“…Immense synthetic and pharmacological utilities of such piperidines have inspired researchers to develop new strategies for their syntheses. Toward this end, several efforts have been devoted − mostly from substituted pyridines, amino alcohols, − imines, − aldol reaction, reductive amination reactions, − ring expansion and heterocyclic rearrangements, − aza-conjugate additions, various metal- and acid-catalyzed cyclizations, Mannich-type reactions, olefin metathesis, and hetero-Diels−Alder reactions, etc. It is still challenging for organic chemists to develop more efficient synthetic routes toward functionalized piperidines with structural diversity and high diastereo- as well as enantioselectivity.…”