Proline-Catalyzed Asymmetric Synthesis of syn- and anti-1,3-Diamines

Chiral Ionic Liquids Based on l-Cysteine Derivatives for Asymmetric Aldol Reaction

Structure, and consequently properties, of ionic liquids can be easily tailored by changing cation/anion combinations and/or attaching functional groups. By grafting enantiopure moieties to the framework of ionic liquid it is possible to prepare bioinspired chiral molecules that can serve as a reaction medium, additive or even asymmetric catalyst. In this context, new chiral ionic liquids (CILs), based on biomolecules, such as aminoacids (l-Cysteine derivatives), have been synthesised and tested in asymmetric aldol condensation of aldehydes and ketones. The best results were obtained for CILs composed of S-methyl-l-cysteine cation and bis(trifluoromethane)sulfonimide anion, in the reaction of 2- or 4-nitrobenzaldehyde with acetone or cyclohexanone, giving the aldol product in moderate yields 70–76% and high ee values (up to 96%).

Electrophilic Aminating Agents in Total Synthesis

Classical amination methods involve the reaction of a nitrogen nucleophile with an electrophilic carbon center; however, in recent years, umpoled strategies have gained traction where the nitrogen source acts as an electrophile. A wide range of electrophilic aminating agents are now available, and these underpin a range of powerful C−N bond‐forming processes. In this Review, we highlight the strategic use of electrophilic aminating agents in total synthesis.

Synthesis of enantioenriched α-heteroatom functionalised aldehydes by chiral organocatalysis and their synthetic applications

Asymmetric organocatalysis is a versatile method for the enantioselective α-functionalisation of aldehydes. The synthetic scope for chiral α-heteroatom substituted aldehydes is examined including their applications in synthesis.

Dinuclear PhosphoiminoBINOL-Pd Container for Malononitrile: Catalytic Asymmetric Double Mannich Reaction for Chiral 1,3-Diamine Synthesis

A phosphoiminoBINOL ligand was designed to form a dinuclear metal complex that could hold a malononitrile molecule. The dinuclear bis(phosphoimino)binaphthoxy-Pd₂(OAc)₂ complex catalyzed a double Mannich reaction of N-Boc-imines with malononitrile to give chiral 1,3-diamines with high enantioselectivity. The rational asymmetric catalyst, which smoothly introduces the first coupling product to the second coupling reaction while avoiding the reverse reaction, facilitates the over-reaction into a productive reaction process.

Chemoselective room temperature E1cB N–N cleavage of oxazolidinone hydrazides from enantioselective aldehyde α-hydrazination: synthesis of (+)-1,4-dideoxyallonojirimycin

A room temperature method for hydrazide N–N cleavage is presented that completes enantioselective aldehyde α-hydrazination methodology.

Synthetic methods for 1,3-diamines

In this review, the synthetic methods for the preparation of 1,3-diamines and their applications in synthetic organic chemistry are summarized.

Total synthesis of (−)-(6R,11R,14S)-colletallol via proline catalyzed α-aminoxylation and Yamaguchi macrolactonization

A simple and efficient synthesis of 14-membered macrolide (−)-(6R,11R,14S)-colletallol was achieved in a highly diastereoselective manner using proline catalyzed alpha-aminoxylation and Yamaguchi protocol.

Divergent synthesis of various iminocyclitols from d-ribose

A very efficient route to the diastereoselective synthesis of polyhydroxy pyrrolidines, piperidines and azepanes from an aldehyde derivative of ribose is reported.

A stereocontrolled synthesis of Hagen's gland lactones via iterative proline catalyzed α-aminoxylation and oxa-Michael addition reactions

A simple and efficient synthesis of Hagen's gland lactones was achieved using a sequential α-aminoxylation/oxa-Michael approach in a highly diastereoselective manner with assignment of relative configurations.

Double-addition reaction of aryl methyl sulfones with N-tert-butylsulfinyl imines: diastereoselective and concise synthesis of 2-sulfonylated 1,3-diamines

We report a double-addition reaction of methyl phenyl sulfone and methyl 2-pyridyl sulfone with N-tert-butylsulfinyl imines. This method provides concise access to 2-sulfonylated 1,3-anti diamines with good to excellent diastereoselectivities. This protocol has the benefit of using readily accessible starting materials and is operationally simple.

A stereoselective approach to indolizidine and pyrrolizidine alkaloids: total synthesis of (−)-lentiginosine, (−)-epi-lentiginosine and (−)-dihydroxypyrrolizidine

The total synthesis of (−)-lentiginosine, epi-1,2-lentiginosine and dihydroxypyrrolizidine is reported from an aldehyde as a starting material using organocatalysis and asymmetric dihydroxylation as key steps.