Patent ID: 6974868

Claim:
A compound of formula (II): where R 1 is C 3-5 alkyl optionally substituted by 1 or more halogen atoms; R 3 and R 4 are both hydroxy; R is XOH, where X is OCH 2 CH 2 , or a protected derivative thereof, or R 3 and R 4 together form a bond in the 5-membered ring, or R is CH 2 CH 2 OR′ where R′ is C 1-6 alkyl or benzyl, and L is halogen or SR, or said hydroxy groups R 3 and R 4 are protected as groups OP 1 and OP 2 where P 1 and P 2 are protecting groups selected from the group consisting of C 1-6 alkyl, benzyl, (C 1-6 alkyl) 3 Si and C(O)C 1-6 alkyl or said groups P 1 and P 2 , together with the atoms to which they are attached, may form an alkylidene ring or an alkoxymethylidene ring.