There is provided a process for the preparation of a compound of formula (7): formula (7) wherein R 1 represents an alkyl group, R 2 represents an aryl group, R 3 represents hydrogen, a protecting group or an alkyl group； and R 4 represents hydrogen, a protecting group or a SO 2 R 5 group where R 6 is an alkyl group, which comprises a) hydroxylating a compound of formula (1): formula (1) wherein Y represents a halo group, P 1 represents hydrogen or a protecting group, and W represents =O or -OP 2 , in which P 2 represents hydrogen or a protecting group, to give a compound of formula (2): formula (2) b) oxidising the compound of formula (2) to give a compound of formula (3): formula (3) c) coupling the compound of formula (3) with a compound of formula (4): formula (4) wherein R 3 represents a protecting group or an alkyl group, R 4 represents a protecting group or a SO 2 R 5 group where R 5 is an alkyl group； and R 6 represents (PR 7 R 8 )+X - or P (=O)R 7 R 8 in which X is an anion and R 7 and R 8 each independently is an alkyl, aryl, alkoxy or aryloxy group, to give a compound of formula (5): formula (5) wherein R 3 represents a protecting group or an alkyl group； and R4 represents a protecting group or a SO 2 R 5 group where R 5 is an alkyl group, d) when W represents -OP 2 , removing any P 2 protecting group and oxidising the compound of formula (5) to give a compound of formula (6): formula (6) and e) subjecting the compound of formula (5) when W represents =O, or compound of formula (6) to ring-opening, removal of any P 1 protecting groups, and optionally removing any additional protecting groups to give a compound of formula (7).
