Cinnamaldehyde synthesis

ARENS VAN DORP Cinnamaldehyde Synthesis Synthesis ol cinnamaldehydes from aryl ketones... 

Combination of lipase-catalyzed transesterification with unsaturated vinyl esters as acyl donors and ring-closing metatheses (RCMs) have also been reported [146-148]. Two groups applied this strategy for the synthesis of goniothalamin from cinnamaldehyde [147,148]. The key steps were a transesterification using vinyl acrylate as acyl donor, followed by an RCM, as depicted in Figure 6.55. 

We have shown that the direct arylation of acrolein toward the synthesis of cinnamaldehyde derivatives was an efficient procedure. Using the palladacycle 1 as catalyst, substituted aldehydes 3 were prepared with up to 87% isolated yield from condensed aiyl bromides (Scheme 21.1, Route 1) that was extended successfully to heteroaiyl bromides, like bromoquinolines (6). Alternatively, the acrolein diethyl acetal was used as olefin and a selective formation of the saturated ester 4 was attained under the same reaction conditions (Scheme 21.1, Route 2). The expected aldehydes 3 were, however, obtained from most of the aiyl halides used under modified conditions. It was shown that the addition of n-Bu4NOAc in the medium... 

Hajek J, Maki-Arvela P, Toukoniitty E, Kumar N, Salmi T, Muizin DY (2004) The effect of chemical reducing agents in the synthesis of sol-gel Ru-Sn catalysts selective hydrogenation of cinnamaldehyde. J Sol-Gel Sci Technol 30 187-195... 

The second Had synthesis provided a route to 2,3,4-trisubstituted pyrroles <06CC2271>. Mixing cinnamaldehyde 27 with aminocarbene complex 28 in the presence of molecular sieves (MS) gave pyrrole 29. The authors proposed a mechanism that included a cyclopropane intermediate and subsequent fragmentation and intramolecular condensation. 

The stereoselective addition of the titanium enolate of A-acetyl-4-phenyl-l,3-thiazolidine-2-thione 153 to the cyclic A-acyl iminium ion 154 is utilized in the synthesis of (-)-stemoamide, a tricyclic alkaloid <06JOC3287>. The iminium ion addition product 155 undergoes magnesium bromide-catalyzed awtz-aldol reaction with cinnamaldehyde 156 to give adduct 157, which possesses the required stereochemistry of all chiral centers for the synthesis of (-)-stemoamide. 

The synthesis of y-lactams has been achieved under similar reaction conditions (Table 18) [124]. Initially, Bode and co-workers screened a variety of acyl imines in order to find suitable electrophiles. Control experiments provided evidence for carbene addition to the acyl imine, yielding a stable complex with complete inhibition of the desired reactivity. Reversibility of this addition was key to the success of the reaction. A -4-Methoxybenzenesulfonyl imines 212 proved to be the most efficient partners for lactamization with cinnamaldehydes 228 to provide y-lactams 229 in moderate yields and good diastereoselectivities. Notably, no benzoin or S tetter products or their corresponding derivatives were observed during this reaction. 

Our interest in the synthesis of deoxy- and deoxy-amino sugars of the L-series originates from studies (1 ) on the products obtained by the action of fermenting baker s yeasts on such aromatic, a,/9-unsaturated aldehydes as cinnamaldehyde (la) and a-methylcinnamaldehyde (lb ). The transformation proceeds as indicated in Eq. 

Photocyclization of the condensed adduct 56 between 2-methyl-4-oxoquinoline and cinnamaldehyde gives the acridine 57 <99ZN(B)1337>. This approach is notable for its application to the synthesis of the hitherto unknown 1-phenyl and 1-naphthacridones. 

Cinnamaldehyde is used in many compositions for creating spicy and oriental notes (e.g., soap perfumes). It is the main component of artificial cinnamon oil. In addition, it is an important intermediate in the synthesis of cinnamic alcohol and dihydrocinnamic alcohol. 

With benzaldehyde 144 or halogenated derivatives (Cl, F) as acceptors the yeast-PDC-catalyzed addition proceeds with almost complete stereoselectivity to furnish the corresponding (R)-configurated 1-hydroxy-1-phenylpropanones 145 [447]. For practical reasons, whole yeast cells are most often used as the catalyst, with only small loss of enantioselectivity [423,424]. The conversion of benzaldehyde in particular has gained industrial importance because the acyloin is an important precursor for the synthesis of L-(-)-ephedrine [448]. Otherwise, the substrate tolerance is remarkably broad for aromatic aldehydes on the laboratory scale, however, yields of acyloins are usually low because of the prior or consequent reductive metabolism of aldehyde substrate and product, giving rise to considerable quantities of alcohol 146 and vicinol diols 147, respectively [423,424,449], The range of structural variability covers both higher a-oxo-acids (e.g. -butyrate, -valerate) as the donor component, as well as a,/J-un-saturated aldehydes (e.g. cinnamaldehyde 148) as the acceptor [450]. 

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