Methylcinnamate, formation

Brick et al. have studied this bromination in more detail and showed that the extent of the bromination can be controlled by changing the ratio of the reagents. The first substitution was found to be in the para position but subsequent intramolecular rearrangements allowed the formation of 2-5-dibrominated species. Brick et al. also reported the functionalization of such species using Pd-catalyzed reactions such as Heck and Suzuki couplings to give fully substituted p-stilbenes, p-biphenyls, diarylamines, and methylcinnamates. Hydrogenation of... 

Neither tritium or deuterium gas, with zero dipole moments, can be expected to interact positively with microwave radiation. Their low solubilities are seen as a further disadvantage. Our thoughts therefore turned towards an alternative procedure, of using solid tritium donors and the one that has found most favor with us is formate, usually as the potassium, sodium or ammonium salt. Catalytic hydrogen transfer of this kind is remarkably efficient as the results for a-methylcinnamic acid show [50]. The thermal reaction, when performed at a temperature of 50 °C, takes over 2 h to come to equilibrium whereas the microwave-enhanced reaction is complete within 5 min. A further advantage is that more sterically hindered al-kenes such as a-phenylcinnamic acid which are reduced with extreme difficulty when using H2 gas and Wilkinson s catalyst are easily reduced under microwave-enhanced conditions. 

The 1-t-butylphospholane sulfide intermediate to TangPhos was also used to prepare the P,N ligands 48 by reacting the lithium complex with C02 and then oxazoline formation with a range of chiral amino alcohols [69b, 74]. The Ir complexes of these ligands have been successfully used in the reduction of / -methylcinnamic esters (80-99% ee) and methylstilbene derivatives (75-95% ee), a particularly challenging class of unfunctionalized olefins [4 c]. 

Another very common use of phenolic compounds is in sunscreens. The presence of the aromatic ring results in the effective absorbance of the UV-B radiation (between 280 and 315 nm) from the sun and thus prevents sunburns. The most common active ingredient in many sunscreens is p-aminobenzoic acid (PABA 7.1), which is actually not a phenolic compound. This compound has been widely used since the 1970 s but is less popular nowadays due to the formation of skin rashes and acne. As a result many sunscreens are now PABA-free. Alternative active ingredients include salicylates such as octylsalicylate (7.2), cinnamates such as octyl methylcinnamate (7.3), benzophenone (7.4) and the related compound oxybenzone (7.5), and anthranilates, such as menthylanthranilate (7.6). Octyl methylcinnamate (7.3) is insoluble in water and is therefore commonly... 

The molecular motions in inclusion complexes formed by cyclohexa-amylose with 4-methylcinnamate, 3-methylcinnamate, and 4-t-butylphenate anions have been studied by and nuclear relaxation methods. The results showed that the time taken for the substrate to reorientate increases by a factor of ca. 4 on inclusion, whereas the increase in tumbling motion depends on the substrate. It was pointed out that, in general, a molecular complex should be described not only by its thermodynamic stability and formation and dissociation kinetics, but also by the dynamic rigidity, defined by the coupling between the molecular motions of the two (or more) entities of which it is composed. 

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