Catalytic enantioselective synthesis of 2-pyrazolines one-pot condensation/6π-electrocyclization: 3,5-bis(pentafluorosulfanyl)-phenylthioureas as powerful hydrogen bond donors.

A new conjugate-base-stabilized carboxylic acid (CBSCA) containing a 3,5-bis(pentafluorosulfanyl)phenylthiourea functionality catalyses challenging one-pot condensations/6π-electrocyclizations of hydrazines and α,β-unsaturated ketones under mild conditions. Structurally diverse -aryl 2-pyrazolines are obtained in good yields and enantioselectivities. The superior performance of 3,5-bis(SF)phenylthioureas over the widely used 3,5-bis(CF)phenylthioureas is further demonstrated in the Michael addition of dimethyl malonate to nitrostyrene, using a new Takemoto-type catalyst.

Synthesis of Polycyclic Imidazoles via α-C-H/N-H Annulation of Alicyclic Amines.

Secondary alicyclic amines are converted to their corresponding ring-fused imidazoles in a simple procedure consisting of oxidative imine formation followed by a van Leusen reaction. Amines with an existing α-substituent undergo regioselective ring-fusion at the α'-position. This method was utilized in a synthesis of fadrozole.

Alicyclic-Amine-Derived Imine-BF Complexes: Easy-to-Make Building Blocks for the Synthesis of Valuable α-Functionalized Azacycles.

A new strategy to access α-functionalized alicyclic amines via their corresponding imine-BF complexes is reported. Isolable imine-BF complexes, readily prepared via dehydrohalogenation of N-bromoamines in a base-promoted/18-crown-6 catalyzed process followed by addition of boron trifluoride etherate, undergo reactions with a wide range of organometallic nucleophiles to afford α-functionalized azacycles. Organozinc and organomagnesium nucleophiles add at ambient temperatures, obviating the need for cryogenic conditions.

C-H Bond Functionalization of Amines: A Graphical Overview of Diverse Methods.

This Graphical Review provides a concise overview of the manifold and mechanistically diverse methods that enable the functionalization of sp C-H bonds in amines and their derivatives.

α,α'-C-H Bond Difunctionalization of Unprotected Alicyclic Amines.

A simple one-pot procedure enables the sequential, regioselective, and diastereoselective introduction of the same or two different substituents to the α- and α'-positions of unprotected azacycles. Aryl, alkyl, and alkenyl substituents are introduced via their corresponding organolithium compounds. The scope of this transformation includes pyrrolidines, piperidines, azepanes, and piperazines.