Synthesis of diverse dihydropyrimidine-related scaffolds by fluorous benzaldehyde-based Biginelli reaction and post-condensation modifications

• Bruno Piqani and
• Wei Zhang

Beilstein J. Org. Chem. 2011, 7, 1294–1298, doi:10.3762/bjoc.7.150

• achieved by conducting a multicomponent reaction for improved atom economy, under microwave heating for fast reaction, and with fluorous solid-phase extractions (F-SPE) for ease of purification. Keywords: Biginelli reaction; dihydropyrimidine; diversity-oriented synthesis; fluorous; Suzuki coupling

• intermediate for post-condensation reactions including cycloaddition, Liebeskind–Srogl reaction and Suzuki coupling to form three different heterocyclic skeletons. The high efficiency of the diversity-oriented synthesis was achieved by conducting fast, microwave-heated reactions and simple fluorous solid-phase

• extractions (F-SPE) for purification [7]. The perfluorooctanesulfonyl group served as a phase tag for F-SPE and also as a convertible linker for the Suzuki coupling to introduce biaryl functionality to the heterocyclic skeletons [8][9][10][11][12]. Result and Discussion Fluorous benzaldehydes 1 were prepared

Solvent-free phase-vanishing reactions with PTFE (Teflon^®) as a phase screen

• Kevin Pels and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2009, 5, No. 75, doi:10.3762/bjoc.5.75

• benefits in using heavier liquid perfluoro compounds as phase screens [19]. Gladysz used Teflon® tape to deliver and recover a fluorous catalyst [20]. Recently, we reported preliminary results on use of a solid perfluoro compound, PTFE (polytetrafluoroethylene, Teflon®) tape, as a phase screen between the

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed- bed microreactor

• Andrew Bogdan and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2009, 5, No. 17, doi:10.3762/bjoc.5.17

• leaching nor the need for catalyst regeneration [22]. Nitroxyl radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), immobilized on silicates [23][24][25][26][27][28][29][30][31][32], fluorous supports [33], soluble and insoluble polymers [22][34][35][36], magnetic nanoparticles [37], and ionic

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• 2004, Curran’s group [55] reported a 4-mix/4-split strategy for the synthesis of a stereoisomer library of (+)-murisolin and 15 of its isomers, which relied on solution phase technique of fluorous mixture synthesis (Scheme 17). In their synthetic route, a single mixture of M-119, which was tagged with

• different fluorous PMB tags, was transformed into alkene M-120 and was then followed by two splits. First, each of the two mixtures was subjected to a Shi epoxidation with enantiomeric ketone catalysts. Later, these two mixtures were split again, half being subjected to a Mitsunobu reaction and the other

Synthesis of deep- cavity fluorous calix[4]arenes as molecular recognition scaffolds

• Maksim Osipov,
• Qianli Chu,
• Steven J. Geib,
• Dennis P. Curran and
• Stephen G. Weber

Beilstein J. Org. Chem. 2008, 4, No. 36, doi:10.3762/bjoc.4.36

• Maksim Osipov Qianli Chu Steven J. Geib Dennis P. Curran Stephen G. Weber Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA, Fax: +1-412-624-9861; Tel: +1-412-624-8240 10.3762/bjoc.4.36 Abstract Several lower-rim perfluoroalkylated (fluorous) calix[4]arenes

• have been synthesized by O-alkylation of the parent calix[4]arene. The compounds are formed in the cone conformation. They are soluble in several fluorous solvents and show promise for use in sensing, selective extractions and other applications. Keywords: calixarene; fluorous; hydrofluoroethers

• calixarene can be tailored to bind preferentially with specific target guest molecules. Fluorous chemistry [13] has become an increasingly popular field as a result of the multitude of applications that it has provided across the disciplines of chemistry. Fluorocarbons are extraordinarily non-polar and are

Phase- vanishing halolactonization of neat substrates

• Nicole Windmon and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2008, 4, No. 29, doi:10.3762/bjoc.4.29

• products form, which encase the stirring bar. A result is that, if not clamped, the entire vial may begin to rotate and it may flip over. Usually, solubility of the reaction products in FC-72 is negligible and it can be reused. However, one should always check the fluorous phase for presence of the product

• were done in glass vials of various sizes (4–20 mL). Halogen (2.2–30.0 mmol) was added first, followed by of FC-72 (0.5–5 mL) and finally 2.0–25.0 mmol of an alkene. After stirring for 20 min – 3 days, the product was isolated by separating it from the fluorous phase either by filtration (solid

• products) or by removing the fluorous phase with a pipette. Bromolactonization of 4-pentenoic acid. Bromolactonization of 4-pentenoic acid in ethyl acetate. Iodolactonization of 4-pentenoic acid. Bromolactonization of 5-norbornene-2-carboxylic acid. Phase-vanishing halolactonization. Supporting

Themed series in organo- fluorine chemistry

• David O'Hagan

Beilstein J. Org. Chem. 2008, 4, No. 11, doi:10.3762/bjoc.4.11

• a result of accumulating crystallographic data of protein-drug interactions [8]. Exploring the role and nature of fluorous molecules has been an intense area of research internationally [9], one which has had a relatively short lead time since the seminal paper of Horváth and Rábai in 1994 [10]. In