Ct. of Appeals lacked jurisdiction to consider Dist. Ct.’s order remanding to state court, plaintiff’s state-court wrongful death action, after Dist. Ct. had granted plaintiff’s motion to add two non-diverse employees of defendant as defendants, which served to destroy diversity jurisdiction that formed basis of initial removal of case to federal court. Under section 1447(d), such remand orders are not reviewable, and Ct. of Appeals lacked jurisdiction to review order that added two new non-diverse defendants since said order was not final and appealable. Moreover, defendant was not entitled to mandamus relief, where propriety of order granting plaintiff’s motion to add non-diverse defendants could be reviewed in state court.