Phenylprop-2-enal

This provides a route to a/3-unsaturated aldehydes (25). 2-Methyl-3-phenylprop-2-enal (25)... 

Methoxytrimethylsilane, 123 Methyl acetoacetate, 92 Methyl bromoacetate, 107 Methyl 11-hydroxyundecanoate, 58 Methyl lithium, 27,28 Methyl 10-undecenoatc, 58 2-MethyM,3-dithiane, 81 (V f ,55)-Methyl-3-phenyldimethyl-silyl-3-phenylpropionic acid. 53-4 2-Methyl-3-Phenylprop-2-enal, 111 2-Methyl-2-trimethylsilyl-l,3-dithiane, 81 2-Methyl-l-(trimethylsilyloxy)cydo-hex-l-ene, 100,109 2-Methyl-l-trimethylsilyloxy-cyclo-hex-6-ene, 100... 

Very few enzyme-catalysed reactions involving the reduction of alkenes have achieved any degree of recognition in synthetic organic chemistry. Indeed the only transformation of note involves the reduction of a, (3-unsaturated aldehydes and ketones. For example, bakers yeast reduction of (Z)-2-bromo-3-phenylprop-2-enal yields (S)-2-bromo-3-phenylpropanol in practically quantitative yield (99 % ee) when a resin is employed to control substrate concen-tration[50]. Similarly (Z)-3-bromo-4-phenylbut-3-en-2-one yields 2(5), 3(,S)-3-bromo-4-phenylbutan-2-ol (80% yield, >95% ee)[51]. Carbon-carbon double bond reductases can be isolated one such enzyme from bakers yeast catalyses the reduction of enones of the type Ar—CH = C(CH3)—COCH3 to the corresponding (S)-ketones in almost quantitative yields and very high enantiomeric excesses[52]. 

Cinnamic aldehyde (3-phenylprop-2-enal) This is not a terpene derivative but is an example of an aldehyde. Found in essential oils of cinnamon bark, cassia (Chinese cinnamon). Warm, spicy and balsamic. 

Benzaldehyde yielded no dibenzyl ditellurium. In the reation with 3-phenylprop-2-enal the double bond was hydrogenated and bis[3-phenylpropyl ditellurium was isolated in 48% yield. Ketones reacted only sluggishly under these conditions. Cyclohexanone gave dicyclohexyl ditellurium in a yield of only 11%. 

Then, the stereoselective substitution reaction of cation (42) by water generated 1-phenyl prop-2-en-l-ol (44) and/or ( )-3-phenylprop-2-en-l-ol (45). Finally, (37) assisted by FeCl2 oxidized (44) or (45) to the product (ii)-3-phenylprop-2-enal (46). The cleavage of the allyl sp C-H bond in the rate-determining step was supported... 

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