Polyoxyalkylene-modified lipid and method for producing the same

A method for producing a polyoxyalkylene-modified lipid represented by the following formula (1), comprising Step (II) after Step (I):

• wherein, R1 and R2 are hydrocarbon groups which are the same as or different from each other and which contain 4 to 24 carbon atoms, R3 is a divalent hydrocarbon group containing 1 to 6 carbon atoms, OA is oxyalkylene groups containing 2 to 4 carbon atoms, n is the average addition mole number of the oxyalkylene groups and is 5 to 1,000, and Z is a group containing either maleimide or iodoacetamide;
• Step (I):
• a step of obtaining a compound represented by the following formula (3) by deprotecting P of a compound represented by the following formula (2) with a methanesulfonic acid:
• P—R3—(OA)n-Z (2)
• wherein, OA is oxyalkylene groups containing 2 to 4 carbon atoms, n is the average addition mole number of the oxyalkylene groups and is 5 to 1,000, R3 is a divalent hydrocarbon group containing 1 to 6 carbon atoms, Z is a group containing either maleimide or iodoacetamide, and P is a chemically protected amino group which is to be deprotected with acid;
• X—R3—(OA)n-Z (3)
• wherein, OA is oxyalkylene groups containing 2 to 4 carbon atoms, n is the average addition mole number of the oxyalkylene groups and is 5 to 1,000, R3 is a divalent hydrocarbon group containing 1 to 6 carbon atoms, Z is a group containing either maleimide or iodoacetamide, and X is an ion pair of an amino group and the methanesulfonic acid;
• Step (II):
• a step of obtaining the compound represented by Formula (1) in such a manner that a solution containing the compound represented by Formula (3) is added dropwise to a solution containing a compound represented by the following formula (4) to cause reaction:
• wherein, R1 and R2 are hydrocarbon groups which are the same as or different from each other and which contain 4 to 24 carbon atoms and Y is an activated carbonate group.