Lin He

NHCs Catalyzed Hydrophosphonylation ofα-Ketoesters andα-Trifluoromethyl Ketones

N-Heterocyclic carbenes catalyzed hydrophosphonylation reaction of α-ketoesters and α-trifluoromethyl ketones was developed. Under the catalysis of 10 mol% IPr, α-ketoesters or α-trifluoromethyl ketones reacted with dialkyl phosphites to provide quaternary α-hydroxyphosphonates in good to excellent yield.

N-Heterocyclic carbene-catalyzed formal cross-coupling reaction of α-haloenals with thiols: organocatalytic construction of sp2 carbon–sulfur bonds

A novel N-heterocyclic carbene (NHC)-catalyzed formal cross-coupling reaction between α-haloenals and thiols was developed. In the presence of 5 mol% NHC precursors and 1.6 equiv. potassium carbonate, various thiols coupled with α-haloenals to produce α-thioenals in 53% to 91% yield and excellent Z-selectivity.

Diastereoselective synthesis of N-aryl tetrahydroquinolines and N-aryl indolines by the tandem reaction of arynes.

A tandem reaction of arynes with α- or β-amino ketones has been revealed. Arynes react with β-amino ketones through a cascade insertion-cyclization process to afford N-aryl tetrahydroquinolines in good yield with excellent anti-selectivity. Meanwhile, the coupling of arynes with α-amino ketones produces multisubstituted indolines in high yield with syn-selectivity. A quaternary carbon center can be constructed in this process, and the reaction can be easily scaled up.

Organocatalytic direct difluoromethylation of aldehydes and ketones with TMSCF2H

An organic Lewis base promoted direct difluoromethylation reaction of carbonyl compounds with Me3SiCF2H has been studied. The Schwesingers superbase can efficiently activate the Si–CF2H bond and initiate the difluoromethylation of aldehydes and ketones under very mild conditions, producing difluoromethyl adducts in 42–99% yields.

N-Heterocyclic Carbene-Catalyzed Diastereoselective Vinylogous Michael Addition Reaction of γ-Substituted Deconjugated Butenolides.

An efficient N-heterocyclic carbene (NHC)-catalyzed vinylogous Michael addition of deconjugated butenolides was developed. In the presence of 5 mol % of the NHC catalyst, both γ-alkyl- and aryl-substituted deconjugated butenolides undergo vinylogous Michael addition with various α, β-unsaturated ketones, esters, or nitriles to afford γ,γ-disubstituted butenolides containing adjacent quaternary and tertiary carbon centers in good to excellent yields with excellent diastereoselectivities. In this process, the free carbene is assumed to act as a strong Brønsted base to promote the conjugate addition.

A simple and efficient synthesis of 9-arylfluorenes via metal-free reductive coupling of arylboronic acids and N-tosylhydrazones in situ

A general, yet efficient synthesis method of 9-arylfluorenes via metal-free reductive coupling of N-tosylhydrazones and arylboronic acids has been developed. This methodology is realized by a one-pot protocol in two steps involving the preparation of N-tosylhydrazones by reacting tosylhydrazide with 9-fluorenone derivatives, followed by the reductive coupling of arylboronic acid in the presence of potassium carbonate to afford various 9-arylfluorenes analogues in moderate to excellent yields. Importantly, the catalytic system presented here enables the use of easily accessible starting materials and can be employed on a wide variety of substrates with good functional group tolerance. This protocol could also be particularly useful for the synthesis of 9-fluorenyl-substituted carbazolyl compounds.

Aryne-induced dearomatized phosphonylation of electron-deficient azaarenes

An aryne-induced dearomatized phosphonylation reaction has been developed. Electron-deficient azaarenes such as quinolines, isoquinolines, phenanthroline and acridine undergo multicomponent reaction with arynes and dialkylphosphites to afford the corresponding dearomatized phosphonylated heterocycles in 50–90% yields.

N-heterocyclic carbene-catalysed pentafluorophenylation of aldehydes

N-heterocyclic carbenes have been utilized as highly efficient organocatalysts to catalyse multifluorophenylation of aldehydes with pentafluorophenyltrimethylsilane or bis(trimethylsilyl)tetrafluorobenzene to afford the corresponding fluorinated adducts in 49–99% yields.

Diastereoselective Synthesis of γ-Butenolides Catalyzed by Potassium tert-Butoxide

Abstract Potassium tert-butoxide (0.1 mol%) catalyzed a vinylogous Mukaiyama aldol reaction between aromatic and aliphatic aldehydes with 2-(trimethylsilyloxy)furan. The corresponding γ-butenolides were obtained in good yields with good diastereoselectivities. GRAPHICAL ABSTRACT

N-heterocyclic carbene-catalyzed regio- and stereoselective hydrothiolation reaction of alkynes

Abstract N-heterocyclic carbenes (NHCs) have been utilized as Brønsted base to catalyze the hydrothiolation reaction between alkynes and thiols to produce the vinyl sulfides stereoselectively. Graphical Abstract Graphical Abstract