Microwave promoted synthesis

Microwave-Promoted Synthesis of Bicyclic Pyrimidine Derivahves... 

Tejedor and coworkers have utilized a combination of two domino processes for a microwave-promoted synthesis of tetrasubstituted pyrroles [344]. The protocol combines two coupled domino processes the triethylamine-catalyzed synthesis of enol-protected propargylic alcohols and their sequential transformation into pyrroles through a spontaneous rearrangement from 1,3-oxazolidines (Scheme 6.183). Overall, these two linked and coupled domino processes build up two carbon-carbon bonds, two carbon-nitrogen bonds, and an aromatic ring in a regioselective and efficient manner. The tetrasubstituted pyrroles could be directly synthesized from the enol-protected propargylic alcohols and the primary amines by microwave irradia-... 

These examples of Knoevenagel condensations illustrated that reaction times could be reduced from 1-2 days to 30-60 min by employing parallel microwave-promoted synthesis in open vessels, without affecting the purity of the resin-bound products. 

Scheme 7.34 Microwave-promoted synthesis of urea-derivatives on solid-support (purity based on crude 1H NMR purified yields on initial loading (0.73 mmol g-1)of alkyl safety-catch linker).

Scheme 1 Microwave-promoted synthesis of N-aryl pyrrolidines in neat water...

Scheme 14 Microwave-promoted synthesis, enzyme inhibition, and antiviral activity of Pl -elongated tertiary alcohol-containing HIV-1 protease inhibitors...

Sridhar and co-workers [192] have described a microwave-promoted synthesis of 2-aminothiophenes 146 by reaction of a ketone with a nitrile and elemental sulfur using KF-alumina as a base via multicomponent condensation reaction. This method offers an efficient and convenient modification to the Gewald reaction replacing organic base with KF-alumina (Scheme 111). 

A highly regioselective microwave promoted synthesis of 2-aryl-6-chloro-benzothiazoles (xxxviii) by the Suzuki-Miyaura coupling reaction of 2,6-dic-hlorobenzothiazole with arylboronic acids is given by Heo et al. [58]. 

Hakala U, Waehaelae K (2006) Microwave-promoted synthesis of polyhydroxydeoxybenzoins in ionic hquids. Tetrahedron Lett 47 8375-8378... 

A limited number of reports have appeared in the literature showing the use of water as a solvent for the microwave-promoted synthesis of thermoplastics. An example is the synthesis of water-borne polyimides using the standard polycondensation reaction of a dianhydride with a diamine (Seheme 3.1). In a scientific microwave unit, polymers with high molecular weights (Af up to 35.460 g/mol) were obtained within 22 min of heating using a one-pot two-step procedure. The dianhydride was first hydrolyzed in water to obtain the corresponding tetracarboxylic acid. This was then condensed with the diamine. The obtained polymers were completely comparable in their chemical and thermal properties to those obtained by conventional polymerization in m-cresol as solvent. 

The majority of reports concerning the microwave-promoted synthesis of metal complexes describe ligand substitution reactions. A variety of ligands containing different numbers of donor atoms have been used, but ligands with nitrogen donor atoms are by far... 

Figure 9.13 Microwave-promoted synthesis of benzo[/i]quinolines using ln(OTf)3, as described by Sarmah et al. [103].

Microwave-Promoted Synthesis of Bicydic Pyrimidine Derivatives... 

S. Mallakpour, S. Habibi, Microwave-promoted synthesis of new optically active poly (ester-imide)s derived from N, N -(p3Tomellitoyl)-bis-L-leucine diacid chloride and aromatic diols. Europ. Poly. J. 39, 1823-1829 (2003)... 

Scheme 9.27 Microwave-Promoted Synthesis of 9-Substituted Xanthenes.

This methodology afforded a suitable route to heterocycles, which were mainly prepared through multiple steps requiring long reaction times or harsh conditions. In addition to the use of unconventional solvents, microwave irradiation also allows the possibility of conducting reactions in the solid phase, that is, under solventless conditions. Dandia et al. (2006) reported a microwave promoted synthesis of... 

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