Untitled

Abstract

A paradigm shift away from using solvents in organic synthesis as solventless reactions can lead to improved outcomes, and more benign synthetic procedures, in for example aldol condensation reactions, sequential aldol and Michael addition reactions en route to Kröhnke type pyridines, reactions leading to 3-carboxycoumarins, benzylidenes, 4-aryl-1,4-dihydropyridines and 2-aryl-1,2,3,4-tetrahydroquinazolines, and oligomerisation reactions for the synthesis of cavitands; kinetic considerations for the reaction of two solids can only be explained if a eutectic melt is formed during the reaction.

Solvent-free Substitution Reactions of Solid Phosphines with (η5-RC5H4)Fe(CO)2I (R = H, Me) Complexes

“…The simplest approach to environmentally benign chemical synthesis is to perform reactions in the absence of solvents. The solvent-free technique has been utilised in the synthesis of organic compounds [3], the processing of materials [4] and more recently to a study of organometallic reactions and transformations [5]. From the reported studies several advantages of solvent-free techniques have been documented, notably the possibility of synthesising novel products not readily produced by solution procedures [6].…”

“…By choosing substituted phosphines (same Tolman cone angle = 145 • [14]), the steric influence of the ligands in the reaction is kept constant. Hence, electronic factors will account for the changes in reactivity of the metal complexes with the various phosphine ligands [except P(m-Tol) 3 ]. Since ionic product formation followed a trend in reactivity R : Ph m-Tol ≈ p-C 6 H 4 OMe > p-C 6 H 4 F p-C 6 H 4 Cl it is clear that the donor ability of the ligand differentiates between CO or I replacement in the reaction -the better the donor ability the more the salt formed.…”

“…(ii) The 31 P NMR spectra of all the complexes confirmed the presence of a bound phosphine ligand by a singlet peak. The NMR peaks for the ionic products 2 range from 57.4 ppm for R = P(p-C 6 H 4 OMe) 3 to 61.8 ppm for PPh 3 , while the peaks for the neutral products 3 are observed slightly downfield (δ = 62.6 to 68.3 ppm). (iii) The IR spectra exhibit two well separated absorption peaks (∆ν 40 cm −1 ) for the two CO ligands at > 2000 cm −1 for all the salt complexes, and one CO absorption at ca.…”

“…For example, the substitution reaction of (η 5 -RC 5 H 4 )Fe(CO) 2 X complexes (R = organic substituent, X = halide) with electron donating ligands (isonitriles, phosphites and phosphines) is Ligand PR 3 Time Products of reaction with metal complex RCpFe(CO) 2 I (%) R (min) 2 = [RCpFe(CO) 2 The reaction was carried out with a 1 : 5 complex to ligand mole ratio at various temperatures. The reactions were monitored by 1 H NMR spectroscopy as described in the experimental section and at the end of the reaction the reaction mixture was cooled, and the products separated and isolated.…”

The utilization of copper/zeolite as catalyst in the microwave-assisted synthesis of some novel sulfonamide derivatives

“…Because the solvent free microwave method has more selectivity, easiest separation, higher yield, eases of isolation of product, less energy consumption than the conventional solvent methods, this method is used in industries to avoid large volume consumption of solvents [1]. In order to protect mesalazine (5-aminosalicylic acid) compound, sulfonyl chloride based nitrogen protecting method is easy to carryout.…”