Convergent processes for the synthesis of a GARFT inhibitor containing a methyl substituted thiophene core and intermediates therefor

The invention relates to processes for the preparation of a GARFT inhibitor containing a methyl substituted thiophene core having the following structure: wherein each of R1 and R2 are independently a hydrogen atom or a moiety that together with the attached CO2 forms a readily hydrolyzable ester group; from an intermediate of the formula, , wherein R3 is a moiety that together with the attached CO2 forms a readily hydrolyzable ester group; Pg1 is an amino protecting group; R4 is H; or Pg1 can optionally be taken together with R4 and the nitrogen to which Pg1 and R4 are attached to form (i) an imine; or (ii) a fused or bridged bicyclic ring or a spirocyclic ring, wherein said ring is saturated and contains from 5 to 12 carbon atoms in which up to 2 carbon atoms are optionally replaced with a hetero moiety selected from O, S(O)j wherein j is an integer from 0 to 2, and -NR8-, provided that two O atoms, two S(O)j moieties, or an O atom and a S(O)j moiety are not attached directly to each other; R5 is selected f