Microwave organic reaction enhancement

Microwave organic reaction enhancement (MORE) chemistry was described by Bose as a safe and convenient alternative to pressure reactions and modified microwave ovens [20]. 

Shiradkar et al. [19] reported the synthesis of clubbed thiazolyl triazole derivatives (vii) starting from ethyl acetoacetate, by microwave organic reaction enhanced method (MORE). The synthesized triazoles showed promising antimicrobial and antimycobacterial activities. 

Many organic reactions can be conducted very rapidly under microwave irradiation. Microwave-induced organic reaction enhancement chemistry techniques were used for the rapid formation of an ot-benzyloxy-p-lactam (10 in Fig. 4.2) and the hydrogenolysis of its benzyloxy group on a few-gram scale in 1-5 minutes with HC02NH4 and Pd/C in ethylene glycol as the reaction medium in a domestic microwave oven.243... 

Microwave-induced organic reaction enhancement chemistry was used for the hydrogenolysis of the C-N bond in lactams. To a solution of a-vinyl (3-lactams in ethylene glycol were added HC02NH4 and 10% Pd/C catalyst then this mixture was irradiated in a microwave oven (Scheme 4.108).357... 

Bose, A.K. and Manhas, M.S., Banik, B.K. and Robb, E.W., Microwave-induced organic-reaction enhancement (MORE) chemistry - techniques for rapid, safe and inexpensive synthesis, Res. Chem. Intermed., 1994, 20, 1-11. 

Banik, B.K., Manilas, M.S., Kaluza, Z., Barakat, K.J. and Bose, A.K., Microwave-induced organic-reaction enhancement chemistry 4. Convenient synthesis of enantiopure ct-hydroxy-p Iaclams, Tetrahedron Lett., 1992, 33, 3603. 

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]. 

If the product is needed on a small scale, up to 100 g, the reaction can be scaled out rather than scaled up. The excellent reproducibihty together with automation can easily produce up to 100 g overnight. Bose et al. have described an alternative for minor scale-up where the use of the microwave-assisted organic reaction enhancement (MORE) technique reduces the need for organic solvents and increases atom economy by improving product selectivity and chemical yield, thus, minimizing the need for larger scale-up. 

By using the microwave-induced organic reaction enhancement (MORE) method Balasubramanian et al. [41] achieved solvent-free glycosylations by treating tri-O-acetyl-D-glucal 49 with substituted phenols to afford 2,3-unsaturated O-aryl glycosides 50 reaction times reduced several fold compared with those required under thermal conditions (Scheme 12.24). 

Differential heating is more easily achieved with microwave technology than by conventional conductive methods and as Cundy suggested in his excellent review, could well account for apparent rate enhancements obtained by others with organic reactions on dry media [40]. 

Most of these publications describe important accelerations of a wide range of organic reactions especially when performed under solvent-free conditions. The combination of solvent-free reaction conditions and microwave irradiation leads to large reductions in reaction times, enhancement of yield, and, sometimes [3, 4] in selectivity with several advantages of an eco-friendly approach, termed green chemistry . 

Microwave processing of zeolites and their application in the catalysis of synthetic organic reactions has recently been excellently reviewed by Cundy [23] and other authors [24], The microwave synthesis of zeolites and mesoporous materials was surveyed, with emphasis on those aspects which differ from conventional thermal methods. The observed rate enhancement of microwave-mediated organic synthesis... 

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