Reduction trans-cinnamaldehyde

The useful chemoselective feature of the reaction is apparent from the reduction of trans-cinnamaldehyde (cinnamaldehyde/NaBH4-alumina, 1 1 mol equivalent) olefmic moiety remains intact and only the aldehyde functionality is reduced in a facile reaction. 

Several water-soluble ruthenium complexes, with P = TPPMS, TPPTS, or PTA ligands (cf. Section 2.2.3.2), catalyze the selective reduction of crotonaldehyde, 3-methyl-2-butenal (prenal), and trans-cinnamaldehyde to the corresponding unsaturated alcohols (Scheme 2) [33—36]. Chemical yields are often close to quantitative in reasonable times and the selectivity toward the aUyhc alcohol is very high (> 95%). The selectivity of the reactions is critically influenced by the pH of the aqueous phase [11] as well as by the H2 pressure [37]. The hydrogenation of propionaldehyde, catalyzed by Ru(II)/TPPTS complexes, was dramatically accelerated by the addition of inorganic salts [38], too. In sharp contrast to the Ru(II)-based catalysts, in hydrogenation of unsaturated aldehydes rhodium(I) complexes preferentially promote the reaction of the C=C double bond, although with incomplete selectivity [33, 39]. 

A [3+3]-type condensation of O-acetyl ketoximes and a, -unsaturated aldehydes yields pyridines " for example, Ph-(Me)C=N-OAc and trans-cinnamaldehyde (trans-Ph-CH=CH-CHO) give 2,4-diphenylpyridine (54) using copper(I) iodide as catalyst and a salt of a secondary amine only a trace of the 2,6-product is observed. A synergistic copper/iminium catalysis is proposed the oxime reacts with the copper iodide to give an iminyl copper species, Ph-(Me)C=N-Cu-X (i.e., N-O reduction), which tautomerizes to a copper(II) enamide, Ph-C(=CH2)-NH-CuX, which then acts as a nucleophile towards the iminium ion (formed from the aldehyde and 2° amine). 

An alcoholic extract of cinnamon, cinnamon oil, and cassia oil have shown in vitro mutagenic activity (de smet et al.). However, a recent test of the essential of C. cassia found no mutagenic activity in the Ames test. Cinnamaldehyde is also reported to have mutagenic and both in vitro (Ames test, micronucleus test, and bone marrow chromosomal aberration assay) and in vivo antimuta-genic activities. Microencapsulated trans-cinnamaldehyde failed to produce neoplasms in rats after 2 years of exposure to 1000,2100, and 4100 ppm in their feed. Reductions in body weights were seen in rats exposed to 4100 ppm and in mice from 2100 ppm. The oral LD50 of cinnamaldehyde in mice is 2225mg/kg. ... 

Chiral centers, more than one, lljf Chiral stereomer, 69 Cholesterol, chirality in, 81 Cinnamaldehyde, 328 Cis-trans interconversion, 111 Cis-trans isomerism, in cyclic compounds, 163 Claisen condensation, 394 rearrangement, 439 Cleavage, oxidative, 117 Clemmensen reduction, 219, 311 Coenzyme A, 354 Collins reagent, 264 Collision frequency, 39 Configuration, 72 relative, 76 Conformation, 51 Conformational diastereomers, 78 enantiomers, 78 stereomers, 78... 

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