ABSTRACT
A highly enantioselective Mannich reaction of α-fluoroindanones with isatin-derived N-Boc-ketimines catalyzed by a quinine-derived phase-transfer catalyst was developed. A variety of 3-substituted 3-amino-2-oxindoles bearing fluorine-containing, vicinal, tetrasubstituted stereocenters were constructed using this protocol in high yields (83-95%), with moderate to excellent enantioselectivities (66-91%) and high diastereoselectivities (up to >99:1).
ABSTRACT
A facile and green approach for the preparation of PEGn-NH2s from PEGn-N3s in water with DTT as the reduction reagent has been developed, avoiding the introduction of metal ions and difficulties in purification compared to the traditional synthesis process of PEGn-NH2s. A series of high-purity linear and multiarm PEGn-NH2s with different molecular weights were synthesized, demonstrating the versatility of this method. Additionally, HS-PEG45-NH2 with high fidelity of thiol and amine was easily prepared through the one-step two functional group conversion of N3-PEG45-S-S-PEG45-N3, and the PEG-based NH2-PEG@AuNPs were also prepared. This technology will promote the application of PEGn-NH2s in the fields of medicine and biomaterials.
Subject(s)
Metal Nanoparticles , Polyethylene Glycols , Azides , Dithiothreitol , Amines , GoldABSTRACT
An anodically oxidizing trifluoromethylation cascade of N-cyanamide alkene bearing two electronically differentiated olefin moieties was reported, in which various N-unsaturated acyl cyanamide alkenes and CF3SO2Na acting as readily available starting materials furnished nonaromatic fused azaheterobicyclic compounds in a highly efficient and sustainable manner. The broad substrate scope, facile scalability, and sustainability enabled this electrochemical process to be an appealing complement for trifluoromethylated cyclic amidines.