Patent ID: 7691367

Claim:
A branched polyalkylene glycol represented by formula (I): (R 1 -M n -X 1 ) 2 L(X 2 —X 3 —R 2 ) q (I) wherein L represents a nonplanar cyclic group represented by formula (II) or (III): of which 3 to 5 hydrogen atoms are removed from the moiety represented by following formula (II-a) or (III-a) to form binding group(s), wherein u represents an integer of 1 to 10 and ua represents an integer of 0 to 8; R 11 , R 12 and R 13 independently represent a hydrogen atom, a hydroxyl group, substituted or unsubstituted lower alkyl, lower alkoxy, amino, carboxy, cyano or formyl; and W represents CH 2 ; M represents OCH 2 CH 2 , OCH 2 CH 2 CH 2 , OCH(CH 3 )CH 2 , (OCH 2 CH 2 ) r —(OCH 2 CH 2 CH 2 ) s in which r represents an integer of 1 to 100,000, and s represents an integer of 1 to 100,000, or (OCH 2 CH 2 ) ra —(OCH(CH 3 )CH 2 ) sa in which ra and sa have the same meanings as r and s, respectively; n represents an integer of 10 to 100,000; q represents an integer of 1 to 3; R 1 represents a hydrogen atom, lower alkyl or lower alkanoyl; R 2 represents a hydroxyl group, carboxy, formyl, amino, vinylsulfonyl, mercapto, cyano, carbamoyl, halogenated carbonyl, halogenated lower alkyl, isocyanato, isothiocyanato, oxiranyl, lower alkanoyloxy, maleimido, succinimidooxycarbonyl, substituted or unsubstituted aryloxycarbonyl, benzotriazolyloxycarbonyl, phthalimidooxycarbonyl, imidazolylcarbonyl, substituted or unsubstituted lower alkoxycarbonyloxy, substituted or unsubstituted aryloxycarbonyloxy, tresyl, lower alkanoyloxycarbonyl, substituted or unsubstituted arolyloxycarbonyl, substituted or unsubstituted aryldisulfido or azido, X 1 represents a bond; O; S; alkylene; O(CH 2 ) ta in which ta represents an integer of 1 to 8; (CH 2 ) tb O in which tb has the same meaning as ta; NR 3 in which R 3 represents a hydrogen atom or lower alkyl; R 4 —NH—C(═O)—R 5 wherein R 4 represents a bond, alkylene or O(CH 2 ) tc in which tc has the same meaning as ta, and R 5 represents a bond, alkylene or OR 5a in which R 5a represents a bond or alkylene; R 6 —C(═O)—NH—R 7 wherein R 6 represents a bond, alkylene or R 6a O in which R 6a has the same meaning as the above R 5a , and R 7 represents a bond, alkylene or (CH 2 ) td O in which td has the same meaning as ta; R 8 —C(═O)—O in which R 8 has the same meaning as R 5a ; or O—C(═O)—R 9 in which R 9 has the same meaning as R 5a ; X 2 represents a bond, O or (CH 2 ) te O in which te has the same meaning as ta; X 3 represents a bond or alkylene; and 2 R 1 -M n -X 1 's and 1 to 3 X 2 —X 3 —R 2 's are independently the same or different.