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An Efficient One-Pot Synthesis of Isoxazolyl Polyhydroquinolines via Hantzsch Condensation Using L-Proline as Catalyst.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Rajanarendar, Eligeti Reddy, Modugu Nagi Raju, Sirisilla |
| Copyright Year | 2011 |
| Abstract | 4-Substituted-1,4-dihydropyridines (1,4-DHPs) are well known as calcium channel modulators and have emerged as one of the most important classes of drugs for the treatment of caridiovascular diseases 1 , as exemplified by therapeutic agents such as Nifedipine, Nitrendipine and Nimodipine 2 . Hantzsch reported the synthesis of 1,4-dihydropyridines for the first time by one-pot, four component condensation of ethylacetoacetate (two moles), aromatic aldehyde and ammonia 3 . The Hantzsch synthesis was originally conducted either in acetic acid or in ethanol for long periods, which resulted in low yield of the products. Replacement of ammonia by ammonium acetate in Hantzsch synthesis high yields in short reaction periods and it can be carried out either in aqueous medium or under solvent free conditions 4 . Significant rate and yield enhancements were also noticed under microwave irradiation 5 . The utilization of cyclic 1,3diketone in one of the component in Hantzsch reaction is recently reported by using ionic liquids 6 , HClO4-SiO2 (Ref 7), metal triflate, Yb(OTf)3 (Ref 8), iodotrimethyl silane (TMSI) 9 , HY-Zeolite 10 , ceric ammonium nitrate 11 , I2 (Ref 12) and polymers 13,14 . However, the use of high temperatures, expensive metal precursors, catalysts that are harmful to environment and longer reaction times limit the use of these methods. Therefore, the search for a better catalyst for the synthesis of polyhydroquinoline derivatives using less hazardous catalytic method is of prime importance. L-Proline is a bi-functional chiral organo-catalyst which is inexpensive, efficient, readily available and facilitates chemical transformations in concert similar to enzymatic catalysis by acting as an acid or base 15 . It has been extensively used in the synthesis of variety of heterocycles and also in aldol, Mannich and Michael reactions 16 . As the mechanism of multi-component Hantzsch reaction involves aldol related reactions, the use of L-proline for the same is quite useful. As a sequel to the interest in developing novel synthetic methodologies 17 , a study of the utility of L-proline as an efficient organo-catalyst for the synthesis of polyhydroquinoline derivatives was undertaken. |
| File Format | PDF HTM / HTML |
| DOI | 10.1002/chin.201138145 |
| Alternate Webpage(s) | http://nopr.niscair.res.in/bitstream/123456789/11696/1/IJCB%2050B(5)%20751-755.pdf |
| Alternate Webpage(s) | https://doi.org/10.1002/chin.201138145 |
| Volume Number | 42 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
