Cinnamaldehyde borohydrides

Reduction of the double bond only was achieved by catalytic hydrogenation over palladium prepared by reduction with sodium borohydride. This catalyst does not catalyze hydrogenation of the aldehyde group [31]. Also sodium borohydride-reduced nickel was used for conversion of cinnamaldehyde to hydrocinnamaldehyde [31]. Homogeneous hydrogenation over tris(triphenylphosphine)rhodium chloride gave 60% of hydrocinnamaldehyde and 40% of ethylbenzene [5(5]. Raney nickel, by contrast, catalyzes total reduction to hydrocinnamyl alcohol [4S. Total reduction of both the double... 

High yields of cinnamic alcohol can be obtained by reduction of cinnamaldehyde with alkali borohydrides. Formation of dihydrocinnamic alcohol is thus avoided [146]. 

UV spectra of neutral solutions of ALCELL lignins exhibited maximum at 205-210 nm and at 275-281 nm which are characteristic of other lignin preparations. Alkali-neutral difference spectra exhibited three maxima at about 252-254 nm, 296-300 and 363-366 nm which indicate the presence of aromatic hydroxyl, a-conjugated hydroxyls, and conjugated carbonyl groups. The latter includes carbonyl groups in the a-position as well as those in cinnamaldehyde units mentioned above. The alkali-neutral difference spectrum of ALCELL lignins reduced with sodium borohydride shows an almost complete elimination of the peak at 360-366 nm and an increase... 

The relatively inexpensive and safe sodium borohydride (NaBH4) has been extensively used as a reducing agent because of its compatibility with protic solvents. Varma and coworkers reported a method for the expeditious reduction of aldehydes and ketones that used alumina-supported NaBH4 and proceeded in the solid state accelerated by microwave irradiation (Scheme 7) [50]. The chemoselectivity was apparent from the reduction of frarcs-cinnamaldehyde to afford cinnamyl alcohol. 

It is a reducing agent similar in reactivity and selectivity to sodium borohydride. It is readily soluble in tetrahydrofurane, diethylene glycol dimethyl ether, and ethanol, slightly soluble in water or carbon tetrachloride, and insoluble in ether or benzene. Cinnamaldehyde is reduced by the reagent in tetrahydrofurane to cinnamyl alcohol in 94% yield. 

Aminopyridine condenses with cinnamaldehyde in the presence of anhydrous zinc chloride to give a product that, on treatment with sodium borohydride, gives 2-cinnamylaminopyridine similarly, various 2-(substituted-cinnamyl)aminopyridines are prepared from 2-aminopyridine and substituted cinnamaldehydes. When 2-aminopyiidine and formylferrocene are boiled under reflux in toluene containing phosphorus oxychloride, there is isolated a product which, when reduced with sodium borohydride, gives 2-pyridylamino-methyl ferrocene. ... 

In this section, you will prepare N-cinnamyl-m-nitroaniline (9) by a sequence beginning with the condensation of cinnamaldehyde (5) with nx-nitroaniline (6), followed by reduction of the intermediate imine 7 with sodium borohydride, as shown in Equations 17.12-17.14. The formation of the imine is reversible, but the reaction is driven to completion by azeotropic distillation. Because cyclohexane and water form a minimum-boiling azeotrope (Sec. 4.4), the water generated by the condensation of 5 and 6 is continuously removed by distilling the cyclohexane-water azeotrope throughout the course of the reaction. 

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