Electrophilic cyclization of amino ketals 14a and 14b with 6 M HCl at 23 degrees C, followed by oxidation with air in 6 M HCl at 100 degrees C, gave tetrahydrophenanthridines 16a and 16b, respectively, which were transformed into the pyrrolophenanthridinium salts 1a and 1b. Compound 1b was shown to be the correct structure of the Narcissus pallidulus constituent, roserine.
Electrophilic cyclization of amino ketals 14a and 14b with 6 M HCl at 23 degrees C, followed by oxidation with air in 6 M HCl at 100 degrees C, gave tetrahydrophenanthridines 16a and 16b, respectively, which were transformed into the pyrrolophenanthridinium salts 1a and 1b. Compound 1b was shown to be the correct structure of the Narcissus pallidulus constituent, roserine.
Electrophilic cyclization of amino ketals 14a and 14b with 6 M HCl at 23 degrees C, followed by oxidation with air in 6 M HCl at 100 degrees C, gave tetrahydrophenanthridines 16a and 16b, respectively, which were transformed into the pyrrolophenanthridinium salts 1a and 1b. Compound 1b was shown to be the correct structure of the Narcissus pallidulus constituent, roserine.