Translation of microwave methodology to continuous flow for the efficient synthesis of diaryl ethers via a base-mediated S_NAr reaction

• Charlotte Wiles and
• Paul Watts

Beilstein J. Org. Chem. 2011, 7, 1360–1371, doi:10.3762/bjoc.7.160

• ] describing the use of scCO2, and Moseley et al. [15] employing microwave irradiation as a means of efficiently heating the reaction mixture in order to significantly reduce reaction times (Scheme 1). Although microwaves have found widespread application in the research laboratory, their implementation at a

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths

• Ping He,
• Stephen J. Haswell,
• Paul D. I. Fletcher,
• Stephen M. Kelly and
• Andrew Mansfield

Beilstein J. Org. Chem. 2011, 7, 1150–1157, doi:10.3762/bjoc.7.133

• [12][13]. To this end, the use of microwave heating in conjunction with microporous monolithic reactors has attracted some interest for small-scale synthesis under continuous-flow conditions [14][15][16]. One obvious problem, however, when using microwaves to heat solvents/reagents and surface

• monolith diameter will become larger than the penetration depth of the microwaves (estimated to be 4 cm), which will lead to an unheated, cold “core”. In addition for disc-shaped monoliths, where diameters are larger than the length, there will also come a point where the mechanical strength of the

Complete transfer of chirality in an intramolecular, thermal [2 + 2] cycloaddition of allene-ynes to form non-racemic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2011, 7, 601–605, doi:10.3762/bjoc.7.70

• , we were poised to test the transfer of chiral information under thermal [2 + 2] reaction conditions. Irradiation of 8 in o-dichlorobenzene with microwaves for 5 min at 225 °C provided the desired spirooxindole 9 in 44% yield (Scheme 3). Despite the somewhat low yield, the reaction is clean as judged

Synthesis and crystal structures of multifunctional tosylates as basis for star-shaped poly(2-ethyl-2-oxazoline)s

• Richard Hoogenboom,
• Martin W. M. Fijten,
• Guido Kickelbick and
• Ulrich S. Schubert

Beilstein J. Org. Chem. 2010, 6, 773–783, doi:10.3762/bjoc.6.96

• 25 and the desired monomer concentration is 1, 2 or 4 M. This polymerization mixture was heated by microwaves to the desired temperature for a fixed time (5 min at 140 °C; 2 min at 160 °C; 30 seconds or 10 min at 200 °C). After heating, the polymerization mixtures were investigated by size exclusion

Flow through reactors for organic chemistry: directly electrically heated tubular mini reactors as an enabling technology for organic synthesis

• Ulrich Kunz and
• Thomas Turek

Beilstein J. Org. Chem. 2009, 5, No. 70, doi:10.3762/bjoc.5.70

• heat exchangers. With the advent of microwave equipment, heating by microwaves was rapidly introduced as standard method in organic chemistry laboratories, mainly because of the convenient possibility to operate at high temperature accompanied by accelerated reaction rates. In the present contribution

• through reactors conveniently and rapid at low cost? Results and Discussion Heating concept In addition to microwaves, heating by other electromagnetic fields was recently introduced into organic synthesis. Magnetic particles were heated by the interaction with an electromagnetic field in the frequency

Microwave assisted synthesis of triazoloquinazolinones and benzimidazoquinazolinones

• Aboul-Fetouh E. Mourad,
• Ashraf A. Aly,
• Hassan H. Farag and
• Eman A. Beshr

Beilstein J. Org. Chem. 2007, 3, No. 11, doi:10.1186/1860-5397-3-11

• the preparation of structural variant of imidazoquinazolinones with three-point diversity. [20] The use of microwaves in organic synthesis has increased dramatically in the last years, receiving widespread acceptance and becoming an indispensable tool. [21] Microwave technology has become a powerful

Microwave- assisted ring closure reactions: Synthesis of 8-substituted xanthine derivatives and related pyrimido- and diazepinopurinediones

• Joachim C. Burbiel,
• Jörg Hockemeyer and
• Christa E. Müller

Beilstein J. Org. Chem. 2006, 2, No. 20, doi:10.1186/1860-5397-2-20

• reaction with hexamethyldisilazane was studied under microwave conditions. Reaction times were dramatically reduced by the application of microwaves in the syntheses of the 8-styrylxanthine derivative istradefylline, and in the preparation of 2-substituted pyrimido [1,2,3-cd]purines. Furthermore, the new

• microwave irradiation. Furthermore, we showed that application of microwaves considerably improves the cyclization step to obtain tricyclic pyrimido [1,2,3-cd]purinediones. 2-Substituted diazepino [1,2,3-cd]purinediones, that had previously not been accessible by thermal cyclization [6] could be obtained in