Three-Component Couplings among Heteroarenes, Difluorocyclopropenes, and Water via C–H Activation

Abstract

Three-component couplings have been realized for efficiently constructing various nitrogen-containing skeletons via C–H activation, where difluorocyclopropenes have been first identified as coupling partners. Many substrates including sp2 and sp3 C–H substrates were well tolerated, furnishing the corresponding products in good yields. Furthermore, a catalyst-dependent reaction was also developed, enabling divergent construction of two different frameworks. The application value of these reactions was demonstrated in gram-scale experiments with as little as 1 mol % catalyst.

One Dianionic Luminophore with Three Coordination Modes Binding Four Different Metals: Toward Unexpectedly Phosphorescent Transition Metal Complexes

“…The reactions were carried out by adapting and optimizing methodologies from earlier studies on comparable syntheses. [ 35 , 96 , 97 ] First, 3‐(methoxycarbonyl)phenylboronic acid was reacted with 2‐bromopyridine in a Suzuki‐Miyaura cross‐coupling reaction to obtain methyl 3‐(pyridin‐2‐yl)benzoate ( 1 ) in good yields (80%). In a second step, 1 was reacted with a tenfold excess of hydrazine hydrate in order to obtain the corresponding 3‐(pyridin‐2‐yl)benzohydrazide ( 2 ) in quantitative amounts (100%).…”

Unique Pseudo-Cross-Conjugated Mesomeric Betaines via an Iodate-Promoted Reaction of 3,3-Difluorocyclopropenes, Pyridines, and Anilines

“…Additionally, oxygen heteroatoms in 38 had a positive impact on its ionization by APCI and, therefore, improved traceability in LC–MS. It is reasonable to consider difluorocyclopropene 38 as a synthetic equivalent of cyclopropenone 39 which, in turn, is a straight precursor of C3-free indolizin-1-ols.…”

Novel Two-Step Synthesis of N-Alkylated 2,3-Diaryl-4-quinolones

“…The second option to access 2,3-diaryl-4-quinolones 5 or 6 would be a set of dozen or so formally one-step syntheses 39 40 41 42 43 44 45 46 47 48 49 50 51 that take advantages of suitable precursors (Scheme 3 ). The main hurdle here, however, is often the limited availability of the latter, which somewhat constrains the practical applications of these methods.…”

“…36,37 Nevertheless, the free NH 2,3-diaryl-4-quinolones 6 could be obtained from the corresponding 2-aryl derivatives 4 as well either by a metal-free arylation using arylhydrazines as aryl radicals source 38 (Scheme 2d) or through a protection-deprotection detour route. 22,31 The second option to access 2,3-diaryl-4-quinolones 5 or 6 would be a set of dozen or so formally one-step syntheses [39][40][41][42][43][44][45][46][47][48][49][50][51] that take advantages of suitable precursors (Scheme 3). The main hurdle here, however, is often the limited availability of the latter, which somewhat constrains the practical applications of these methods.…”