240). 599In 1998, Miki and his group reported a formal synthesis of ellipticine by reaction of the anhydride 931 with 3-bromo-4-lithiopyridine and subsequent transformation to the intermediate 6-benzyl-6Hpyrido[4,3-b]carbazole-5,11-quinone 600.…”

Synthesis of ellipticine by reaction of 1-(4-methoxybenzyl)indole-2,3-dicarboxylic anhydride with (3-bromo-4-pyridyl)triisopropoxytitanium

“…Reaction of 1-benzylindole-2,3-dicarboxylic anhydride 1 6 with 3-bromo-4-lithiopyridine (2, M = Li) in THF at Ϫ96 ЊC gave 1-benzyl-2-(3-bromoisonicotinoyl)indole-3-carboxylic acid 3 in 42% yield (Scheme 1). 5 Many attempts to obtain 3 under various conditions were less than satisfactory (Table 1 entry 1, 2). However, treatment of 1 with (3-bromo-4-pyridyl)triisopropoxytitanium (2, M = Ti(OPr-i) 3 ) 7 afforded 3 in 86% yield (Table 1, entry 3,4).…”