Accelerators synthesis

Regarding the series of hetero aromatic pentacyclic compounds with three heteroatoms, an accelerated synthesis of 3,5-disubstituted 4-amino-1,2,4-triazoles 66 under microwave irradiation has been reported by thermic rearrangement of dihydro-1,2,4,5 tetrazine 65 (Scheme 22). This product was obtained by reaction of aromatic nitriles with hydrazine under microwave irradiation [53]. The main limitation of the method is that exclusively symmetrically 3,5-disubstituted (aromatic) triazoles can be obtained. 

Wannberg J, Ersmark K, Larhed M (2006) Microwave-Accelerated Synthesis of Protease Inhibitors. 266 167-197... 

P. Antoni, D. Nystrom, C. J. Hawker, A. Hult, and M. Malkoch, A chemose-lective approach for the accelerated synthesis of well-defined dendritic architectures, Chem. Commun. (2007) 2249-2251. 

Unfortunately, the presence of the benzylic alcohol moiety at the focal point of the dendrimer, along with the catalyst (used in the urethane formation) led to the formation of undesired side products, presumably due to carbamate interchange. These side reactions were avoided by switching to monomer 19, methyl-3,5-dihydroxybenzoate. While the carbamate linkages of dendrons 53 and 54 were too unstable under the alkylation conditions required to afford larger dendrons, the merits of the concept was adequately demonstrated for this accelerated synthesis of [G-3] dendrons. 

Blagden, N., and Davey, R., Polymorphs take shape, Chem. in Brit., March 1999, p. 44. Owen, M., and Dewitt, S., Laboratory Automation in Chemical Development. In Process Chemistry in the Pharmaceutical Industry (K.G. Gadamasetti, ed.), Marcel Dekker, Inc., New York 1999, pp. 429-455 Conner, K., The drive to improve the bottom line. Today s Chemist at Work, November 1999, p. 29. Sullivan, M., Automation accelerates synthesis. Today s Chemist at Work, September 1999, p. 48. Studt, T., Raising the bar on combinatorial discovery, Drug Discovery Development, January/February 2000, p. 24. Harness, J.R., Automated sample handling supports synthesis and screening. Drug Discovery Development, January 1999, p. 69. 

Figure 1.12 Target-accelerated synthesis of vancomycin dimers via olefin metathesis (n = 2 or 4).

Chebanov VA, Saraev VE, Desenko SM, Chernenko VN, Shishkin OV, Lukinova EV, Kappe CO (2007) Microwave-assisted and ultrasonic-promoted regio- and chemoselective three-component reactions of 3-aryl-6-aminopyrazoles, aldehydes and 1,3-diketones. 2nd symposium on microwave accelerated synthesis, Diisseldorf, Germany, 32... 

Bentiss, F., Lagrenee, M. and Barbry, D., Accelerated synthesis of 3,5-disustitued 4-amino-1,2,4-triazoles under microwave irradiation, Tetrahedron Lett., 2000,41, 1539-1541. 

Dasgupta, A., Banerjee, P. and Malik, S., Use of microwave irradiation for rapid transesterification of lipids and accelerated synthesis of fatty acyl pyrrolidides for analysis by gas chromatography-mass spectrometry study of fatty acid profiles of olive oil, evening primrose oil, fish oils and phospholipids from mango pulp,... 

A fundamental aspect of biochemical organizations is that the enzymes that catalyze a sequence are often clustered together in the cell. As a result, an intermediate produced in the first reaction in a pathway is passed directly to the second enzyme in the pathway, and so on. Such an arrangement might be expected to accelerate synthesis of the end product, minimize the loss of intermediates, and facilitate regulation of the pathway. 

Microwave-induced organic reaction enhancement chemistry techniques have been reported to allow highly accelerated synthesis of variously substituted vinyl-(3-lactams, using limited amounts of solvents and with efficient stereocontrol [3]. 

Scheme 57 Microwave-accelerated synthesis of 1,3,5-triazines in ionic liquid...

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