A small library of C1-symmetric chiral diamines (L1−L9) was constructed via condensing exo-(−)-bornylamine or (+)-(1S,2S,5R)-menthylamine with various Cbz-protected amino acids. Among them, ligand L1/CuCl2·2H2O complex (2.5 mol %) shows outstanding catalytic efficiency for Henry reaction between a variety aldehydes and nitroalkanes to afford the expected products in high yields (up 98%) excellent enantioselectivities 99%) moderate good diastereoselectivities 90:10). This process is air-...

A Cu(I) photoredox-enabled reaction that selectively incorporates a difluoroalkyl group into N-aryl glycine derivatives has been established. Using bench-stable [Ph3PCF2H]+Br- salt, the -CF2H could be installed either directly on α-carbon of backbone or in three-component fashion using an alkene as bridge. series have evaluated, providing access to diverse unnatural amino esters and dipeptides with -CHF2 unit. The studies compatibility other perfluorinated alkyl radical precursors showed...

Four-component, quadruple cascade, one catalyst: An asymmetric four-component (ABC2) cascade reaction initiated by oxa-Michael addition of aliphatic alcohols to acrolein is reported (see scheme) provide high yields trisubstituted highly functionalized cyclohexene carbaldehydes with excellent diastereomeric and complete enantiomeric control. This process can be explained an iminium (Im)–enamine (En)–iminium (En) sequence mechanism.

Asymmetric tandem Michael addition−hemiacetalization between aliphatic aldehydes and (E)-2-(2-nitrovinyl)phenols was investigated for constructing benzopyran backbones. Interestingly, the diastereo- enantioselectivities changed markedly when reaction mediated by different types of secondary amine catalysts. The diphenylprolinol silyl ether 7 promoted with excellent (up to 99% ee) but moderate diastereoselectivities (2.8:1 10:1). Prolylprolinols are another type efficient catalyst. Among...

A metal-free and redox-neutral trifluoromethyl-hydrazination method of alkenes is described. With a commercially available photocatalyst low-cost reagents, both conjugated isolated could be converted to β-trifluoromethyl hydrazines in good excellent yields. The versatile hydrazine group can either used for heterocycle synthesis or cleaved afford corresponding amine. Mechanistic studies suggested this reaction goes through radical addition cascade pathway, featuring fast irreversible...

An iron-catalyzed C(sp3)–H cyanoalkylation of glycine derivatives with cyclobutanone oxime esters was established for the incorporation a cyano group into amino acids and peptides. In this reaction, Fe(NTf2)2 pyridine-oxazoline ligands form highly active catalysts that could simultaneously selectively activate both substrates. Preliminary mechanistic studies revealed excellent chemo-selectivity may stem from an in situ formed imine intermediate consecutive radical addition. The evidence...

A base-promoted domino reaction of 2-acyl-1-chlorocyclopropaneformic esters with amines is described. In the presence inorganic bases like Cs2CO3 or Mg(OEt)2, proceeded smoothly in acetonitrile to afford 2-pyrone derivatives modest excellent yields (up 97%). This provides a straightforward and transition metal-free protocol efficiently construct skeleton. possible mechanistic process involving 1,2-elimination hydrogen chloride, aza-Michael addition, ring-opening, intramolecular lactonization...

A visible-light-enabled catalytic formylation of fluoroalkyl imines is developed. With readily accessible starting materials and organocatalysts, this method provides a general approach to masked amino aldehydes. synergistic effect between the photosensitizer H atom transfer agent was proven pivotal transformation. After removing mask, free aldehydes can be obtained further converted various β-fluoroalkyl β-amino alcohols, which are attractive building blocks in synthesis bioactive...

Abstract A metal‐free and oxidant‐free method for the one‐pot preparation of quinazolin‐4( 3H )‐ones enabled by electrochemical oxidation is described. Together with 2‐aminobenzamides, a variety aldehydes were successfully applied to an acid‐catalyzed annulation direct anodic cascade, affording structurally diverse quinazoline‐4( in good excellent yields. Additionally, certain alcohols can be directly instead corresponding achieve same final products assistance electrolysis mediator (TEMPO)....

Abstract Several novel prolylprolinol catalysts have been designed and synthesized. This type of compound showed high catalytic efficiency on promoting the direct addition unmodified aldehydes to nitroalkenes. Among surveyed, least bulky member ( 8d ) exhibited best performance both stereoselectivity, providing products with up 97% ee value 1.5–5 mol% catalyst loading. Additionally, computational studies transition state conducted explain diastereo‐ enantioselectivity.

By combining the copper(II)-catalyzed asymmetric Henry reaction of o-alkynylbenzaldehydes with subsequent gold(I)-catalyzed cycloisomerization, optically active 1H-isochromenes and 1,3-dihydroisobenzofurans were successfully synthesized in good overall yields to excellent enantioselectivities (up 98%). Various substrates investigated, a correlation between regioselectivity electronic nature was studied. The electro-donating groups at alkynyl moiety preferred 6-endo-dig manner generated 3 as...

Abstract A two‐step sequence to ethyl α‐fluorocyclopropanecarboxylates has been developed. Ethyl α‐chlorocyclopropanecarboxylates were first obtained through a Michael‐initiated ring closure reaction of terminal electron‐deficient olefins with 2,2‐dichloroacetate under mild basic conditions. Subsequent smooth conversion into the corresponding monofluorinated analogues in good yields was halogen exchange potassium bifluoride. Further investigation clearly demonstrated that bifluoride this...

We herein describe a novel TEMPO oxoammonium salt initiated Pictet–Spengler reaction of imines, generated in situ from carbonyl compounds and pyrrole- or indole-containing substrates, to afford 4,5-dihydropyrrolo[1,2-a]quinoxalines 5,6-dihydroindolo[1,2-a]quin­oxalines good excellent yields. Moreover, one-pot synthesis biologically important quinoxaline is achieved via cyclization–dehydrogenation process using one equivalent the salt.

Selective delivery of an N-nucleophile onto alkyl radical is a challenging step in redox catalysis. In this work, di-tert-butyl hydrazodiformate was found to be unique effective amination reagent Cu-catalyzed C(sp3)–N bond formation reactions that involve intermediates. This method applicable both electron-deficient and electron-rich radicals, we were thus able achieve the direct C–N coupling activated bromides, as well carboamination general alkenes based on chemistry. Mechanistic studies...

Abstract A series of stable chiral C 1 ‐symmetric dinitrogen ligands were conveniently synthesized in high yields by condensation amines [(–)‐ exo ‐bornylamine or (+)‐(1 S ,2 ,5 R )‐menthylamine] with various substituted imidazolecarbaldehydes. With the assistance base, ligand L1 combination CuCl 2 · 2H O (2.5 mol‐% 5.0 mol‐%) can efficiently promote nitroaldol (Henry) reactions between a variety aldehydes and nitromethane. Both aromatic aliphatic tolerated our catalytic system, affording...

A new, rapid and high-yielding method to prepare 3,4-disubstituted 2-trifluoromethylquinolines by a palladium catalyzed tandem Sonogashira–alkyne carbocyclization of β-trifluoromethyl β-enaminoketones with arynes is described. Moderate excellent yields have been achieved under mild conditions. This reaction can also be expanded the non-fluorine containing substrates. The mechanism discussed.

A new Rh-catalyzed intramolecular coupling reaction of a CF2Br group with 2-aryl indole or pyrrolevia C–H bond activation is presented. This represents way incorporating difluoromethylene groups into organic compounds. Preliminary mechanistic studies suggest that this might not occur via conventional free radical pathway.