Cinnamaldehyde, cyclization with

Reaction of 2-isothiocyanato-/ra/w-cinnamaldehyde (110) with hydrazine gave the pyrazolo[l,5-c]quinazolines (111), presumably via the corresponding hydrazone and conjugate addition to the pyrazoline followed by cyclization [76JCS(P1)653]. 

Thermolysis of 12 with frans-cinnamaldehyde afforded the insertion compound 19, formed through the di-insertion of two carbonyl ligands into the C—Si bond of 12. The reaction of 12 with fumaronitrile yielded the cyclization product 20. X-ray study revealed 20 to be a cyclization product which contains two types of disilyl moieties, imino and N,N-bis(silyl)amino, which are connected by a five-membered ring. 

Jiang J, Yu J, Sun XX, Rao QQ, Gong LZ (2008) Organocatalytic asymmetric three-component cyclization of cinnamaldehydes and primary amines with 1,3-dicarbonyl compounds straightforward access to enantiomerically enriched dihydropyridines. Angew Chem Int Ed 47 2458-2462... 

An example of an intriguing ring-size dependency of the reaction pathway is that of the cyclization of vinylogous urethanes 328a-c with cinnamaldehyde (08T883). Pyrrolidine- and azepane-based esters 328a and c, respectively, give via aza-[3+3] annulation the expected... 

The yields of pyridines are generally low, but precursors for equation (10) are easily prepared by condensation of cinnamaldehydes with acetophenones. Sulfonyl- and acyl-hydrazones of o-ethynylbenzaldehyde can be cyclized by base to give isoquinolinium ylides (equation 12) (80JCS(P1)1331>. 

The ortho-substituted isothiocyanates are valuable intermediates for the preparation of a variety of heterocyclic compounds for example, o-isp-thiocyanato-( )-cinnamaldehyde with sodio diethyl malonate undergoes facile cyclization to 3-formylquinoline-2(l//)-thione,9 which in turn may be used for the preparation of tricyclic9,10 and large ring heterocyclic compounds."... 

Hydrolysis of 2-alkoxy-3,4-dihydro-l,2-pytans with dilute hydrochloric acid furnishes a convenient synthesis of glutaraldehyde (R = H) and other l,5 dicarbonyl compounds. The starting materials are obtained by the 1,4-addition of vinyl ethers to a,/3-unsaturated carbonyl compounds. The wide selection of diene systems includes acrolein, crotonaldehyde, meth-acrolein, cinnamaldehyde, /3-furylacrolein, methyl vinyl ketone, benzal-acetone, and benzalacetophenone. Ethyl vinyl ether is preferred as the dienophile. The yields in the cyclization step are in the range of 25 87% and in the subsequent hydrolysis Step, 55 85%. ... 

Styrenes react with the Vilsmeier reagent to give cinnamaldehydes, often in excellent yields. In some cases, when the benzene ring is electron rich, the product at higher temperatures may be an indene, such as compound 11, formed by cyclization of the intermediate cation (Eq. 7). Polymerization of styrenes (and... 

As presented in some detail by Gingrich and Baum (see their Table 4.31 and Scheme 4.51) azlactones react with ot,p-unsaturated imines to give ot-pyridones. Sandhu and co-workers continued the studies in this area, and they now view this reaction as involving initial electrophilic attack on the azlactone (munchnone) followed by cyclization to an ot-pyridone, rather than prior ring-opening to the corresponding ketene tautomer, as was originally proposed (Table 4.1). With azlactone 52 and A-aryl cinnamaldehyde anils 53, in the presence of acetic anhydride, the 4-substituted azlactones 54 are isolated (Fig. 4.15). Dalla Croce... 

SCHEME 2.25 Cyclization reaction of cinnamaldehydes 75 and aniUnes 51 with 1,3-dicarbonyl compounds 91. 

Scheme 14.3 shows the effect of the organocatalyst in the asymmetric Michael addition of malonic derivative 16 on cinnamaldehyde 15. After cyclization, water is expelled to form the A/-acyliminium intermediate 20 that is prone to Mannich-type addition of the indole. This addition generates the spirocyclic secoyohimbane scaffold and the unstable imidoyl bromide 21 that is hydrolyzed by the previously liberated water. This terminates the cascade and provides the spiroindolone with four stereo-centers. 

Jiang et al. proved that phosphoric acid can efficiently activate 1-aza-1,3-butadienes for the cycloaddition reaction (Scheme 2.26). In the presence of 10mol% H8-BlNOL-based phosphoric acid 6f, cinnamaldehydes 87, primary amines 7, and 1,3-dicarbonyls 88 nnderwent three-component cyclization reactions smoothly to give enantioenriched 4-aryl snbstituted 1,4-dihydropyridines 89 with high enantioselectivities of up to 98% ee [37]. 

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