Patent ID: 7241892

Claim:
A method for preparing a compound of formula (XVIIc): where: R 1 is selected from the group consisting of an aminomethylene, a protected aminomethylene, a derivatised aminomethylene group, a hydroxymethylene, a protected hydroxymethylene or a derivatised hydroxymethylene group; and R 4 is —H; or R 1 and R 4 together form a group of formula selected from the group consisting of formula (IV), (V) (VI) and (VII): R 5 is selected from the group consisting of —H, —OH, a protected —OH, and or derivatised —OH; R 7 is —OCH 3 and R 8 is —OH or R 7 and R 8 together form a group —O—CH 2 —O—; R 12 is selected from the group consisting of —H, —CH 3 and —CH 2 CH 3 ; R 14a and R 14b are both —H or one is —H and the other is selected from the group consisting of —OH, —OCH 3 and —OCH 2 CH 3 , or R 14a and R 4b together form a keto group; R 15 is selected from the group consisting of —H, —OH, a protected —OH, and a derivatised —OH; R 18 is selected from the group consisting of —H, —OH, a protected —OH, and a derivatised —OH; R 21 is selected from the group consisting of —H, —OH and —CN; and derivatives including compounds where the —NH 2 group in the compound of formula (VI) is derivatised; from a 21-cyano compound of formula (XVIb): where: R 1 is selected from the group consisting of an amidomethylene group or an acyloxymethylene group; R 5 and R 8 are independently selected from the group consisting of —H, —OH and —OCOCH 2 OH, or R 5 and R 8 are both keto and the ring A is a p-benzoquinone ring; R 12 is selected from the group consisting of —H, —CH 3 and —CH 2 CH 3 ; R 14a and R 14b are both —H or one is —H and the other is selected from the group consisting of —OH, —OCH 3 and —OCH 2 CH 3 , or R 14a and R 14b together form a keto group; and R 15 and R 18 are independently selected from the group consisting of —H or —OH, or R 15 and R 18 are both keto and the ring E is a p-benzoquinone ring; provided that at least one of the rings A or E is a p-benzoquinone ring; the reactions of the method comprising as needed: a) converting a quinone system for said ring E into the phenol system b) converting a quinone system for said ring A into the phenol system; c) converting the phenol system for said ring A into a methylenedioxyphenol ring; d) forming a bridged spiro ring system of formula selected from the group consisting of formula (IV), (V), (VI) and (VII) across the 1-position and 4-position in ring B; and e) acylation; (f) converting a compound where R 12 is —CH 3 to a group where R 12 is selected from —H and —CH 2 CH 3 ; and (g) converting a 21-cyano substituent to a substituent —OH.