As noted above the primary mechanism for termination of action ..

Synthesis of barbituric acid, from the combination of malonic acid (left) and urea (right).
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Side Chain Differences between Barbituric Acid Derivatives.

Single-electron-transfer reactions open up unexplored reaction space charted with chemoselectivity and reactivity levels difficult to access by ionic reaction mechanisms. The generation of ketyl-type radicals with SmI2 is particularly valuable in this regard because of the excellent chemoselectivity imparted by the reagent and the potential to effect polarity reversal of the carbonyl group through a single-electron-reduction event (Figure )., However, the selective reduction of amide carbonyls with SmI2 is challenging and no general method to achieve this highly desirable transformation is currently available.

The major mechanism for removal of acetonitrile from the troposphere is reaction with hydroxyl radicals.
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Synthesis of Barbiturates - Erowid

Other activities carried out by the IPCS include the development of know-how for coping with chemical accidents, coordination of laboratory testing and epidemiological studies, and promotion of research on the mechanisms of the biological action of chemicals.

In our laboratory, the mechanism of ferulic acid transformation to vanillic acid by R
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A proposed mechanism is shown in Scheme . We hypothesize that the kinetic diastereoselectivity in the reduction results from the formation of an organosamarium(III) on the less hindered face of the molecule. This is analogous to the classic reduction of cyclic ketones to equatorial alcohols by related SmI2/H2O systems. In the reductive cyclization, the radical anion undergoes an anti addition to give the vinyl radical intermediate, which isomerizes, depending on the steric and electronic preferences of the π acceptor and the reaction conditions. Control experiments (see the Supporting Information) point to the critical role of H2O in stabilizing the radical anion and promoting cyclization (no reaction is observed in the absence or at low concentration of H2O as well as with more powerful SmI2-based reductants, SmI2/LiCl and SmI2/HMPA).

TY - JOUR T1 - Noncovalent synthesis of melamine - cyanuric/barbituric acid derived nanostructures: regio- and stereoselection AU - Timmerman,P. AU - Prins,L.J. N1 - 9. PY - 2001 Y1 - 2001 KW - METIS-203098 M3 - Article
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Insulin Sensitivity and Secretion

Herein, we demonstrate that the SmI2/H2O reagent can perform the selective monoreduction of barbituric acids to the corresponding hemiaminals (Figure ). To our knowledge these are the first general examples of monoreduction of such systems as well as the reduction of amide-type carbonyls with SmI2., The hemiaminal products are analogous to tetrahedral intermediates derived from amide addition reactions. Moreover, the radical intermediates formed by the one-electron reduction have been utilized in intramolecular additions to alkenes. For the first time in any SmI2-mediated cross-couplings of acyl-type radicals, these additions proceed with full control of diastereoselectivity. Furthermore, experimental evidence is provided for the isomerization of vinyl radical intermediates under SmI2/H2O reaction conditions. This discovery opens the door for the use of SmI2/H2O in cascade reductive processes employing C-centered radicals. Overall, these studies provide a basis for multiple methodologies to form versatile hemiaminal products (cf. hemiacetals) by a formal amide polarity reversal event.

Acetonitrile (EHC 154, 1993) - IPCS INCHEM

After extensive optimization of the reaction conditions, we determined that barbituric acids are reduced with SmI2/H2O to the corresponding hemiaminals in good yields and diastereoselectivities (Table ). Typically, a twofold excess of reagent was used to ensure that the reactions were complete. A wide range of substrates exhibited excellent reactivity, including those with sensitive α protons (entries 1–8), as well as those with sterically hindered quaternary centers (entries 9–11). Importantly, the method tolerates functional groups that are typically reduced under single-electron-transfer conditions, including aromatic rings (entries 4 and 5), ethers (entry 6), trifluoromethyl groups (entry 7), and halides (entry 8). The potential of the reaction to streamline synthetic routes by sequential reductive processes has also been demonstrated (entries 12 and 13). Several products bear close analogy to the pharmacologically active barbiturates (entry 3: amobarbital, entry 10: butalbital).

Controlled Substances Act from the U.S. DEPT. OF …

The CSA places all substances that are regulated under existing federal law into one of five schedules. This placement is based upon the substance's medicinal value, harmfulness, and potential for abuse or addiction. Schedule I is reserved for the most dangerous drugs that have no recognized medical use, while Schedule V is the classification used for the least dangerous drugs. The act also provides a mechanism for substances to be controlled, added to a schedule, decontrolled, removed from control, rescheduled, or transferred from one schedule to another.