491-35-0

Usage

Uses

Used in Dye Preparation:
Lepidine is utilized in the preparation of certain dyes, contributing to its significance in the chemical industry.
Used in Pharmaceutical Synthesis:
In the pharmaceutical industry, Lepidine serves as a reagent in the synthesis of azetidine-based ene-amides. These compounds are potent bacterial enoyl ACP reductase inhibitors, which are essential in the development of new antibiotics to combat drug-resistant bacterial infections.
Used in Fluorescent DNA Imaging:
Lepidine is also used as a reagent in the synthesis of cyanine-styryl dyes with enhanced photostability. These dyes are crucial for fluorescent DNA imaging, allowing for better visualization and analysis of DNA structures in various research and diagnostic applications.

Synthesis Reference(s)

Tetrahedron Letters, 28, p. 5291, 1987 DOI: 10.1016/S0040-4039(00)96710-8

Purification Methods

Reflux lepidine with BaO, then fractionally distil it. Further purify it via its recrystallised dichromate salt (m 138o) (from H2O). [Cumper et al. J Chem Soc 1176 1962.] [Beilstein 20 III/IV 3477, 20/7 V 389.]

Upstream product

• 75-21-8 oxirane 
• 62-53-3 aniline 
• 91-22-5 quinoline 
• 67-56-1 methanol 
• 607-66-9 4-methylquinolin-2-ol 
• 634-47-9 2-chloro-4-methylquinoline 
• 607-65-8 2-iodo-4-methylquinoline 
• 28448-12-6 2-hydroxy-4-methyl-quinoline-3-carbonitrile 
• 6607-66-5 1,3,3-trimethoxybutane 
• 142-04-1 aniline hydrochloride 
• 64-17-5 ethanol 
• 6975-85-5 1-methoxybutan-3-one 
• 6220-79-7 4-phenylamino-butan-2-one 
• 75-07-0 acetaldehyde 

Downstream Products

• 5450-80-6 1-[4]quinolylmethyl-pyridinium; iodide 
• 18122-29-7 4-(β-Piperidinoethyl)-quinoline 
• 55908-35-5 2--ethanol-(1) 
• 486-74-8 4-quinolinic acid 
• 15941-82-9 (3-ethyl-benzothiazol-2-yl)-(1-ethyl-[4]quinolyl)-methinium ; iodide 
• 94319-01-4 1-isopentyl-4-methyl-quinolinium; iodide 
• 7543-20-6 1-Phenyl-2-(4-quinolyl)ethanone 
• 14003-46-4 2-(quinolin-4-yl)acetonitrile 
• 17025-32-0 4-(4t-[4]quinolyl-buta-1,3-dien-t-yl)-N,N-dimethyl-aniline 
• 2039-83-0 3,4-dichlorostyrene 
• 102947-82-0 N-ethyl-N-benzyl-4-(trans-2-[4]quinolyl-vinyl)-aniline 
• 40317-65-5 (E)-4-(4-dimethylaminostyryl)quinoline 
• 32863-57-3 1-benzyl-4-methyl-quinolinium; iodide 
• 40317-03-1 4-[(E)-2-(4-chlorophenyl)ethenyl]quinoline 

Relevant academic research and scientific papers

A novel approach to vapor-phase synthesis of 2- and 4-methylquinoline from lactic acid and aniline

A novel and green route for vapor-phase synthesis of 2- and 4-methylquinoline was provided in this work, in which lactic acid as one of the reactants was for the first time employed. Various influencing factors, including types of catalysts, reaction temperature and stability of catalyst were investigated systematically. The results showed that a 67.6% total yield of quinolines was obtained over the HBeta catalyst. The characterization by using BET, NH3-TPD and pyridine-IR techniques revealed that strong Br?nsted acid sites are favorable for generation of 2- and 4-methylquinoline whereas Lewis acid sites could increase the proportion of 4-methylquinoline in target products. Besides, a feasible reaction pathway to synthesize 2- and 4-methylquinoline was proposed on the basis of the reaction products.

Reactivity of quinoline- and isoquinoline-based heteroaromatic substrates in palladium(0)-catalyzed benzylic nucleophilic substitution

(Formula presented) Quinolylmethyl, 1-(isoquinolyl)ethyl, and 1-(quinolyl)ethyl acetates reacted with dimethylmalonate anion in the presence of a Pd(0) catalyst to give products of nucleophilic substitution and/or byproducts, depending upon the substitution pattern. The observed side reactions were reduction in the case of primary acetates and elimination or elimination/Michael-type addition sequence for secondary substrates.

Vapour-phase synthesis of 2-methyl- and 4-methylquinoline over BEA* zeolites

4-Methylquinoline and 2-methylquinoline were synthesized from acetaldehyde and aniline in the gas phase over BEA* zeolite catalysts. High combined yields of 2- and 4-methyl-substituted quinolines were obtained with H-BEA* zeolite and with BEA*-F synthesized in fluoride medium, with 4-methylquinoline being the predominant isomer. Postsynthesis fluorination of the H-BEA* with ammonium fluoride leads to dealumination and formation of extra-framework aluminium fluoride compounds. Product selectivities changed with time over this catalyst, such that 2-methylquinoline became the predominant product. New insight into the reaction mechanism is offered, and previous propositions can be rationalized based on these new results.

Highly Chemoselective Deoxygenation of N-Heterocyclic N-Oxides Using Hantzsch Esters as Mild Reducing Agents

Herein, we disclose a highly chemoselective room-temperature deoxygenation method applicable to various functionalized N-heterocyclic N-oxides via visible light-mediated metallaphotoredox catalysis using Hantzsch esters as the sole stoichiometric reductant. Despite the feasibility of catalyst-free conditions, most of these deoxygenations can be completed within a few minutes using only a tiny amount of a catalyst. This technology also allows for multigram-scale reactions even with an extremely low catalyst loading of 0.01 mol %. The scope of this scalable and operationally convenient protocol encompasses a wide range of functional groups, such as amides, carbamates, esters, ketones, nitrile groups, nitro groups, and halogens, which provide access to the corresponding deoxygenated N-heterocycles in good to excellent yields (an average of an 86.8% yield for a total of 45 examples).

Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies

We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.

Synthesis of Quinolines via the Metal-free Visible-Light-Mediated Radical Azidation of Cyclopropenes

We report the synthesis of quinolines using cyclopropenes and an azidobenziodazolone (ABZ) hypervalent iodine reagent as an azide radical source under visible-light irradiation. Multisubstituted quinoline products were obtained in 34-81% yield. The reaction was most efficient for 3-trifluoromethylcyclopropenes, affording valuable 4-trifluoromethylquinolines. The transformation probably proceeds through the cyclization of an iminyl radical formed by the addition of the azide radical on the cyclopropene double bond, followed by ring-opening and fragmentation.

Copper-mediated formal [5+1] annulation of 2-vinylanilines and glyoxylic acid: A facile approach for the synthesis of 4-arylated quinolines

A copper-mediated formal [5 + 1] oxidative annulation of 2-vinylanilines and glyoxylic acid to 4-arylated quinolines was developed. A series of 4-arylated quinoline derivatives were obtained in good to excellent yields. This protocol could be carried out efficiently on gram scale. The transformation probably underwent nucleophilic addition/6π electrocyclization/oxidative aromatization and the elimination of CO2 cascade processes.

Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen

The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.

Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles

N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.

Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles

Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.