Low temperature synthesis of rapamycin derivatives

A method for obtaining a compound having the structure of Formula I

• the method comprising:
• a) combining in a reaction mixture an organic solvent, an organic base compound having a nitrogen heteroatom, a compound having the structure of Formula II
• and
• a compound having the structure of Formula III
• b) maintaining the reaction mixture at a temperature of from 25° C. to 55° C.;
• and
• c) separating from the reaction mixture a compound having the structure of Formula I;
• wherein
• R1 is (CH2)e—O—(CH2)f—H;
• e is an integer selected from 1-5;
• f is an integer selected from 1-5;
• and
• R2 is hydrogen;
• thereby obtaining a compound having the structure of Formula I.