One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

Figure 1: Microwave flow reactor for the Bohlmann–Rahtz synthesis of pyridine 2b.

 read at
http://www.beilstein-journals.org/bjoc/single/articleFullText.htm?publicId=1860-5397-9-232 

The Bohlmann–Rahtz pyridine synthesis and the Hantzsch dihydropyridine synthesis can be carried out in a microwave flow reactor or using a conductive heating flow platform for the continuous processing of material. 
In the Bohlmann–Rahtz reaction, the use of a Brønsted acid catalyst allows Michael addition and cyclodehydration to be carried out in a single step without isolation of intermediates to give the corresponding trisubstituted pyridine as a single regioisomer in good yield. 
Furthermore, 3-substituted propargyl aldehydes undergo Hantzsch dihydropyridine synthesis in preference to Bohlmann–Rahtz reaction in a very high yielding process that is readily transferred to continuous flow processing.

Mark C. Bagley¹, Vincenzo Fusillo², Robert L. Jenkins², M. Caterina Lubinu² andChristopher Mason³

¹Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QJ, UK
²School of Chemistry, Main Building, Cardiff University, Park Place, Cardiff, CF10 3AT, UK
³CEM Microwave Technology Ltd, 2 Middle Slade, Buckingham, MK18 1WA, UK

This article is part of the Thematic Series "Chemistry in flow systems III".

Guest Editor: A. Kirschning

Beilstein J. Org. Chem. 2013, 9, 1957–1968.

Peering Inside Reactors Analytical Chemistry: Microspectroscopy tracks multistep process in action

read all at

http://cen.acs.org/articles/92/i9/Peering-Inside-Reactors.html
 

It’s tough to get a detailed account of what’s going on inside catalytic chemical reactors while those workhorse pieces of equipment are running. If researchers could peer inside and monitor—at a microscopic level and in real time—the chemical reactions under way, they would gather a treasure trove of useful information. Engineers could then customize reactor geometry and dimensions and tailor the catalyst distribution to maximize energy efficiency, product output, and chemical selectivity.

That type of custom reactor engineering may be close at hand, thanks to a study conducted by researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory.

The team designed a miniature reactor whose interior can be probed microscopically with infrared and X-ray beams. They used it to interrogate a multistep chemical reaction with extreme spatial resolution. The group pinpointed to within 15 μm the regions inside the reactor in which a flowing starting material was transformed to an initial product and then a final product. They correlated that information with the microscopic location, concentration, and chemical state of catalytic nanoparticles (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja412740p).

Larvicidal isoxazoles: Synthesis and their effective susceptibility towards Aedes aegypti larvae

................

Larvicidal isoxazoles: Synthesis and their effective susceptibility towards Aedes aegypti larvae

 
 

Bioorganic & Medicinal Chemistry

Volume 21, Issue 4, 15 February 2013, Pages 940–947

Diana C.B. da Silva-Alves, Janaína V. dos Anjos, Nery N.M. Cavalcante, Geanne K.N. Santos, Daniela M.do A.F. Navarro, Rajendra M. Srivastava

 Twenty 3,5-disubstituted isoxazoles have been synthesized and tested against fourth instar Aedes aegyptilarvae. In the synthesis of title compounds, modifications have been made in the C-5 side-chain with a view to test their larvicidal activity. These isoxazoles have been obtained by 1,3-dipolar cycloaddition of arylnitrile oxides to terminal alkynes which furnished the desired products in 20% to 79% yields. A comparative study of the larvicidal activity between 3-(3-aryl-isoxazol-5-yl)-propan-1-ols and 3-(3-aryl-isoxazol-5-yl)-propionic acids clearly demonstrated that the latter compounds possess much better larvicidal activity than the former. We also tested two esters, viz., methyl 3-[3-(phenyl)-isoxazole-5-yl] propionate and methyl 3-[3-(4-chlorophenyl)-isoxazole-5-yl] propionate, where the latter presented an excellent larvicidal profile.

