A process for preparing a crystalline rapamycin analog includes: combining
the rapamycin analog with an organic medium to form a mixture; incubating
the mixture until the rapamycin analog crystallizes; and recovering the
crystalline rapamycin analog. The organic medium can be a solvent, and
the process can include causing the rapamycin analog to dissolve into the
solvent, and incubating the solvent until the rapamycin analog
crystallizes. The following can also be performed: forming a slurry of
crystalline rapamycin analog; stirring the rapamycin analog mixture until
the rapamycin analog crystallizes; saturating the rapamycin analog
solution; forming a supersaturated rapamycin analog solution; combining
an antisolvent with the rapamycin analog and the solvent to form a
biphasic mixture, and incubating the biphasic mixture to cause a
liquid-liquid phase split.