95545-95-2

Upstream product

• 1300751-08-9 N-cinnamylidene-α-tetralone hydrazone 
• 28353-74-4 3,4-dihydronaphthalen-1(2H)-one O-acetyl oxime 
• 104-55-2 3-phenyl-propenal 
• 6261-32-1 2-benzylidene-1-tetralone 
• 28353-74-4 (E)-3,4-dihydronaphthalen-1(2H)-one O-acetyl oxime 
• 95546-02-4 Ethoxy-2 phenyl-4 tetrahydro-3,4,5,6 2H-naphtol<1,2-b>pyranne 

Relevant academic research and scientific papers

4-HO-TEMPO-Catalyzed Redox Annulation of Cyclopropanols with Oxime Acetates toward Pyridine Derivatives

A 4-HO-TEMPO-catalyzed redox strategy for the synthesis of pyridines through the annulation of cyclopropanols and oxime acetates has been developed. This protocol features good functional group tolerance and high chemoselectivity and also promises to be efficient for the late-stage functionalization of skeletons of drugs and natural products. Mechanism studies indicate that the reaction involves the in situ generated α,β-unsaturated ketones and imines as the key intermediates, which are derived from cyclopropanols and oxime acetates via a TEMPO/TEMPOH redox cycle, respectively. The pyridine products are formed as a result of annulation of enones with imines followed by TEMPO-catalyzed oxidative aromatization by excess oxime acetates. This method not only realizes the TEMPO-catalyzed redox reaction but also broadens the frontiers for TEMPO in catalysis.

Metal-Free Assembly of Polysubstituted Pyridines from Oximes and Acroleins

Transition-metal-catalyzed synthesis of N-heterocycles from oximes has been previously well established. In this paper, for the first time a metal-free protocol with the combinational employment of iodine and triethylamine has been demonstrated to be effective to trigger the oxime-based synthesis of pyridines with high chemo-selectivity and wide functional group tolerance. A broad range of functional pyridines were prepared in moderate to excellent yields. While neither iodine nor triethylamine could trigger this transformation, mechanistic experiments indicated a radical pathway for the reaction. The resultant 2-aryl-substituted pyridines have been proved to be versatile building blocks in a range of transition-metal-catalyzed C-H functionalization reactions. (Chemical Equation Presented).

Route to Highly Substituted Pyridines

Pyridine rings are common structural motifs found in a number of biologically active compounds, including some top-selling pharmaceuticals. We have developed a new approach to access substituted pyridines. The method aims to provide a reliable synthesis of a diverse range of substituted pyridines through a three-step procedure. Readily available enones are first converted into 1,5-dicarbonyls through a two-step Hosomi-Sakurai allylation/oxidative cleavage sequence, which is followed by subsequent cyclization to the corresponding pyridine using hydroxylamine hydrochloride. A variety of substituted pyridines have been synthesized using this method.

Modular pyridine synthesis from oximes and enals through synergistic copper/iminium catalysis

We describe here a [3+3]-type condensation reaction of O-acetyl ketoximes and α,β-unsaturated aldehydes that is synergistically catalyzed by a copper(I) salt and a secondary ammonium salt (or amine). This redox-neutral reaction allows modular synthesis of a variety of substituted pyridines under mild conditions with tolerance of a broad range of functional groups. The reaction is driven by a merger of iminium catalysis and redox activity of the copper catalyst, which would initially reduce the oxime N-O bond to generate a nucleophilic copper(II) enamide and later oxidize a dihydropyridine intermediate to the pyridine product.

Cyclization reactions of 3,4-diazaheptatrienyl metal compounds. Pyridines from an anionic analogue of the Fischer indole synthesis: Experiment and theory

Unsymmetrical N,N′-bisalkylidene hydrazines 7a,b, 10a-c and 13, which are accessible in good to excellent yields from hydrazones 6, 9, and 12 and commercially available α,β-unsaturated carbonyl compounds, are converted into 3,4-diazaheptatrienyl anions 14