Base-labile protecting groups for stepwise polymer synthesis

Compounds having the formula (I),

• wherein m, n and p are independently a positive integer;
• o is an integer larger than two;
• R1, R2, R3, R4, R5, R6 and R7 are independently a hydrogen, alkyl group or substituted alkyl group;
• X and Y are independently an oxygen or sulfur atom;
• LG is a leaving group;
• and bIPG is a base-labile protecting group defined
• by (II1), wherein R8, R9 and R10 are independently a hydrogen, alkyl group or substituted alkyl group, and EWG is an electron withdrawing group limited to
• alkenyl groups with less than eight carbons;
• alkynyl groups with three to eight carbons;
• phenyl group;
• furyl group;
• N-alkyl pyrrolyl group;
• substituted phenyl groups, furyl groups and N-alkyl pyrrolyl groups with substituent or substituents being halogen atom, nitro group, cyano group, alkyl group with less than eight carbons, alkoxyl group with its alkyl moiety having less than eight carbons, and dialkyl amino group with its alkyl moiety having less than eight carbons;
• bis(alkylthio) groups;
• and S,S′-(alkane-diyl) groups;
• by (II2), wherein R11, R12, R13, R14 and Rig are independently a hydrogen or alkyl group having less than five carbons;
• or
• by (II3), wherein R17, R18, R19 and R20 are independently a hydrogen or alkyl group having less than five carbons.

A process for stepwise polymer synthesis using one or more monomers containing a base-labile protecting group at one end and a leaving group at the other, wherein said process comprises at least a deprotection step under basic conditions to remove said base-labile protecting group and a coupling step using one of said monomers also under basic conditions to elongate the polymer, and said monomers are defined by (IV)

• wherein m and n are independently a positive integer;
• p is a positive integer if o is a positive integer or an integer larger than two if o is zero;
• R2, R3, R4, R5, R6 and R7 are independently a hydrogen, alkyl group or substituted alkyl group;
• X and Y are independently an oxygen or sulfur atom;
• LG is a leaving group;
• linker is one or more atoms that connect the two portions of the molecule together;
• and bIPG is said base-labile protecting group that is deprotectable using one or more bases in said deprotection step and is stable under the basic conditions in said coupling step, and is defined
• by (II1), wherein R8, R9 and R10 are independently a hydrogen, alkyl group or substituted alkyl group;
• and EWG (in some cases, R10 is part of the EWG) is an electron withdrawing group that enables the hydrogen in II1 acidic enough for deprotecting said bIPG in said deprotection step but not so acidic that said bIPG is unstable in said coupling step,
• by (II2), wherein R11, R12, R13, R14 and R15 are independently a hydrogen, alkyl group or substituted alkyl group,
• or
• by (II3), wherein R17, R18, R19 and R29 are independently a hydrogen, alkyl group or substituted alkyl group.