The FDA’s Drug Review Process: Ensuring Drugs Are Safe and Effective « New Drug Approvals

The FDA’s Drug Review Process: Ensuring Drugs Are Safe and Effective « New Drug Approvals:



'via Blog this'

The FDA’s Drug Review Process: Ensuring Drugs Are Safe and Effective « New Drug Approvals

The FDA’s Drug Review Process: Ensuring Drugs Are Safe and Effective « New Drug Approvals:



'via Blog this'

Catalyst Under Stress

 
The oxidation of water to molecular oxygen is an important reaction in the frame of artificial photosynthesis, solar fuels, and a sustainable energy future. Iridium complexes have recently gained attention as effective precatalysts for this transformation. 

To gain deeper understanding of this process, Alceo Macchioni, University of Perugia, Italy, and colleagues aimed at intercepting the intermediates of the oxidative transformation of [Cp*Ir(bzpy)NO₃] (Cp* = pentamethylcyclopentadienyl, bzpy = 2-benzoylpyridine), which is a competent catalyst for water oxidation.
read at
http://www.chemistryviews.org/details/ezine/5838331/Catalyst_Under_Stress.html

Make a macroring in half a day instead of several months

Make a macroring in half a day instead of several months. 

INTRODUCTION

Macrocycles are not only esthetically pleasing, but they also can contain multiple functional groups. They are, however, difficult to synthesize. For example, preparing sterically crowded, circularly folded aromatic pentamer 1 required a months-long step-by-step process; and it was obtained in an overall yield of only ≈5%

(Qin, B., et al. Org. Lett. 2008, 10, 5127–5130).

The task is much easier now; it can be accomplished in half a day by using a synthetic route developed by H. Zeng and coauthors at the National University of Singapore, Guang Dong University of Technology (China), and Nanyang Technological University (Singapore).

 One-pot, multi-molecular macrocyclization allows the highly selective preparation of pentagon-shaped circular aromatic pentamers mediated by an inward-pointing continuous hydrogen-bonding network.

The protocol is based on a hydrogen-bonding–assisted, one-pot macrocyclization reaction. In the presence of coupling reagent POCl3 and organic base Et3N, 3-amino-2-methoxybenzoic acid (2) undergoes self-amidation under mild conditions to give 1 in a high yield (46%) after a 12-h reaction time. The versatility of this highly selective macrocyclization reaction is illustrated by synthesizing derivatives of 2 with various substituents at the 2- and 5-positions. (Chem. Commun. 2011, 47, 5419–5421;

 http://pubs.rsc.org/en/content/articlelanding/2011/CC/C0CC05791F#!divAbstract

--

THANKS AND REGARD'S
DR ANTHONY MELVIN CRASTO Ph.D

amcrasto@gmail.com

MOBILE-+91 9323115463

GLENMARK SCIENTIST ,  INDIA
web link

ABOUTME

BRAND ANTHONYCRASTO

COLLECTION OF SITE LINKS

http://amcrasto.bravesites.com/

http://anthonycrasto.jimdo.com/

Congratulations! Your presentation titled "Anthony Crasto Glenmark scientist, helping millions with websites" has just crossed MILLION views.

アンソニー     安东尼   Энтони    안토니     أنتوني

join my process development group on google

organic-process-development group

you can post articles and will be administered by me on the google group which is very popular across the world

https://sites.google.com/site/amcrasto/

SKILLPAGES

MIXXT

APNACIRCLE

LinkedIn group

SYNTHETIC ORGANIC CHEMISTRY

 
blogs are 

• Green Chemistry International,  
• Eurekamoments in Organic Chemistry ,   
• WIX CHEMISTRY BLOG , 
• Drug regulatory affairs international 
• ORGANIC CHEMISTRY SELECT
• ORGANIC SPECTROSCOPY INTERNATIONAL 
• ORGANIC SYNTHESIS INTERNATIONAL 
• ORGANIC CHEMISTRY INTERNATIONAL

MY BLOG ON MED CHEM

New Drug Approvals

ALL ABOUT DRUGS

WORLD DRUG TRACKER

MEDICINAL CHEM INTERNATIONAL

DRUG SYN INTERNATIONAL

SCALEUP OF DRUGS

ALL FOR DRUGS ON WEB

http://scholar.google.co.uk/citations?user=bxm3kYkAAAAJ