Patent ID: 8921556

Claim:
A method for N-demethylating a compound of formula (6) comprising contacting the compound of formula (6) with a compound of formula (2) in a solvent to provide a compound of formula (7) wherein the solvent comprises a tertiary alcohol; the 7,8-bond is a single bond or a double bond; R 9 and R 11 are each independently selected from the group consisting of —OH, —H, and —OR 15 ; R 9′ and R 11′ are each independently selected from the group consisting of —OH, —H, —OR 15 , and —OC(O)OR 4 ; R 10 is selected from the group consisting of ═O, —OH, ═CH 2 , —H, and —OR 15 ; R 10′ is selected from the group consisting of ═O, —OH, ═CH 2 , —H, —OR 15 , and —OC(O)OR 4 ; R 15 is an oxygen protecting group; R 4 is selected from the group consisting of —(C 1 -C 6 )alkyl, —(C 2 -C 6 )alkenyl, —(C 2 -C 6 )alkynyl, aryl, and heteroaryl, each being unsubstituted or substituted with 1, 2, 3, 4, or 5 independently-selected R 5 groups; each R 5 is independently selected from the group consisting of —OH, —Cl, Br, —I, —NH 2 , —CN, —O—(C 1 -C 6 ) alkyl, and phenyl; and X is selected from the group consisting of —Cl, —Br, —I, mesylate, and tosylate.