Sometimes the preposition "de" introduces a subordinate clause expressing a condition, the same way the conjunction "si" (if) does.
In this case "de" is followed by an infinitive.
Let's see some examples:
Notice how the infinitive construction admits different cases such as compound infinitives (de haber sabido...), the passive form (de ser aprobada...), the negative form (de no llegar...), modal verbs (de poder elegir...)
Pay special attention to pronouns in this type of construction as they can be attached to the end of the infinitive following the usual rule. For example, this sentence: