A Simple Stereoselective Route to α‐Trifluoromethyl Analogues of Piperidine Alkaloids

Abstract

The highly diastereoselective synthesis of five trifluoro-substituted analogues of mono-, di-, and trisubstituted piperidine alkaloids was accomplished in two to four steps from 2-trifluoromethyl keto-protected 4-piperidones, prepared by an intramolecular Mannich-type reaction methodology. A sim-

Mild and Neutral Deprotections Catalyzed by Cerium(IV) Ammonium Nitrate

“…Furthermore, the procedure tolerates the presence of a terminal alkene, a ketone, or an enone in the same molecule (Table 2, entries 3-5), as well as benzyl ethers or protected amide functionalities (Table 2, entries 7, 9, and 10). 10 Moreover, ketals and acetals derived from acyclic carbonyl compounds are also unraveled smoothly.…”

Synthesis of Substituted α-Trifluoromethyl Piperidinic Derivatives

“…A cyclization is taking place to produce the 2-trifluoromethylpiperidinic derivatives 86 . The diastereoselectivity can be explained by the six-membered ring chair transition states XIV , in which the steric interactions are minimized (Scheme 27) [55,56,57]. …”

Domino Imino-Aldol−Aza-Michael Reaction: One-Pot Diastereo- and Enantioselective Synthesis of Piperidines

“…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.…”